Future of the Big Darby Future of the Big Darby WatershedWatershed

Steven Gordon

December, 2001

Where are we going?Where are we going?

Current status of stream healthHow development trends will impact itPreserving the quality

– What do we need to do?– How can we get there?

The Good NewsThe Good News

The Big Darby is still a very high quality stream

Data show continued good health in most areas

We have an opportunity to keep it that way

IBI Status Before 1995# Very Poor# Poor# Good# Very Good# Excellent

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Status of Fish Communityin Big Darby Watershed before 1995

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IBI Status Since 1995# Very Poor# Poor# Good# Very Good# Excellent

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IBI Status Since 1995

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IBI Status Before 1995

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# Good# Very Good# Excellent

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Status of Fish Communityin Big Darby Watershed since 1989

Impacts of TrendsImpacts of Trends

Noticed that there are several problem areas where deterioration of quality has occurred

What is this related to?How might it change in the future?

Model of IBI in ECBPModel of IBI in ECBP

Eastern Cornbelt Plains Ecoregion

Major Differences Among Major Differences Among WatershedsWatersheds

Differences in habitat quality– Measured by components of QHEI (Qualitative

Habitat Evaluation Index)– Reflect changes in riparian zone quality

Differences in point source pollutionDifferences in land use/non-point source

pollution– Urban land use a key

Web-Based ToolsWeb-Based Tools

Http://tycho.cfm.ohio-state.eduHow does this fit with current trends?

– Analysis done by my students last Spring– Study sponsored by the Darby Creek Association

Urban growth in the basin is substantialA reasonable forecast shows major

additional growth

Predicted IBI with Increases in Urban Area and decreased Pool and Substrate

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Obs 10 20 30 40 50

Years

IBI

Sco

re Point 1Point 2Point 3Point 4Point 5Point 6

Growth Rate AssumptionsGrowth Rate Assumptions

Growth rate (not absolute number of persons) was held constant with the following assumptions:– Extremely high growth rate areas would ‘fill

up’ with people and growth will decline– Areas adjacent to high growth regions will have

an increased rate of growth– No growth controls are in place in order to

restrict development anywhere in the watershed

Rates of Population ChangeRates of Population Change

Population Change– Forecasting model

based on population rates of change from 1990 to 2000

– Rates of change varied from -31% to 211%, but most between -2% and 40%

Population Growth from 1990 to 2000

5% growth and below5 to 20%20 to 50%51 to 80%80% and above

Growth Rate AssumptionsGrowth Rate Assumptions

Rates of change that were significantly high (80% to 211%) were halved because of high growth and only moderate projected county growth by the ODOD

Tracts within Counties with high anticipated growth were increased (12.5% to 25% based on ODOD data) depending on adjacency to historically high growth tracts

ResultsResultsPopulation Growth from 1990 to 2000

5% growth and below5 to 20%20 to 50%51 to 80%80% and above

Population Growth from 2000 to 2010

5% growth and below5 to 20%20 to 50%51 to 80%80% and above

Results ContinuedResults ContinuedPopulation Growth from 2000 to 2010

5% growth and below5 to 20%20 to 50%51 to 80%80% and above

Population Growth from 2010 to 2020

5% growth and below5 to 20%20 to 50%51 to 80%80% and above

Comparison with ModelComparison with Model

Model forecast about a 25% growth with lower base

Population forecast pushes rates to 50% for some tracts

Will accelerate deterioration in growth areasProbably have a time-scale of 10-15 years

unless something changes

What needs to be done?What needs to be done?

Action by all communities– From cities to townships to counties– From farmers to residents to developers

A combination of approaches– Protect and improve the riparian zone– Best management practices for all uses for all

areas– Reduction in total growth

Consequences of InactionConsequences of Inaction

Continuing decline of stream quality– Loss of communities– Increased flooding

Loss of prime farmland– Loss of agricultural communities/mix– Loss of open space

Increases in congestion and other urban problems

Possible ActionsPossible Actions

Riparian zone protectionBMP controls in zoning and subdivisionStrict enforcementConservation easements or other land

banking techniques

How do we get there?How do we get there?