Planning and Management of Lakes and Reservoirs

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PLANNING AND MANAGEMENT OF LAKES AND

RESERVOIRS:

AN INTEGRATED APPROACH TO

EUTROPHICATION

A TRAINING MODULE

UNEP-IETC

UNEP International Environmental Technology CentreOsaka/Shiga, 2000


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Disclaimer

The designation of geographical entities in this publication, and the presentation ofmaterial, do not imply the expression of any opinion whatsoever on the part of the UnitedNations or the United Nations Environment Programme concerning the legal status of

any country, territory, or its authorities, or concerning the delimitation of its frontiers orboundaries.

The views expressed in this publication do not necessarily reflect those of the UnitedNations Environment Programme.

The opinions, inputs as well as the recommendations provided by the governmentrepresentatives participating in the Training Workshop did not state the official positionof their countries, but their personal reflections as experts in their own capacity and as

civil servants.

Cover Photograph

Barra Bomita Resrvoir, Brazil (Jose G. Tundisi)Sulejow Reservoir, Poland (Malgorzta Tarczynska)

IETC Technical Publication Series Issue 12

ISBN 92-807-1810-X


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FOREWARD

One of United Nations Environment Programme-International EnvironmentalTechnology Centre (IETC) mandates is related to the development, facilitation andtransfer of Environmentally Sound Technologies (ESTs) for the conservation and

environmental management of freshwater resources. Under the project Planning andManagement of Lakes and Reservoirs (PAMOLAR) the book entitled Planning andManagement of Lakes and Reservoirs, An Integrated Approach to Eutrophication wasproduced (IETC Technical Publication Series number 11) in 1999. This book provided ageneral overview about the problems and possible solutions of eutrophication infreshwater lakes and reservoirs.

Knowledge needs to be transferred and information facilitated, hence capacity buildingbecomes crucial in this process; based on this need, the present Training Module has beenproduced. The Module deals with the problems of eutrophication of lakes and reservoirsby considering its origins, consequences, solutions, and prognoses under an integrated

approach. The training objective is to assist local authorities in their effort to prevent,reduce, and control the eutrophication of lakes and reservoirs through the application ofsound management practices. This publication outlines a new approach to waterresources management, particularly eutrophication, emphasizing the need to integrate andsolve simultaneously social, cultural, economic, and other associated problemsconsidering, at the same time, the natural setting of the lake or reservoir and itsenvironment. The watershed approach, which should be adopted in successfulmanagement strategies for water quality in lakes and reservoirs, is highlighted.

In January 2000, A Pilot Training Workshop took place in Naivasha, Kenya, using a draftversion of the Training Module. At the time some of the experts involved in thepreparation of the book as well as in the draft Training Module acted as lecturers in theirrespective areas of knowledge to ensure the best possible transfer and facilitation ofknowledge. In total twelve participants including Government experts and sub-regionalgovernment representative from African countries participated in the Training Workshopand an expert from the University of Lodz in Poland participated as an Observer. Theircomments, opinions and recommendations as experts were crucial in the finalization ofthe present Training Module.

IETC sincerely hopes that local decision maker, government official or otherprofessionals engaged in the planning and management of freshwater resources findsthese publications to be useful and that they, in turn, could be used for training activitieson eutrophication at a national, sub-regional or regional level.

Steve HallsDirectorUNEP-DTIE-IETC


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ACKNOWLEDGEMENTS

This training module is derived from and complements the book, PLANNING ANDMANAGEMENT OF LAKES AND RESERVOIRS, AN INTEGRATED APPROACH

TO EUTROPHICATION, published under IETC Technical Publication Series No.11

(1999) and also available on the IETC Web site (http://www.unep.or.jp)

Experts contributing to the preparation of the training module are as follows:

John M. Melack (Editor),Donald Bren School of Environmental Science and Management,University of California, Santa Barbara, CA, USA

Francisco Brzovic, University of Chile, Santiago, Chile

Genady Golubev, Moscow State University, Moscow, Russia

Sven Jorgensen, Royal Danish School of Pharmacy, Denmark

Charles Kolstad, University of California, Santa Barbara, CA, USA

Christopher H.D. Magadza, University of Zimbabwe, Harare, Zimbabwe

Monique Trudel, Educom Environnement, Montreal, Quebec, Canada

Jose G. Tundisi, University of Sao Paulo at Sao Carlos, Sao Carlos, Brazil

Participants in the Pilot Training Workshop held at Naivasha, Kenya, in January 2000were as follows: Ahmed S.A. Hussein (Sudan), Jobo Molapo (Lesotho), Musa Kilonzo(Kenya), Ibraheem A. Olomoda (Niger), Peter Chola (Zambia), Fikremariam Kahsai(Eritrea), Alex M. Banda (Malawi), Vusumuzi Simelane (Swaziland), Judith Mwabeza(Tanzania), Lillian Idrakua (Uganda), Amie Jarra (Gambia), Malgonata Tarczynska(Poland), Vicente Santiago (UNEP-IETC), Yinka Adebayo (UNEP, Regional Office forAfrica), Samuel M. Gitahi and Sarah Higgins (Lake Naivasha Riparian Asssociation),Christopher M. Warui (Lake Naivasha Growers Group), Mbogo Kamau (Kenya Marineand Freshwater Research Institute), Anderson Koyo (Kenya Wildlife Service), IgnatiusAbiya and P.N. Chege (Kenya Wildlife Service Training Institute), Kitaka Nzula(Egerton University, Kenya), and Kenneth M. Mavuti, Otieno N. Amos, Murage D.Lionel, Judith Nyunja, Msafiri Wambua, G.M. Kivengea, Dorothy Nyingi, WairimuMuohi and Chihenyo Muoyi (University of Nairobi).

The project was fully financed by UNEP-IETC complemented by a contribution in kindfrom the University of California, Santa Barbara. The Kenya Wildlife Service TrainingInstitute hosted the activity and the Regional Office for Africa of UNEP assisted inorganization of the workshop.


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TABLE OF CONTENTS

INTRODUCTION 1

1. ENVIRONMENTAL ASPECTS OF EUTROPHICATION

Introduction 2Limnological Background 2Characteristics of Eutrophication 4Effects of Eutrophication 4Assessment Approaches 6Modeling Approaches 7Study Questions 7

2. TECHNOLOGICAL ASPECTS OF EUTROPHICATION CONTROL

Introduction 9Sources of Pollutants 9Wastewater Treatment Systems 9Selection of a Proper Solution to Defined Wastewater Problems 14Ecological Approaches to Sanitation 15Waste Disposal Problems 17Control of Land Use 18Lake Restoration Methods 18Sediment Control 19Monitoring as a Management and Decision-Making Tool in Water Quality 19Decision-Making for Eutrophication Management and Control 20Study Questions 20

3. ECONOMIC ASPECTS OF EUTROPHICATION

Introduction 21The Economics of Eutrophication 21Using Regulations and Incentives to Reduce Eutrophication 22Choosing Regulations: Benefit-Cost Analysis 26Measuring Costs and Benefits of Reducing Eutrophication 29Study Questions 33

4. PUBLIC AWARENESS AND ENVIRONMENTAL EDUCATION

Introduction 34Environmental Public Awareness 35Tools of Public Awareness Development 35Information Sources and Dissemination 36


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Characteristics of the Most Effective Tools 36Public Participation 36Environmental Education 39Funding 40Study Questions 41

5. CULTURAL AND SOCIAL ASPECTS OF EUTOPHICATION

Introduction 42Societies and their Social and Cultural Aspects of Water 42Study Questions 45

6. POLICY, LEGAL AND INSTITUTIONAL FRAMEWORK

Introduction 46Background 46

Strategies for Eutrophication Control 47Institutional Framework 49Regulatory Framework 50Resources 51Study Questions 52

7. MANAGEMENT ISSUES

Introduction 53Basic Components of a Management Structure 53Lake Chivero, Zimbabwe 55Lessons Learned from Lake Chivero 59Management Experiences in Eastern and Central Europe 59Management Concerns related to Climate Change 61Study Questions 62


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INTRODUCTION

This training module deals with the eutrophication of lakes and reservoirs by consideringits origins, consequences, solutions, and prognoses under an integrated approach. The

objective is to assist local authorities in their effort to prevent, reduce, and control theeutrophication of lakes and reservoirs through the application of sound managementpractices. This publication outlines a new approach to water resources management,emphasizing the need to integrate and solve simultaneously the social, cultural,economic, environmental and other problems associated with eutrophication. Thewatershed approach is highlighted as a strategy to be adopted in the successfulmanagement of water quality in lakes and reservoirs.

Eutrophication of lakes and reservoirs originates from inputs of nutrients, such asnitrogen and phosphorus. Accelerated eutrophication of lakes and reservoirs,experienced in most parts of the world and largely caused by agricultural run-off and

untreated industrial and urban discharges, represents a serious degradation of waterquality. Impairment of water quality due to eutrophication can lead to health-relatedproblems and result in economic losses.

The provision of access to clean and safe water is one of the major challenges ofsustainable development. However, by 2025, the majority of the worlds population willlive in water stressed areas. By 2025, there will be 33 megacities with populations above8 million people and 500 cities with populations above 1 million people. The worldspopulation is growing at a rate of 100 million annually. Therefore, eutrophication is achronic environmental problem that will not abate because there is no zero dischargeoption for humans, and organic and nutrient-rich wastes will continue to be added tolakes, rivers and reservoirs

The prevention of eutrophication and the restoration of eutrophic lakes and reservoirsrequire proper planning and management of associated watersheds. Generally, human-caused eutrophication can be reversed through the elimination or reduction of nutrientsupplies from sources such as municipal and industrial wastewater, agricultural wastesand fertilizers. However, it is not possible to eliminate all sources of nutrients. Therefore,sound management strategies require an understanding of the relationship betweennutrient sources and degree of the eutrophication.

The watershed, a physical unit with a hydrologically integrated ecosystem, has beenadopted as a unit for integrating research and monitoring and for managing andadministering water resources. Integrated management should be adaptive, producingnew ideas and tools, and can only be achieved with local participation and political andmanagerial support. Education at all levels plays a fundamental role. Without theallocation of resources for educating and training scientists and engineers who managewater resources, there is no hope of finding solutions.


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Chapter 1 ENVIRONMENTAL ASPECTS OF EUTROPHICATION

Introduction

Eutrophication of inland waters ranks as one of the most widespread environmentalproblems. Symptoms of eutrophication include algal scums and toxins derived fromalgal blooms, massive infestations of certain aquatic plants, increased incidence of water-related diseases, turbid water, noxious odors and poor tasting water, depletion ofdissolved oxygen, and fish kills.

Eutrophication of lakes and reservoirs is the result of processes associated withenrichment with plant nutrients, mainly phosphorus and nitrogen. These nutrients enterlakes and reservoirs both as dissolved solutes and as compounds bound to organic andinorganic particles. Augmented nutrient inputs to inland waters usually result frommodifications of watersheds, such as deforestation, agricultural and industrial

development and urbanization.

The scientific basis for evaluating the causes and impacts of eutrophication is derivedprimarily from limnology, the study of the physical, chemical, and biological processes ininland aquatic environments. Limnology has a long and successful tradition of applyingscientific knowledge to the management of inland waters. Therefore, training inlimnology should be an integral part of the education of those responsible for themanagement of lakes or reservoirs.

Limnological Background

Physical processes determine the extent of stratification and mixing in lakes, which, inturn, determine ecosystem structure and function, and ecosystem responses toenrichment. Based on vertical density profiles, limnologists divide lakes and reservoirsinto an epilimnion (upper mixing layer), a metalimnion (region with a strong gradient indensity), and a hypolimnion (region below the metalimnion).

Flushing rate can have a significant influence on the responses of a lake to enrichment.Reservoirs and floodplain lakes can experience especially strong riverine flushing, atleast in certain seasons. Shallow lakes with inflows and outflows can flush rapidly.Conversely, lakes which exchange water via seepage or those with large volumes, havemuch longer residence times. While inflows often supply nutrients that enhanceeutrophication, rapid flushing can reduce the time available for plant growth and result inless accumulation of biomass.

Biotic communities in lakes can be divided into those in the open water (pelagic region),those in deep-water sediments (profundal zone), and those in near-shore habitats (littoralzone). Responses to eutrophication vary among these areas, and physical processes andmovements of organisms link the three regions. Pelagic organisms includephytoplankton, zooplankton, free-living and particle-attached bacteria, and fish. The


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biota inhabiting the profundal sediments includes a wide variety of invertebrates andmicrobes, and their abundance and species composition is influenced strongly by theextent to which the sediments are oxygenated or anoxic (oxygen-free). Emergent,submerged and floating vascular plants often are conspicuous in the littoral zone. Theseplants provide habitat for attached animals, algae and bacteria, and for free swimming

fish and invertebrates.

Limiting Factors

Light and nutrients determine the growth of algae and aquatic vascular plants. Therefore,if these resources are in short supply, they can be considered limiting factors for plantgrowth. Although one factor seldom consistently limits plant growth under the varyingconditions prevalent in aquatic ecosystems, dominant control, at a particular time andplace, often can be attributed to a single factor.

Light availability plays a key role in the development of submerged aquatic vascular

plants, which are usually rooted and can access sediments for nutrients. Hence, watersmade turbid by suspended sediments or algal blooms, or shaded by floating aquatic plantsare not conducive to the growth of submerged, aquatic vascular plants. In contrast,floating plants are well positioned to receive sunlight, and derive inorganic nitrogen andphosphorus from the water.

Phytoplankton abundance and species composition change as a function of the supplyrate of nutrients and underwater light conditions. Some species of cyanobacteria, an algalgroup known to produce noxious conditions, can regulate their buoyancy and oftenbecome common as turbidity increases.

External Loading to Lakes

Rivers and streams are major routes of transfer of nitrogen and phosphorus to many lakesand reservoirs, and they integrate the various point and non-point sources of nitrogen andphosphorus within their watersheds. The mining of phosphate, the industrial fixation ofnitrogen, and agricultural, industrial and domestic uses of nitrogen and phosphorus haveincreased during the last few decades. Other activities of modern societies, such as forestclearing, extensive cultivation and urban waste disposal, have enhanced the transport ofnitrogen and phosphorus from terrestrial to aquatic environments. While point and non-point sources of nitrogen and phosphorus contribute to eutrophication, non-point sourcesoften are dominant and present complex management challenges.

Atmospheric deposition via rain, snow and aerosols is an increasingly important externalsource of nutrients to lakes and reservoirs. Major sources of nitrogen to the atmosphereinclude burning of fossil fuels and forests, operation of internal combustion engines, andvolatilization from feed lots and fertilized fields. Augmented phosphorus deposition canoriginate from phosphorus-rich soil particles on fertilized and cultivated agriculturalfields.


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Internal Recycling

Internal recycling of nitrogen and phosphorus from sediments of lakes and reservoirs cansustain eutrophic conditions for long periods even if external loading is reduced.Empirical studies and models that incorporate biogeochemical and physical processes are

usually employed to evaluate the likelihood that internal recycling will compensate forlowered external inputs. Shallow, warm water lakes with a history of receiving nutrient-rich inflows are especially likely to maintain high rates of internal recycling.

Organic matter settles to the bottom and decomposes by aerobic or anaerobic processes.Decomposing organic matter reduces oxygen concentrations and can lead to or maintainanoxic conditions. Nitrogen and phosphorus release from the sediments to the overlyingwater is often increased under anoxic conditions.

Characteristics of Eutrophication

Lakes and reservoirs can be broadly classed as ultra-oligotrophic, oligotrophic,mesotrophic, eutrophic or hypereutrophic depending on concentration of nutrients in thebody of water and/or based on ecological manifestations of the nutrient loading. Theseso-called trophic categories are often based on total phosphorus concentrations,chlorophyll concentrations and Secchi disk visibility. Strict boundaries for thesegroupings are often difficult to define because of regional variations in limnologicalparameters (See Figure 1.3 in IETCs Technical Information Series number 11).

In general terms, oligotrophic lakes and reservoirs are characterized by low nutrientinputs and primary productivity, high transparency and a diverse biota. In contrast,eutrophic waters have high nutrient inputs and primary productivity, low transparency,and a high biomass of fewer species with a greater proportion of cyanobacteria than inoligotrophic waters.

Effects of Eutrophication

Algal Blooms

A pervasive result of enrichment of lakes with nutrients is increased growth of algae.Cyanobacteria are an especially troublesome group that are known to form unsightlysurface scums, to cause severe oxygen depletion and fish mortalities, and to lead to deathof cattle and other animals from ingestion of algal toxins. Filamentous species ofcyanobacteria or green algae (chlorophytes) can clog filters in water treatment orindustrial facilities. Dinoflagellates are another group of phytoplankton that can causetoxic conditions. One by-product of algal blooms can be high concentrations of dissolvedorganic carbon (DOC). When water with high DOC is disinfected by chlorination,potentially carcenogenic and mutagenic trihalomethanes are formed.


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Growth of Aquatic Plants

Dense mats of floating aquatic plants, such as water hyacinth (Eichhornia crassipes), anaquatic fern (Salvinia molesta) and Nile cabbage (Pistia stratiotes ), can cover large areasnear-shore and can float into open water. These mats block light from reaching

submerged vascular plants and phytoplankton, and often produce large quantities oforganic detritus that can lead to anoxia and emission of gases, such as methane andhydrogen sulfide. The material derived from these plants is usually of low nutritionalquality and is not often an important component of the food for zooplankton or fish.Accumulations of aquatic macrophytes can restrict access for fishing or recreational usesof lakes and reservoirs and can block irrigation and navigation channels and intakes ofhydroelectric power plants.

Anoxia

A by-product of increases in the abundance of algae and aquatic macrophytes is

generation of more organic matter. As this organic matter decomposes in the watercolumn or in the sediments, the concentration of dissolved oxygen decreases. In shallowlakes and where plant production is large, complete deoxygenation of the sediments andwater can occur. Such conditions are not compatible with the survival of fishes andinvertebrates. Moreover, under anoxic conditions, ammonia, iron, manganese andhydrogen sulfide concentrations can rise to levels deleterious to the biota and tohydroelectric power facilities. In addition, phosphate and ammonium may be releasedinto the water from anoxic sediments, further enriching the lake.

Species Changes

Shifts in the abundance and species composition of aquatic organisms often occur inassociation with alterations of ecosystems caused by eutrophication. Reduction inunderwater light levels because of dense algal blooms or floating macrophytes can reduceor eliminate submerged macrophytes. Changes in food quality associated with shifts inalgal or aquatic macrophyte composition, and decreases in oxygen concentration oftenalter the species composition of fishes.

Elevated Nitrate Concentrations

High concentrations of nitrate resulting from nitrate-rich runoff or nitrification ofammonium within a lake can cause public health problems. The inhibition of the abilityof infants to incorporate oxygen into their blood can result in a condition called blue babysyndrome (methylhaemoglobinaemia) if nitrate levels are above 10 mg per liter indrinking water. The condition can be life-threatening.

Increased Incidence of Water-related Diseases

In some situations eutrophication stems from untreated human sewage reaching lakes andreservoirs. If a portion of the population producing the sewage suffers from infections


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transmitted directly or indirectly via water, the spread of human diseases occurs. Whilesuch situations are especially prevalent in tropical countries where poverty is commonand the number of diseases is large, avoiding the spread of disease via water is a concernfor all countries. Indeed, municipal water supplies that pipe water throughout a city fromcentral storage reservoirs are highly susceptible to spread of diseases, such as typhoid or

cholera, that can be seeded by seemingly negligible fecal pollution from infected persons.

Increased Fish Yields

Yields of fish tend to increase as primary productivity increases in lakes, reservoirs andin aquacultural systems. Assuming that the fish whose yields are improved are edible andmarketable, the increase in primary productivity often associated with nutrientenrichment can have a positive result up to a point (see Figure 1.7 in IETCs TechnicalInformation Series number 11).

Assessment Approaches

The ambient concentrations of nutrients sometimes can provide an indication of the levelof eutrophication. Often the limiting nutrient is reduced to very low concentrations, whilenutrients less in demand have higher concentrations. However, nutrients are present indifferent forms, which vary in their relevance to assessing eutrophication. In most studiesof rivers and standing waters, the forms of phosphorus and nitrogen are operationallydefined based on available analytical methods. The distinction between particulate anddissolved forms depends on the porosity of the filter used to separate the two fractions;filters with porosities approximately 0.5 m are commonly used. Total dissolvedphosphorus is often divided into soluble reactive phosphorus, which can sometimes beconsidered dissolved inorganic phosphorus, and dissolved organic phosphorus. Similarly,total dissolved nitrogen includes dissolved inorganic ammonium, nitrate, and sometimesnitrite and urea, and dissolved organic nitrogen. Total particulate phosphorus andnitrogen are determined as particulate inorganic phosphorus and nitrogen and particulateorganic phosphorus and nitrogen. In some cases, concentrations of total phosphorus ornitrogen are measured; these include all the dissolved and particulate forms. However,only a portion of the total phosphorus or nitrogen is biologically available.

The nitrogen to phosphorus ratio in particulate organic matter suspended in lakes is apotentially valuable index of the nutritional status of the phytoplankton. Healthy algaecontain approximately 16 atoms of nitrogen for every atom of phosphorus. Ratios ofnitrogen to phosphorus less than 10 often indicate nitrogen deficiency and ratios greaterthan 20 can indicate phosphorus deficiency. Often nitrogen to phosphorus ratios are lowin eutrophic lakes and high in mesotrophic and oligotrophic ones, and blooms ofnitrogen-fixing cyanobacteria have been induced experimentally in lakes after reducingnitrogen to phosphorus ratios in inflows.

The rate of uptake of radioactive phosphate by particulate matter suspended in lakes is awidely used index of phosphorus demand by the plankton. Turnover times are typicallyrapid when phosphorus is in short supply and are slow when supply is adequate.


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Nutrient limitation can be assessed by experimental manipulation of nutrient levels.Experiments can be carried out on scales ranging from small flasks to enclosurescontaining many liters to whole lakes. Large volume experiments provide more realisticconditions than small containers. Enclosures with volumes ranging from tens to

thousands of liters can be replicated with experimental designs that permit discriminationof interacting factors leading to changes in water quality.

Phytoplankton species composition changes in response to eutrophication. Althoughgeneral trends in the development of certain assemblages of phytoplankton are associatedwith trophic status, particular phyla or classes cannot be assigned exclusively to one levelof eutrophication. While cyanobacteria are commonly observed under eutrophicconditions, other species can be important.

Modeling Approaches

A model is a graphical, statistical or mathematical approximation of a real lake orreservoir. Models used for understanding eutrophication focus on nutrient loading fromthe watershed and on processes within the lake or reservoir. While these models haveconsiderable differences in their complexity, in most situations, simpler approaches aresufficient and are often the only practical option.

Simple empirical regression models have been developed to predict the concentration oftotal phosphorus in a lake or reservoir as a function of annual phosphorus loading.Extensions of such models offer predictions of chlorophyll concentrations inphytoplankton, Secchi disk visibility or dissolved oxygen levels.

Dynamic simulation models incorporate mathematical descriptions of physical, chemicaland biological processes in lakes and reservoirs. If properly designed and validated,these models can assist with management decisions. However, the data requirements andprocess-level understanding demanded by dynamic models can be formidable.

Evaluation of a model requires careful examination of the assumptions underlying themodel and a rigorous analysis of the way the model responds to a range of inputs. It isprudent to be skeptical of their predictive power and realism.

Study Questions

1. What measurements should be made to assess the level of eutrophication in a lake orreservoir?

2. Since the eutrophication control employed will depend, partially, on the levels ofnitrogen or phosphorus, how can their relative importance be assessed?


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3. What precautions should be taken before using a model to guide a managementdecision?

4. What type of training is essential for a water quality decision-maker?

5. What are the implications of eutrophication for lakes and reservoirs?

6. Why is it important to understand the process of eutrophication?


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Chapter 2 TECHNOLOGICAL ASPECTS OF EUTROPHICATION CONTROL

Introduction

This chapter focuses on possible solutions to the eutrophication problems presented in

Chapter 1. The solutions include methods to remove nutrients from wastewater and fromnon-point sources, techniques to reduce emissions at the source and methods to improveeutrophic lakes and reservoirs. Technological and cost-moderate approaches, which aredirectly applicable to developing countries, are emphasized. Guidelines, incorporatingdecision-making trees, are offered on how to select a solution to a specific environmentalproblem.

Important recommendations are as follows:

Expect that a successful strategy will require several approaches.

Expect that effective management will require the application of a combination oftechnologies.

Set up an environmental management plan at an early stage. Consider prevention instead of correction, as ecosystem restoration is often costly.

Proper ecological knowledge of the ecosystem is a prerequisite for soundenvironmental management.

An optimum solution can only be found if the entire watershed is considered.

Sources of Pollutants

The first step in lake and reservoir management of eutrophication is to assess the inputsof nutrients and their effects. A model of eutrophication may be helpful (for furtherdiscussion about modeling see Chapter 1). The measurement and modeling of sources

can be used to help assess the priority with which to reduce the sources.

Ecologically sound planning considers environmental issues at an early stage of planningand thus prevent pollution problems before they actually emerge. Wastewater problemscan be solved by end-of-the-pipe technology or ecotechnology. Ecotechnologyencompasses (a) ecologically sound planning, (b) use of natural or constructedecosystems to reduce inputs, and (c) restoration of ecosystems. Natural or constructedwetlands are being used to treat wastewater and drainage water from non-point sourcesincluding agriculture. Restoration methods can improve lakes and reservoirs faster thanotherwise would be the case, but they cannot be used alone. If the inputs are not reducedsimultaneously, the restoration methods will have only short-term effects.

Wastewater Treatment Systems

As wastewater treatment is often costly (Table 1), the maximum allowable concentrationsshould not be set significantly lower than those that the ecosystem can tolerate withoutadverse impacts. The costs in Table 1 are valid for treatment of 2000 m3 per day, i.e.,municipal wastewater for about 10,000 inhabitants. Costs per 100 m3 for smaller andlarger communities will vary somewhat.


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Table 1. Generally applied wastewater treatment methods for reduction in organic matterand nutrients. BOD5 means biological oxygen demand over 5 days.______________________________________________________________________Method Goal Efficiency % Costs (year 2000)

with good practice ($/100m3)

______________________________________________________________________Mechanical BOD5 reduction 20-35 3-8treatment

Biological treatment BOD5 reduction 70-90 25-40

Flocculation Phosphorus removal 30-60 6-9BOD5 reduction 40-60

Chemical Phosphorus removal 65-95 10-18precipitation BOD5 reduction 50-65

Al2(SO4)3 or FeCl3

Chemical Phosphorus removal 85-95 12-18precipitation BOD5 reduction 50-70Ca(OH)2

Ammonia stripping Ammonia removal 70-95 25-40

Nitrification Ammonium nitrate 80-95 20-30

Denitrification Nitrogen removal 70-90 15-25

Ion exchange Phosphorus removal 80-95 70-100Nitrogen removal 80-95 45-60

Waste stabilization Reduction of BOD5 70-90 2-8ponds Nitrogen removal 50-70

Constructed Reduction of BOD5 20-50* 5-15wetland Nitrogen removal 70-90

Phosphorus removal 0-80**

Activated carbon Reduction of organic 40-95 60-90adsorption toxic compounds, BOD5_____________________________________________________________________* Presumes a pretreatment (BOD5< about 75 mg/l)** The removal is dependent on the adsorption capacity of the soil applied and whetherharvest of the plants is foreseen.


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Waste Stabilization Ponds (WSPs)

Traditionally, waste stabilization ponds are built as flow-through systems with thefollowing processes being utilized in the pond system: settling (mainly in the first ponds),anaerobic decomposition of organic matter (mainly in the first ponds), aerobic

decomposition of organic matter (mainly in the last ponds, where algae are present andproduce oxygen), uptake of phosphorus and nitrogen by algae (maturation ponds),evaporation of ammonia (mainly where pH is high, i.e., in the last ponds), settling ofalgae, and denitrification (in the anaerobic zones). High removal efficiencies ofbiological oxygen demand over five days (BOD5), of chemical oxygen demand (COD),of microorganisms, of nitrogen, and of phosphorus may be obtained provided that theguidelines for design and maintenance are followed.

Removal of phosphorus by WSPs can be in the range of 20 to 50% but depends onremoval of algae from the effluent. Enhanced removal of phosphorus, which is oftenrequired for the discharge of wastewater to lakes and reservoirs, can be achieved by

addition of precipitants such as calcium compounds and clay minerals, which often havelocal sources.

Constructed Wetlands

The transition zones between lakes and terrestrial ecosystems are crucial for protection oflakes against anthropogenic impacts. Transition zones prevent, to a certain extent, entryof undesirable substances into lakes, and, therefore, should be preserved. Hence,construction should not be permitted in a zone 50 to 100 m from shorelines.

Non-point or diffuse pollutants from the environment flows toward lakes, but thetransition zone is able to transform or adsorb the pollutants. The most importantprocesses occurring in the transition zone are as follows:

Nitrate is denitrified by the anaerobic conditions.

Clay minerals adsorb ammonium.

Organic matter adsorbs phosphorus compounds

Biodegradable organic matter is decomposed aerobically or anaerobically bymicroorganisms.

Macrophytes store nutrients.

Soils with a high calcium, magnesium, aluminum or iron content can adsorbphosphorus.

Suspended matter is removed along with associated nitrogen and phosphorus.

The denitrification potential of wetlands is often high. As much as 2,000 to 3,000 kg ofnitrogen in nitrate can be denitrified per hectare of wetlands per year. In addition,denitrification is accompanied by oxidation of organic matter. However, phosphorus,bound in organic matter or adsorbed to the organic matter, may be released.

The siting of artificial wetlands must be carefully planned because their effects aredependent on the hydrology and on the landscape pattern. Non-fertile land of moderate


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cost should be used. Constructed wetlands can be either surface or subsurface wetlands.Subsurface wetlands are based on flow of water through the soil, and oxygen is providedfor biological decomposition via the root network. Subsurface wetlands are usually ofhigher efficiency than surface wetlands but require more maintenance to avoid clogging.When wetlands with open water are used, mosquitoes should be controlled, for instance,

by stocking of insectivorous fish. Harvest of wetland plants will increase the efficiency ofnitrogen and phosphorus removal. The harvested plants can be used to feed domesticanimals, to produce methane or be composted.

The combination of WSPs and constructed or reclaimed wetlands are attractive for thefollowing reasons:

Wetlands offer a significant reduction of suspended matter from WSP pond effluents.

Wetlands buffer the pH of the effluent from WSPs.

Effluents from WSPs often need a polishing step as a post treatment. Wetlands offer acost-moderate solution.

Mechanical-Biological Treatment Methods

Mechanical-biological treatment is widely used in industrialized countries and indeveloping countries where the cost of land is high (see the decision tree in Figure 1).Treatment costs of 28-48 U.S. $ / 100 m 3 are about 2-3 times the cost of treatment basedon the combination WSPs and constructed wetlands. However, where the cost of land ishigh and proper maintenance of the facilities is maintained, mechanical-biologicaltreatment could be preferable.

Mechanical treatment combines the use of a sieve, a grid chamber (with a retention timeabout 20 minutes during which sand settles and grease is removed) and a sedimentation

chamber where finer particles are removed during a retention of 2-6 hours. Biologicaltreatment follows mechanical treatment and uses air to accelerate the decomposition oforganic matter. Two alternative processes are an activated sludge treatment or a tricklingfilter. The trickling filter employs uptake of air from the atmosphere by recycling thewater over a large surface, while activated sludge uses input of air from an aerator orcompressor. A retention time of 2-6 hours is usually required to obtain 85-95% removalof BOD5. The biological step is followed by a secondary sedimentation where suspendedmatter resulting from the biological activity is removed. The sludge is partly recycled toensure a high concentration of active microorganisms in the biological step. The sludgecan be used to produce methane, and the stabilized sludge can be applied as soilconditioner, provided that it does not have too high a concentration of toxic substances

(for further details see chapter 6 in IETCs Technical Information Series number 11).

A mechanical-biological treatment plant can be modified and expanded to includeremoval of phosphorus and nitrogen. By addition of a precipitant in the grid chamber, itis possible to achieve a 75-95% removal of phosphorus during the primary sedimentation.Since phosphorus will be present in the stabilized sludge, it improves the quality of thesludge as a soil conditioner. Nitrogen removal by nitrification and denitrification ispossible by increasing the retention time considerably in the biological step and by


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switching between aerobic and anaerobic conditions. Nitrification requires an increasedrecycling of sludge, as the sludge age has to be increased to about ten days. Thesemodifications lead to an increase in treatment costs by a factor of 2-3 (see Table 1).

Scale ?

Large Medium Small

High cost of area Low cost of area Go to Figure 2.

High cost plant acceptable Low cost solution required

Mechanical-biological-chemical P-removal required;Treatment probably the best solution Partial BOD5removal needed

High BOD5 and P- Chemical precipitationremoval required (Recommended as a first treatment

step under all circumstances)

Chemical precipitation in combinationwith WSPs or wetland

Figure 1. Decision tree for the selection of wastewater treatment methods to be used formedium and large-scale facilities.


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Is the treatment of industrial wastewater with heavy metals

or organic toxic compounds needed?

Yes No

Treatment by use of High BOD5 Low BOD5 removal requiredWSPs, wetlands, removal requiredchemical precipitationand/or adsorption shouldbe considered

Area limited or Area available Correctly designedhigh cost of land at moderate cost WSPs sufficient

WSPs + aeration WSPs + wetland

P-removal needed?

Yes No

See Table 2. Nitrogen removal needed?

Yes: see Table 3. No

Figure 2. Decision tree for the selection of wastewater treatment methods

Selection of a Proper Solution to Defined Wastewater Problems

The selection of the best solution to the municipal wastewater problem requiresquantitative estimation of the relationship between the quality of the wastewater and thereceiving water. The pertinent question is how much phosphorus, nitrogen, and BOD5can be permitted in the treated wastewater to ensure acceptable water quality for thereceiving water body. Figure 1 and 2 present two decision trees that may facilitate theselection of a proper solution.


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Table 2. Treatment processes for the removal of phosphorus by cost-moderate methods_____________________________________________________________________

Method Expected efficiency______________________________________________________________________

Precipitation in WSPs 50-75%Harvest of wetlands (2-4 times/year) 40-180 kg P/haApplication of soil with high adsorp-tion capacity for phosphorus 100-300 kg P/haDirect precipitation in conjunction withmechanical-biological treatment 75-95%______________________________________________________________________

Table 3. Treatment processes for the removal of nitrogen by cost-moderate methods______________________________________________________________________

Method Expected efficiency______________________________________________________________________Denitrification in a constructed wetland 1,000-2,500 kg N/ha*Harvest of wetlands (2-4 times/year) 250-1,200 kg N/ha **Nitrification and denitrification 75-90%______________________________________________________________________* based mostly on experience from temperate climate (summer conditions).** based on the concentration of nitrogen in the common wetland plants; number ofharvests is dependent on climate

Ecological Approaches to Sanitation

Water-borne diseases are a common cause of illness and death in the developing world.Approximately 90% of the sewage in cities and 95% of the total amount of sewage indeveloping countries is discharged untreated. Hence, there is an urgent need for properoperation of conventional sewage treatment facilities and for new solutions to sanitation.

Flush-and-discharge systems make the problem of sanitation and wastewater worsebecause a relatively small amount of dangerous material (i.e., human feces) is allowed topollute a large amount of water. Yet, this approach is promoted in cities and townsaround the world, even in poor countries where people cannot afford it and in arid areaswhere there is insufficient water for drinking.

Ecological sanitation is an alternative appropriate in some circumstances. The approach isnot to mix the various components of wastewater: 1) human urine and feces (in thetoilet), 2) human excrement and water, 3) black water (from toilets) and grey water (fromkitchens and laundries), 4) household waste and industrial waste, and 5) waste andrainwater.


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Urine contains forms of nitrogen and phosphorus which are readily available to plants.Urine diluted by water can be used directly in gardens or in agriculture or it can be storedfor later use. If it cannot be used as a fertilizer, it may be infiltrated into the ground. Urineis separated from feces by use of a dry toilet with urine separation. Feces are preferablyprocessed in two steps before they are reused: dehydration locally in pits, followed by

high temperature composting to ensure destruction of pathogenic organisms. Thecompost product can be used as a fertilizer or soil conditioner.

Grey water from households has a much lower BOD5 and phosphorus and nitrogenconcentrations than mixed wastewater. It is therefore easier to treat grey wastewater bythe methods already presented. Otherpossibilities are use of wetlands directly or forinfiltration. Grey wastewater may be used after simple filtration (for example, by settling)for irrigation.

By not mixing storm water and wastewater, one can store, treat, and recycle storm waterlocally. However, maintaining separate streams requires two systems of drains and is

expensive. Industrial wastewater may contain toxic chemicals and must, in most cases, betreated at the source.

Wastewater

Municipal wastewater Industrial wastewater

Wastewater Stormwater Treatment at thesource

Black wastewater Grey wastewater Used for irrigationor treated in wetlands

Feces Urine Treated in WSPs and/or in wetlands

Composting followed by Used directly as fertilizer

use in agriculture

Figure 3. The principle of the not-to-mix approach: municipal and industrial wastewaterare not mixed. Storm water and wastewater are not mixed. Grey and the blackwastewater are notmixed and feces and urine are not mixed. Available methods (notnecessarily the best solution in all situations) for each fraction are indicated in italics.


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Waste Disposal Problems

Solid waste may be classified as follows:

Sewage sludge originating from mechanical-biological-chemical treatment, chemicaltreatment, or WSPs.

Solid wastes produced by urban and rural households from single family dwellings,villages and small-to-medium towns.

Non-treated solid waste can accumulate in large amounts. The non-treated waste becomesa non-point source of nutrients and other compounds, which contribute to eutrophicationand contamination of freshwater resources. Accumulation of solid waste may be reducedby recycling, by changing production methods, by decomposition to harmless compoundsor by disposal.

Solid waste Sludge

Contains toxic substances Contains toxic substances Contains toxic substancesabove the standards below the standards above the standards

Reuse and recycle as Reuse and recycle as Find sources and treatmuch as possible much as possible industrial wastewater

followed by composting accordingly

Find sources andeliminate them

Use landfills with membrane Use as a soil conditionernot possible beforestandards are met uselandfills with membrane

Figure 4. Decision tree for the selection of appropriate solutions to solid waste problemsof small to medium towns

The above discussion is summarized in a decision tree shown in Figure 4. Reusing andrecycling, in combination with composting, is a central solution, provided that theconcentrations of toxic substances can meet the standards. Anaerobic digestion of sludgeand air-drying may be used as a pretreatment of the sludge, but it is not included in thedecision tree. Incineration may replace composting, but for medium and small towns andvillages composting is more attractive. Proper control at the source of the problemsassociated with the presence of toxic substances is also a key to acceptable managementof the solid waste.


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Control of Land Use

Proper solutions of the wastewater and solid waste problems are a prerequisite, but arenot sufficient, to ensure a high water quality in aquatic ecosystems. The application of thesolutions mentioned above must be combined with a comprehensive land use plan.

The entire watershed influences water quality. Intensive agricultural or industrial use ofthe watershed will inevitably influence the quantity and quality of the water and theability of the ecosystem to cope with pollutants. Green areas are therefore not onlyimportant for recreation, but also for reduction of diffuse pollution which results fromintensive use. A mosaic of land uses should be represented in the landscape to ensurehealthy ecosystems and sustainability.

Lake Restoration Methods

A detailed overview of methods applicable to aid recovery of lakes is given in EITCsTechnical Publication Series number 11. A summary of restoration methods is given inTable 4, and a few important, relatively cost-moderate, methods are mentioned below.

Siphoning of hypolimnetic water requires installation of a suitable pipeline from thebottom of the lake to the outlet. The method is not recommended if there are downstreamlakes unless the water is treated. It is only applicable to lakes with a thermocline (orhalocline) for a significant period.

Harvest of macrophytes is recommended, particularly in cases where the macrophytescan be used to feed domestic animals or for production of methane. Herbicides should notbe applied as they contaminate water and biota.

Biomanipulation, i.e., removal of small fish feeding on zooplankton and stocking ofcarnivorous fish, is another cost-moderate method which is only effective in the totalphosphorus range of 0.05-0.15 mg/l. However, the potential hazards of introducedspecies must be carefully considered.

Sediment remediation can be carried out either by in situ methods or by removal of thesediment from the bottom of the lake or reservoir. In in situ remediation, air, or a mixtureof air and oxygen, is pumped and released at the sediment-water interface to eliminateanoxia in the bottom water. Capping sediments with clean material is one technique forsediments polluted with metals and organic compounds. Chemical treatment has beenused to immobilize phosphorus at the sediment-water interface. Additions of chemicals,such as ferric chloride and calcium nitrate, to the sediments can be used as chemicaltreatment. However, the treatment must be designed for a specific lake.


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Table 4. Methods for restoration of lakes and reservoirs.

Method Application Costs

In situ precipitation often not applicable to shallow lakes lowRemoval of sediment limited to shallow lakes very high

Algicides not recommended mediumCoverage of sediment general medium-highShading by trees has only long-term effects for small lakes very lowWetlands removal of nutrients from inflow water mediumAeration only applicable to lakes with thermocline high to very highSiphoning only applicable to lakes with thermocline medium, high if P-

removal is requiredBiomanipulation only in the P-range 0.05-0.15 mg/l usually lowDiversion the problem is moved not solved case dependent______________________________________________________________________

Sediment Control

The prevention of soil erosion in watersheds draining into lakes is an imperative step inthe control of non-point sources of nutrients and agricultural chemicals. Human-madechanges to river and stream banks, and changes in flow characteristics result in increasederosion of exposed riverbanks. Changes are caused by removal of tree cover and ofground cover for agricultural production. Cattle, sheep, and other animals with freeaccess to streams and rivers cause bank collapse and damage. To prevent this type oferosion, fences to exclude access of animals to the stream or river are required; access fordrinking must be provided by construction of an access point.

Monitoring as a Management and Decision-Making Tool in Water Quality andEutrophication

In most countries, including most developing countries, monitoring of water quality hasoccurred for many decades. In the past, and even today in some lesser developedcountries, monitoring has been mainly focused on public health issues with a principalinterest in microbiological vectors that are the main causes of water-borne diseases. Insuch cases, water quality monitoring is generally under the control of ministries of health,and the larger dimensions of aquatic pollution may not be included in such programs.However, as countries become more developed and the range of aquatic impacts fromwater pollution increase, monitoring becomes more comprehensive with the hope that it

will provide information on a wide range of water quality management issues.Unfortunately, in many countries, including many developed countries, it has been theexperience of many professionals that monitoring tends to be poorly focused and withoutclear sets of program objectives. The consequence is that these programs are inefficientand do not provide the level of information that is needed to provide an effective tool formanaging environmental concerns.


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Decision-Making for Eutrophication Management and Control

The scientific understanding of eutrophication, at least in temperate middle latitudes, issufficiently well known that the control of eutrophication is a matter of political will,necessary finance, and effective institutional organization. The principal technical

deficiencies, especially in developing countries, tend to be: (a) the absence of adequatewater quality standards (and enforcement of these) against which to assess the severity ofeutrophication, and (b) the absence of data with which to develop remedial options.

Monitoring programs should reflect the types of decisions that need to be made to carryout the following management tasks:

Identify relative contributions of different pollutant sources.

Allow calculation of nutrient input/output budgets into the receiving river, lake, orreservoir.

Predict change in ecological condition that would result from specific management

interventions. Assess alternative management interventions in terms of cost/benefit.

Study Questions

1. Explain why a proper environmental strategy requires a wide spectrum of approaches.

2. Explain why prevention is more cost moderate than solving the problems after theyhave emerged.

3. By which methods can ammonia be removed from wastewater?

4. Which advantages have WSPs and constructed wetlands as applicable technology fordeveloping countries?

5. Which components can be removed by WSPs and by constructed wetlands?

6. Give three major advantages associated with the use of ecological sanitation.

7. Give a solution to solid waste and sludge problems for a medium-sized town in whichboth sludge and waste contain toxic substances above the standards.

8. What is gray wastewater and black wastewater? Separate treatment of these two typesof wastewater offers what advantages?

9. Why should we consider the entire drainage area to develop a good environmentalstrategy?

10. What are some important functions of riparian wetlands.


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Chapter 3 ECONOMIC ASPECTS OF EUTROPHICATION

Introduction

The economic dimensions of eutrophication are considered in this chapter. As was

described in Chapter 1, eutrophication is viewed as a problem associated with domestic,agricultural and industrial activities: factories processing foodstuffs, fertilizer applicationin agriculture and municipal sewage discharge. Furthermore, eutrophication candetrimentally affect a range of activities that involve the direct or indirect use of water.Factories discharge effluent to save money, agriculture applies inorganic fertilizer toboost output and profits, waste from raising animal is costly to collect and treat, sewageis inadequately treated because of the cost of more complete treatment and, in manycases, the reluctance of customers to bear the extra cost. Water users incur higher costsor tolerate lower water quality as a result of eutrophication.

This chapter addresses two basic questions faced by regulatory authorities in designing

policies to reduce nutrient loadings. Since those generating pollutants are often doing sofor economic reasons, an important question concerns what economic incentives can beput in place to encourage a reduction in nutrient loadings. A second question concernshow a regulatory authority weighs all of the positive and negative economic effects ofreducing nutrient loadings in order to choose an appropriate set of interventions in theeconomy. The sectors producing pollution are often important to local economies;imposing extra costs may lead to job loss and other undesirable consequences. On theother hand, many sectors of the economy as well as residents will benefit from reductionsin eutrophication. Regulatory authorities will want to evaluate both the positive andnegative aspects of controlling eutrophication.

This chapter consists of three parts. In the first part we review the problem ofeutrophication through the lens of economics, introducing concepts and highlighting theeconomic reasons for eutrophication problems. In the second part we turn to theeconomic dimensions of regulatory approaches for controlling eutrophication. In thethird part we consider how the costs and benefits of controlling eutrophication can bemeasured and tallied.

The Economics of Eutrophication

As was explained in Chapter 1, nutrients leading to eutrophication are generated asbyproducts of industrial and agricultural activity as well as being contained in the

discharge of municipal waste. In all of these cases, nutrient generation is doneinadvertently or to save money. For example, agricultural processing generates largevolumes of waste which at a cost may be composted or treated; it is cheaper to simplydischarge the waste into a water body.

Nutrient discharges which lead to eutrophication degrade the quality of water bodiescausing harm to water users. Harm may be increased costs for water users, such ashydroelectric facilities or drinking water suppliers. Fishermen may suffer yield losses


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that translate into lost income. The well being of people may suffer from lost recreationopportunities or a loss of biodiversity.

The phenomenon whereby one agent (a farmer or a factory) discharges pollution toreduce its own costs but in the process increases costs for others is known as a negative

externality. For example, a coffee processing facility saving money by discharging itswastes into the lake is increasing the costs of those who use the lake. The coffee wastedischarge is an externality, increasing costs for water users. If the coffee processor tookthe effect of its discharges into account, it would most likely take steps to treat the wasteand there would be no problem. But in fact, those effects on others are external effectswhich are not considered when the coffee producer decides how to operate. Thus, it isnecessary for a regulatory body to correct the externality.

A distinction should be made between point and non-point sources of nutrients. Pointsources, defined as a stream of pollution coming from a pipe or other "point" are easier tocontrol because of the ease of monitoring and the ease with which the responsible party

can be identified. Non-point sources, such as agricultural fields, are more difficult to dealwith because of problems in identifying which of many possible sources is responsiblefor the pollution and also because of the difficulty in measuring discharges.

Using Regulations and Incentives to Reduce Eutrophication

A government can use various tools to reduce nutrient loadings to appropriate levels. It isnot sufficient to simply decide that nutrient inputs into a certain lake should be cut inhalf. It is necessary to develop techniques for translating this objective into actions thatspecific polluters undertake. An agency may rely on direct regulation of polluters orinstitute economic incentives, such as a tax reduction for investment in pollution control.We will use the term "instrument" to describe a specific approach an agency chooses tocontrol the polluter so that discharges are brought under control. For example, theagency may choose a tax instrument or a direct regulatory instrument. We discuss thesebelow.

Classification of Instruments.

There are three main categories of environmental management instruments:

Direct regulatory instruments:Direct regulatory instruments, also called"command and control" instruments, correspondto institutional measures oriented to influence directly the environmental behavior ofeconomic agents (polluters) in order to regulate production processes or productcharacteristics, and/or limit the discharges of certain pollutants to the environment, and/orrestrict activities in certain periods of time or areas. These actions require a previousdefinition of environmental standards incorporating government environmentalobjectives with reference to human health, natural resource conservation, ecologicalconsiderations and other issues. For instance, pollutant quantities that can be dischargedare specified, technologies that can be implemented by particular industries are


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prescribed, or criteria or quotas are authorized when exploiting natural resources. Directregulatory instruments include emission standards, permits and licenses, land use andwater control, and urban planning, among others.

An instrument that sets an upper limit on the nutrient level in water discharges from

coffee processing facilities would be an example of a direct regulatory instrument.

Persuasive instruments:Persuasive instruments consist of non-economic programs, activities and actions orientedto make agents internalize environmental responsibilities in their decision-makingprocesses. Information, education, training and volunteer agreements among governmentand entrepreneurs are valid examples of this group of instruments. The perception that acompany is a good company or a green company can provide an incentive for them toreduce emission levels. Governments may have a role in making consumers aware of thedeleterious effects of eutrophication and encourage consumers to place pressure on thosefrom whom they buy their goods. This type of incentive process corresponds to the

persuasive group of instruments; however, is difficult to manage and will usually onlyoccur over the long run. It is not suitable where the problem is immediate. There mayalso be opportunities for direct bilateral negotiation between the government and thepolluter, in order to reach agreement on steps to control emissions.

Economic instruments:Economic instruments are a specific form of persuasive instrument whereby generatingless pollution can save the polluter money. In the context of eutrophication, there are twobasic classes of economic instruments: fiscal and financial instruments and marketinstruments, including property rights instruments.

Fiscal and Financial Instruments.This is the most significant class of economic instruments and includes emission charges,product charges, subsidies, preferential tax treatment, and financial incentives.

Emission fees. Emission fees (also called effluent fees) involve charging polluters a feeper unit of pollutants generated. Thus if food-processing waste is being discharged into alake, the generator would pay a fee per unit of pollution emitted. Such a fee should notbe confused with a fine for emitting more than allowed. The idea behind this measure isthat there is no correct amount of pollution but, all other things equal, less pollution isbetter. It is always appropriate to send a signal to polluters to try to reduce pollution(though not at any cost). The emission fee makes discharging pollution a little less

attractive to the polluter. No matter what amount of pollution is generated, the pollutermust pay a fee to the regulatory body covering those emissions. Such fees are probablyless effective for controlling pollution that comes from government agencies or otherinstitutions that may be less concerned about costs or budget balancing. The fee will belower when the assimilative capacity of the water body has not been exceeded, comparedto the case where it has been exceeded.


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User fees. In the context of a municipal wastewater collection and treatment system, theusers of the system can be charged according to the load they place on the system.Clearly, a sewer use charge that is unrelated to the amount of waste generated (forinstance, a fixed monthly charge) provides little incentive to reduce wastewaterdischarges to the system. When proper financing of wastewater treatment is difficult, as

it is in many developing countries, it is particularly important to relate the charges paidby users to the cost of providing services to those users. If metering wastewatergeneration is too costly, charges can be based on closely related variables, such as wateruse or size of facility.

Product charges. A product charge is a charge on a good or service that is closely relatedto pollutant emissions. For instance, a charge per unit of fertilizer purchased by farmerswould be a product charge whereas a charge per unit of fertilizer runoff into a lake wouldbe an emission charge. It is easier to monitor fertilizer use than runoff and thus easier totax fertilizer than the pollutant emissions directly.

Subsidies. Although a fee placed on emitting sends a signal that emissions should beavoided, such fees are often politically difficult to institute. Those subject to the feesmay protest that they cannot afford them. This may be a particular concern in developingcountries that are trying to encourage industry. An alternative is to subsidize pollutionreduction. For instance, a food processing facility which has been emitting a certainlevel of nutrients can be paid for every unit of emissions reduced below the baseline. Theproblem with subsidies is that they require a source of funds, which may not be readilyavailable.

Market Instruments.Markets can be very effective for helping to efficiently manage resources. It issometimes possible to harness market forces to solve water and pollution managementproblems. For instance, markets can be established for the rights to use water forindustrial and agricultural use. Such a market assures that scarce water is used in thehighest value activities.

For managing the eutrophication of lakes, markets can be established in the form ofpermits to discharge nutrients into the environment. Under a tradeable permits system,the regulatory authority determines the total amount of emissions of nutrients into a givenlake and its tributaries during a year or other period. The agency allocates the totalallowed nutrient load among the various emitters in the region. Thus, if emitters are onlyemitting what is allowed, the pre-chosen overall level of emissions of nutrients will notbe exceeded. The problem is that some polluters may have a very difficult timecomplying with their ceiling on emissions. Others may have no trouble at all. If tradingamong emitters is allowed, those which have a difficult time with control will be able toacquire (buy) permits from those who find control easy. The one thing we can be sure ofis that the total amount of permitted emissions stays the same before and after trade.What is different is that the system is much more flexible with trading, giving pollutersmore options. The advantage of allowing trading is that the cost of pollution control is aslow as possible.


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Issues in Implementing Economic Instruments

The use of economic instruments is at the top of the agenda of the environmentalmanagement sector in an increasing number of developing countries and emergingeconomies all over the world. They are widely regarded as being economically efficient

and environmentally effective alternatives to direct regulatory instruments. In theory, byproviding incentives to control water pollution or other environmental damage, economicinstruments are believed to have lower compliance costs and can provide much neededrevenue for local government coffers (though not all economic instruments generaterevenue).

Administrative costs associated with economic instruments, however, may be high.Monitoring requirements and other enforcement activities remain as for traditionalinstruments, and additional administration efforts may be required to cope with thedesign and institutional changes arising from the implementation of economicinstruments, at least initially.

The following are some key findings of a study1 on the application of economicinstruments in eleven countries of Latin America and the Caribbean:

Economic instruments are widely used.

The primary historical role of economic instruments is to raise revenue. Otherpotential objectives, such as reduction of environmental impacts or improvingcost-effectiveness of regulations, have been under-emphasised or not attained.

Public awareness is low and uncertainty is high. There is a weak participation amongstakeholders, which poses a real constraint to the rapid implementation of complexmechanisms for the implementation of economic instruments.

Economic instruments can be an important, if not the only, means for introducing

some added efficiency to existing control mechanisms. The proposed scope must,however, match the institutional capacity to implement them. To this extent,approaches that introduce gradual and flexible reforms are more likely to be consistentwith ongoing institutional changes.

While the revenue collection task of economic instruments has been highlighted,there still exists a strong need to channel revenues to local authoritiesto assist inbuilding institutional capacity.

International donor agencies are prone to recommend solutions from the Organizationof Economic Cooperation and Development with little regard to institutional issues;to date most of the information flow regarding economic instruments has been of a"North-South" variety. An important opportunity has been missed to share

environmental management experiences among developing countries; increasedinformation sharingin a "South-South" dialogue will benefit all parties.

1 Motta, S., Ruitenbeek, J. and Huber, R., 1997. Applying economic instruments for

environmental management in the context of institutional fragility: The case of Latin America

and the Caribbean, in Finance for Sustainable Development: The Road Ahead, Proceedings of

the Fourth Group Meeting on Financial Issues of Agenda 21 held in Santiago, Chile, 1997, New

York, U.S.A.


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A common assumption regarding economic instruments is that they constitute a readysubstitute for out-dated or inefficient direct regulatory procedures. However, andcertainly initially, economic instruments should be considered complements to existingregulatory approaches, not substitutes.

Choosing Regulations: Benefit-Cost Analysis

In the previous section a variety of different instruments were considered for controllingeutrophication. In practice, a government agency will design a much more specific set ofregulations which draw from the broad classes of instruments. In fact, the agency mayhave several candidate "solutions" to the eutrophication problem, and a finely honed setof regulations or incentives to apply to the eutrophied lake in question. The problem thenarises of how to choose the best regulatory approach?

Benefit-Cost Analysis (BCA), also called Cost-Benefit Analysis, is a useful tool forassessing the economic effects of projects, policies or programs. Simply put, this

approach entails enumerating all significant benefits and costs of a given policy ormanagement objective. The purpose is to provide a filter that would systematicallyeliminate projects that do not provide enough benefit relative to their costs.

Implementing Benefit-Cost Analysis

It is important to realize that BCA has a very specific purpose: to help decision makerschoose among several very specific proposals for controlling a specific eutrophicationproblem. These may be new policies or modifications of old policies. BCA is not usedto study a problem or explore solutions to a problem. When an agency has winnoweddown its candidates for controlling a eutrophication problem to a few alternatives, BCAcan be used to help make a choice and help defend that choice in deliberations within andoutside the agency.

In implementing BCA, the first task is to enumerate the physical consequences of theseveral regulatory options under consideration. The second step is to convert thesephysical estimates into a common denominator. The costs of a policy that improveswater quality in a lake or reservoir would first include the monetary expenditure requiredto implement the policy and the necessary pollution controls. These expenditures includeany necessary investments (for example, investments in water treatment plants),operating costs (for example, dredging costs) and monitoring and evaluation costs. Costsrepresent resources that have to be diverted from productive uses elsewhere in theeconomy. The value of the foregone opportunities is the appropriate measure of the costof combating eutrophication. A commitment of resources to improving water quality mayaffect economic growth as well as affecting the distribution of economic welfare amongvarious social groups. For example, it may reduce investments in industrial developmentwhile also providing jobs for rural people. The consequences for growth and incomedistribution are particularly important in developing countries. It is important to realisethat costs need not involve any out-of-pocket expenditures. If the government owns landthat is used for a constructed wetland (see Chapter 2), then there is a cost associated with


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using that land, even though it was not purchased. The land is not unusable for otherpurposes; there is an opportunity cost of using it for the wetlands which is just as real asif it had been purchased.

Environmental costs are another set of costs that need to be taken into account. For

example, reducing eutrophication may reduce yields of certain fish species, which is anenvironmental cost. The value of the existence of a wide range of different species in aspecific water body or during a specific period of time also needs to be considered inbenefit-cost analysis.

Issues in Benefit-Cost Analysis

Benefit-cost analysis alone is not enough upon which to base a decision but providesimportant information for the decision making process. It can be used as a filter, rankingdevice or contribute to other forms of social and economic information. Whatever thecircumstances of the benefit-cost analysis application, it is important to ensure quality

control in the implementation of the procedure. Two important issues relating to qualitycontrol are: first, the principles are clearly specified for empirical benefit-cost analysisand are based on sound economic principles; and second, the benefit-cost analysisdocuments are available for public scrutiny to expose the improper use of theory andpractice.

Benefit-cost analysis can be applied to a spectrum of policy choices. For instance,eutrophication can be examined at the farm level, industry level, local level, State orProvincial level and Federal level. Each requires a different set of information about thebenefits and costs. Generally, the appropriate scope to use for a particular BCA is thatassociated with the agency doing the analysis or the reviewing agency. For instance if alake is shared by two countries and one of the countries is considering action, then costsand benefits are typically restricted to the single country, for the purposes of decision-making.

The estimation of costs is relatively simple compared the estimation of the benefits. Inmany cases a policy change has low costs but determining the benefits and orbeneficiaries can be difficult. This is particularly prominent when markets are notworking well or a market does not exist for the good in question. Benefits from naturalresource conservation are the gains that result from the sustainable uses of biodiversity.Presently, there is a serious lack of data available on the value of biodiversity. Theabsence of such data may induce people to assume that these values are small or eveninsignificant.

The benefits of a policy that reduces eutrophication might include an increase inrecreational activities, an increase in fish yields, improvements in human health, areduction in water treatment costs for potable water and increases in the aesthetic valuesof water based on appearance, taste and odor. It is useful to distinguish between privateor individual benefits and collective benefits. Private benefits are enjoyed by oneindividual while collective benefits are enjoyed simultaneously by many individuals.


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Many of the benefits associated with improved water quality are enjoyed collectively.Collective benefits are not easily included in markets and, accordingly, are difficult tomeasure.

Benefit cost analysis is typically done in two stages. First, the benefits and costs of a

given measure are calculated for each year that it is effective. Second, these are added upover the different periods of time to obtain an aggregate, or "net present value." This isdone by weighting ("discounting") benefits and costs at different points in time, with thefuture having slightly lower weights than the present. If the net present value is positive,that is, present value benefits exceed present value costs, the policy makes economicsense.

Discounting is done so that benefits and costs occurring at different times can beaggregated and expressed in composite form. There are two justifications for discounting.First, most consumers consider present day benefits to be more valuable than future. Thisexplains the willingness to borrow funds and pay interest. Second, resources invested

now will increase well-being in the future. This explains the willingness to borrow fundsand pay interest to invest in new businesses and technologies. In both cases, people arewilling to pay a premium in the future to have access to funds in the present. Thediscount rate, r, is the premium they are willing to pay, expressed as a percentage over aspecified period. Funds received today are worth, at the end of the first period, a total of(1+r) times the amount of funds. Equivalently, an amount of funds to be received at theend of the period are worth 1/(1+r) times that amount at the beginning of the period.

While discounting is a common procedure, the issue of what is an appropriate discountrate to use for public projects can be debated. Since higher discount rates disadvantageinvestments that take many years to pay off, the choice of a discount rate can directlyinfluence the choice of policies to implement. For investments in projects that yieldtangible products and services, such as waste treatment plants, dams and recreationalfacilities, the appropriate discount rate should be guided by market rates, at least equal tothe interest rate on government bonds. For policies or programs, particularly those havingconsequences lasting well beyond the typical 10 to 25 year life spans of most privatesector investments, a lower discount rate may be warranted, reflecting the fact thatsociety may be less impatient than the private sector. This is also based on the idea thatconsumption by distant generations is a public good and current policies should take thatinto account.

The treatment of inflation is another issue in the determination of a discount rate. Thenominal rates observed in the market place include a component that reflects expectedinflation. An interest rate that removes the inflation is called a "real" interest or discountrate. Real discount rates between 3 and 8 percent are most often used in benefit-costanalysis in developed countries while in developing countries it can be as high as 10 or12%. Often, rates used by government agencies or international organisations such as theWorld Bank are used as benchmarks. Finally, in a benefit-cost study, a sensitivityanalysis should be done to see how net benefits are affected by different discount rates.


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Examples of Benefit-Cost Analyses in Lake Management.

At present, the average cost of treatment of water for drinking or public supplies amountsto US$ 10 per thousand m. However, the cost decreases to US$ 2 per thousand m whenthe water treated is of good quality. Therefore, the costs of water treatment increase in

eutrophic systems. There are also different indirect economic effects of eutrophication,such as the loss of days of work from health failures due to exposure or drinking of waterwith algal toxins.

Economic losses due to eutrophication of lakes and reservoirs may be severe. In one casein Brazil, in So Paulo State, a devaluation of 50% of the price of properties occurred as aconsequence of algal blooms and macrophyte growth, and a loss of recreational capacityof a water body. Bad odors and danger of toxicity contributed to this devaluation. On theother hand, at a small recreational reservoir, also located in So Paulo State, waterquality, which was maintained in good condition during 25 years, stimulated economicinvestment in tourism, provided job opportunities, and created a booming regional

industry. The reservoir, which is only 7 km large, has stimulated an investment of US$250 million in 25 years, showing the clear advantage of prevention over remediation. Incontrast, the recovery of the Tiet River in So Paulo City cost an estimated US$ 4billion over 10 years.

The need to control and manage the effects of urban, industrial and agriculturaldevelopment on Japans largest lake, Lake Biwa, led to the formation of the Lake BiwaComprehensive Development Project. Although the basic objective of the project was topromote development of the Keihanshin region by providing additional water, otherimportant objectives included the conservation of the natural environment, the promotionof public welfare, and the restoration of water quality. The planned cost of the projectwas Japanese Yen 426,637 x 106 in 1971. However, the actual cost of the project, carriedout from 1972 to 1992 was Japanese Yen 1,524,850 x 106.

Under controlled eutrophic conditions, aquaculture in lakes can be a source of revenueand of job opportunities. Benefit-cost analysis was carried out to evaluate the economiceffect of fertilization of Lake Kootenay, British Columbia, Canada, in 1995 (K. Ashley,Ministry of Fisheries, British Columbia, personal communication). The surface area ofthe lake is approximately 390 km2. Total costs for fertilization of the lake were estimatedat Can$ 511,000. Of this sum, the cost of a liquid fertilizer and its application to the lakewas Can$ 310,410. The rest of the total cost (i.e., Can$ 199,590) was spent on sampling,monitoring, travel and data processing. Estimated gross benefit for the same year wasCan$ 2,000,000. Calculated cost per km2 was Can$ 1,293, and the benefit was Can$5,063 per km2. The total cost is expected to decrease in 1999/2000 to approximately Can$300,000, and therefore the benefit-cost ratio will be greater than that of 1995.

Measuring Costs and Benefits of Reducing Eutrophication

Measuring the benefits and costs of an improvement in water quality is often difficult.First, for a complete analysis, all relevant benefits and costs have to be measured. If some


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consequences cannot be monetized, then analysis becomes more complex, thoughfeasible. The effects on all parties concerned have to be taken into account. Second, thephysical benefits and costs have to be measured in monetary units. Some environmentalgoods and services are marketed and thus have prices associated with them, for example,commercial fishing. There are methods for estimating costs and benefits in such cases.

These "market-based methods" involve tallying the payments that consumers actuallymake for better water, better recreational sites, more desirable fish species, or otherattributes of a cleaner water body. Also, the cost savings to consumers such as those dueto fewer illnesses and lower use of water filters have to be taken into account. Othervalues associated with improved water quality, such as aesthetic values and speciesdiversity have no connections to markets. These values must be measured by othermeans.

The concept of "willingness-to-pay" (WTP) is widely used to represent how much of aperson's resources they would be willing to contribute to solving an environmentalproblem. It might more appropriately be called "willingness-to-sacrifice." This is a

subtle point because in general we are not asking a person to pay, only trying todetermine the maximum amount of resources they would divert from other worthwhileactivities to enhance environmental quality. In a market economy, WTP is a relativelyeasy concept to grasp. However, a monetary measure of WTP is meaningless to asubsistence farmer.

Economic effects of eutrophication and types of benefits derived from reducingeutrophication are outlined in Table 5. Common economic methods used to measuredifferent types of benefits outlined in the table and commonly used valuation techniquesare discussed below.

Market-based Methods

Market-based methods are used when people make choices in the market place amonggoods or services that have some environmental characteristics. The observed marketchoices can be used to estimate the value consumers place on environmental factors. Forexample, when people rent or buy property, one of the factors they may consider includeswater quality in the area. The price they pay for a particular property will reflect thevalue they place on the environmental qualities, as well as other characteristics of theproperty. By statistically analyzing differences in prices and differences inenvironmental quality, it is possible to estimate peoples WTP for particularenvironmental qualities as distinct from other characteristics of the property such as lotsize and location. This method is known as the "hedonic" method.

A second method that uses market information is called the "travel cost method," whichis typically used to estimate value of recreation sites. Visitors to such sites incur time andtravel expenses, which is a proxy for price and reflects the willingness to pay for thecharacteristics of the site. The method uses data on the type and number of recreationtrips that people make to different sites at varying levels of expenses. Statistical analysisis used to estimate the relationship between the attributes of the trips and travel costs.


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This is a useful method when trying to understand the benefits of improvingenvironmental quality at p

Planning and Management of Lakes and Reservoirs

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