ROCK CREEK - CRESTA RECREATIONAL RELEASE FLOW...

ROCK CREEK - CRESTA RECREATIONAL RELEASE FLOW

MACROINVERTEBRATE STUDY REPORT

Rock Creek - Cresta Project (FERC Project No. 1962)

Final

Prepared By:

December 2011

Final Recreational Release Flow Macroinvertebrate Study Report i December 2011

Rock Creek-Cresta Project, FERC No. 1962 © 2011, Pacific Gas and Electric Company

TABLE OF CONTENTS

Section Title Page

Executive Summary ...................................................................................................................ES-1

1.0 Introduction ......................................................................................................................1

1.1 Settlement Agreement ......................................................................................................1

1.2 Previous Studies ...............................................................................................................2

1.2.1 Recreation Flow Specific Studies .....................................................................................2

1.2.2 California Stream Bioassessment Procedure (CSBP) Studies .........................................3

1.3 Goals and Objectives ........................................................................................................3

1.3.1 Study Goals and Objectives..............................................................................................3

2.0 Project Description ...........................................................................................................4

3.0 Approach ..........................................................................................................................6

3.1 General Approach .............................................................................................................6

3.1.1 The Environmental Setting ...............................................................................................7

3.1.2 Questions to be addressed and Hypotheses to be Tested................................................11

3.1.3 Phasing of Work .............................................................................................................20

3.2 Reach Selection ..............................................................................................................21

3.2.1 Treatment Reach .............................................................................................................22

3.2.2 Reference Reaches..........................................................................................................22

3.2.3 Schedule .........................................................................................................................26

4.0 Methods ..........................................................................................................................27

4.1 Study Design ..................................................................................................................27

4.1.1 Design and Sampling Sites .............................................................................................27

4.1.2 Before-After ...................................................................................................................28

4.2 Measurement Approach .................................................................................................28

4.2.1 Key Macroinvertebrates .................................................................................................29

4.2.1.1 Selection of Key Insect Genera and Other Taxa ............................................................29

4.2.1.2 Density and Abundance ..................................................................................................29

4.2.1.3 Population Size Structure ...............................................................................................30

Final Recreational Release Flow Macroinvertebrate Study Report ii December 2011


4.2.2 Macroinvertebrate Biomass ............................................................................................30

4.2.3 Periphyton/Production/Seston ........................................................................................30

4.3 Effect Thresholds ...........................................................................................................32

4.3.1 Hypothesis Testing for Before-After Recreational Flow Releases .................................34

4.4 Field Methods .................................................................................................................34

4.4.1 Habitats Sampled ............................................................................................................34

4.4.2 Macroinvertebrate Sampling ..........................................................................................34

4.4.3 Periphyton Sampling ......................................................................................................35

4.4.4 Seston Sampling .............................................................................................................35

4.4.5 Physical Measurements ..................................................................................................36

4.5 Laboratory Analyses .......................................................................................................36

4.5.1 Taxonomic Analysis .......................................................................................................36

4.5.2 Chlorophyll a ..................................................................................................................37

4.5.3 AFDM ............................................................................................................................38

4.6 Analytical Approach .......................................................................................................38

4.6.1 Data Handling and Reporting .........................................................................................38

4.6.2 Data Evaluation Conducted ............................................................................................39

4.6.2.1 Analysis of Insect Lengths..............................................................................................45

5.0 Results ............................................................................................................................52

5.1 2007 ................................................................................................................................52

5.1.1 Physical Conditions ........................................................................................................52

5.1.2 Macroinvertebrate Taxa .................................................................................................53

5.1.2.1 Macroinvertebrate Densities ANOVA ...........................................................................53

5.1.2.2 Macroinvertebrate Densities Paired t-Test .....................................................................54

5.1.2.3 Macroinvertebrate Densities Linear Analysis ................................................................55

5.1.2.4 Comparison of Variances of Macroinvertebrate Taxa ...................................................57

5.1.3 Macroinvertebrate AFDM ..............................................................................................58

5.1.3.1 Macroinvertebrate AFDM ANOVA ...............................................................................59

5.1.3.2 Paired t-Test ...................................................................................................................60

5.1.3.3 Linear Analysis ...............................................................................................................60

Final Recreational Release Flow Macroinvertebrate Study Report iii December 2011


5.1.4 Functional-Feeding Groups ............................................................................................61

5.1.4.1 Functional-Feeding Groups Density ANOVA Comparisons .........................................61

5.1.4.2 Functional-Feeding Groups Density Paired t-Test Comparisons ...................................61

5.1.4.3 Functional-Feeding Groups Density Linear Analysis Comparisons ..............................62

5.1.5 Habit Groups ..................................................................................................................63

5.1.5.1 Habit Groups Density ANOVA Comparisons ...............................................................63

5.1.5.2 Habit Groups Density Paired t-Test Comparisons .........................................................63

5.1.5.3 Habit Groups Density Linear Analysis Comparisons .....................................................64

5.1.6 Macroinvertebrate Length ..............................................................................................64

5.1.6.1 Distribution Comparison ................................................................................................64

5.2 2008 ................................................................................................................................68

5.2.1 Physical Conditions ........................................................................................................69

5.2.2 Macroinvertebrate Taxa .................................................................................................70

5.2.2.1 Macroinvertebrate Densities ANOVA ...........................................................................71

5.2.2.2 Macroinvertebrate Densities Paired t-Test by Velocity Lane .........................................74

5.2.2.3 Macroinvertebrate Densities Linear Analysis ................................................................76

5.2.2.4 Comparison of Variances of Macroinvertebrate Taxa ...................................................83

5.2.3 Macroinvertebrate AFDM ..............................................................................................84

5.2.3.1 Macroinvertebrate AFDM ANOVA ...............................................................................84

5.2.3.2 Macroinvertebrate AFDM Paired t-Test by Velocity Lane ............................................87

5.2.3.3 Macroinvertebrate AFDM Linear Analysis ....................................................................89

5.2.4 Functional-Feeding Groups ............................................................................................92

5.2.4.1 Functional-Feeding Groups Density ANOVA ...............................................................92

5.2.4.2 Functional-Feeding Groups Density Paired t-Test by Velocity Lane .............................94

5.2.4.3 Functional-Feeding Groups Density Linear Analysis ....................................................95

5.2.5 Habit Groups ................................................................................................................100

5.2.5.1 Habit Groups’ Density ANOVA ..................................................................................100

5.2.5.2 Habit Group’s Density Paired t-Test by Velocity Lane ................................................102

5.2.5.3 Habit Group’s Density Linear Analysis .......................................................................103

5.2.6 Macroinvertebrate length..............................................................................................108

Final Recreational Release Flow Macroinvertebrate Study Report iv December 2011


5.2.7 Periphyton ....................................................................................................................122

5.2.7.1 Periphyton Chlorophyll a .............................................................................................122

5.2.7.2 Periphyton AFDM ........................................................................................................125

5.2.8 Seston AFDM ...............................................................................................................127

6.0 Discussion ....................................................................................................................130

6.1 Introduction to the Discussion of Hypotheses Testing .................................................134

6.2 Hypotheses ...................................................................................................................137

6.2.1 Hypotheses 1, 2 and 3: Hypothesis 1) Attached filamentous algae will decrease;

Hypothesis 2) Epilithic diatoms will increase and Hypothesis 3) Periphyton

standing-crop biomass will decrease ............................................................................137

6.2.2 Hypothesis 1 - Periphyton Chlorophyll a .....................................................................139

6.2.3 Hypothesis 3 - Periphyton AFDM ................................................................................141

6.2.4 Conclusion of Hypotheses 1, 2 and 3 ...........................................................................143

6.2.5 Hypothesis 4 Epilithic Benthic Macroinvertebrates will Decrease ..............................144

6.2.5.1 Epeorus .........................................................................................................................144

6.2.5.2 Glossosoma ..................................................................................................................146

6.2.5.3 Leucotrichia pictipes ....................................................................................................147

6.2.5.4 Protoptila .....................................................................................................................149

6.2.5.5 Zaitzevia .......................................................................................................................151

6.2.5.6 Conclusion of Hypothesis 4 .........................................................................................152

6.2.6 Hypothesis 5 Grazers will Decrease .............................................................................153


6.2.7 Hypotheses 6 Benthic Macroinvertebrates that are Swimmers will Decrease .............155

6.2.7.1 Swimmers .....................................................................................................................156

6.2.7.2 Acentrella .....................................................................................................................157

6.2.7.3 Baetis tricaudatus .........................................................................................................159

6.2.7.4 Camelobaetidius ...........................................................................................................160


6.2.8 Hypothesis 7 Abundance of Benthic Macroinvertebrates that are Clingers will

Remain Approximately Unchanged .............................................................................163

Final Recreational Release Flow Macroinvertebrate Study Report v December 2011


6.2.8.1 Clingers ........................................................................................................................163

6.2.8.2 Hydroptila ....................................................................................................................165

6.2.8.3 Ochrotrichia .................................................................................................................166

6.2.8.4 Optioservus ...................................................................................................................167

6.2.8.5 Serratella ......................................................................................................................169


6.2.9 Hypothesis 8 Predators will remain approximately the same .......................................171

6.2.9.1 Predators .......................................................................................................................171

6.2.9.2 Hemerodromia..............................................................................................................173

6.2.9.3 Isoperla .........................................................................................................................174

6.2.9.4 Rhyacophila malkini .....................................................................................................176

6.2.9.5 Conclusion Hypothesis 8 ..............................................................................................177

6.2.10 Hypothesis 9 Food will increase for macroinvertebrates that are in the filter-

feeding functional-feeding group during a recreational flow release. ..........................178

6.2.10.1 Seston Availability (Hypothesis 9a) .............................................................................178

6.2.10.2 Conclusion Hypothesis 9a ............................................................................................180

6.2.10.3 Small Size larvae in the Filter-feeding functional group Hypothesis 9a. .....................180

6.2.10.4 Conclusion Hypothesis 9a - small size larvae ..............................................................186

6.2.10.5 Conclusion Hypothesis 9a - large size larvae ...............................................................190

6.2.10.6 Hypothesis 9b Alternate. However, the filter-feeding group may also be

displaced during recreational flow releases, therefore, a decrease may occur. ............190

6.2.10.7 Conclusion Hypothesis 9b Alternate ............................................................................198

6.2.11 Hypothesis 10 Increased food for deposit feeders will result in their increased

growth. ..........................................................................................................................199

6.2.12 Hypothesis 11 Mean individual size will decrease for easily disturbed species. .........217

6.2.13 Hypothesis 12 Total macroinvertebrate biomass will show a short-term

decrease. .......................................................................................................................226

6.2.14 Hypothesis 13 Total macroinvertebrate biomass will show a long-term increase. ......229

6.2.14.1 Hypothesis 14 Certain macroinvertebrate taxa should be more responsive to the

recreational flow releases than others. ..........................................................................231

Final Recreational Release Flow Macroinvertebrate Study Report vi December 2011


7.0 General Summary and Recommendations ...................................................................234

7.1 Experimental Design ....................................................................................................234

7.2 Ecosystem and Faunal Responses ................................................................................237

8.0 References ....................................................................................................................239

TABLES AND FIGURES

Tables – 2007

Tables – 2008

Figures – 2007

Figures – 2008

APPENDICES

Appendix A Detailed Methods

Appendix B 2007 Physical Measurements and Habitat Information

Appendix C 2008 Physical Measurements and Habitat Information

Appendix D Consultation Documentation

Final Recreational Release Flow Macroinvertebrate Study Report ES-1 December 2011


EXECUTIVE SUMMARY

ES 1.0 INTRODUCTION

The 2001 license for Pacific Gas and Electric Company's (PG&E) Rock Creek-Cresta

Hydroelectric Project, FERC Project No. 1962 (Project), contains License Condition 17, which is

entitled “Recreation and Pulse Flow Biological Evaluation”. This condition required PG&E to

develop a Flow Evaluation Plan in consultation with the Rock Creek-Cresta Ecological Resource

Committee (ERC) and the United States Department of Agriculture-Forest Service (FS) within

one year of License issuance. The intent of the original study plan was to make an interim

evaluation to determine if the recreational flow releases have either a beneficial, neutral, or no

significant adverse effect on the aquatic biota, as determined by the ERC and the FS1. One

component of the Flow Evaluation Plan was to determine the effects of the recreation flow

releases on the stream benthic macroinvertebrate community. Following a three-year data

collection in 2002 through 2004 and analysis effort, the ERC and FS could not determine any

conclusive effects (beneficial, neutral, or no significant adverse) of recreation flow releases on

macroinvertebrates. Because of failure to provide evidence of conclusive effects, a second study

was developed and conducted within a framework of specific well-defined goals, objectives and

hypothesis in 2007 and 2008. This report is the outcome of that effort.

This report is based on a study that was developed and conducted in consultation with

macroinvertebrate and aquatic ecology experts from the University of California, Berkeley, and

the University of Montana under guidelines of the Project License Condition 17 and the Project

Settlement Agreement. The intent of this study was to collect macroinvertebrate and related

biological (e.g. periphyton, seston), habitat, and physicochemical data specifically related to

recreational flow releases and their potential affects on river reaches. The study plan included

treatment (recreational flow reaches) as well as in reference reaches in a manner appropriate to

1 The specific language from the license, page 52 of the appendix reads, “If, after 3 years of data collection and assessment, either beneficial, neutral, or no significant adverse effects (as determined by the ERC and Forest Service) are observed, recreation flow releases days will be added as supported by on-water recreational use monitoring in Paragraph E, Condition 16. Days will be adjusted after that period as supported by ecological and on-water recreational use monitoring.”



address the hypotheses developed in the study plan approved by the ERC (Resh et al. 2007,

2008).

ES 2.0 PROJECT DESCRIPTION

The Project includes the Rock Creek and Cresta Developments located on the North Fork Feather

River (NFFR). The Rock Creek-Cresta Project was built between 1948 and 1950 and began

operation in 1950. Major developments in the NFFR began with the construction of Canyon

Dam in 1914 and expansions of Lake Almanor in 1916 and 1927. Butt Valley Reservoir was

constructed to generate power using Lake Almanor storage and was completed in 1924 and

discharges to the NFFR through the Caribou 1 and 2 powerhouses. In 1958, Belden Forebay was

constructed downstream of the Caribou powerhouses and provides flow to the Belden

Powerhouse located downstream on Yellow Creek. Instream flows are released to the NFFR

from Belden Dam, currently through the Oak Flat Powerhouse, which was completed in 1985.

The Rock Creek development is located downstream of Yellow Creek. It is the upstream

development of the Rock Creek-Cresta Project, and consists of: the Rock Creek reservoir with a

gross storage capacity of 4,400 acre-feet and a surface area of 118 acres; a 126-foot-high, 567-

foot-long dam; an intake structure within the reservoir about 100 feet upstream of the dam; a

tunnel approximately 6.5 miles long; two penstocks, 906 and 938 feet long, respectively; and a

powerhouse containing two turbine-generator units with a total installed capacity of 114,000

kilowatts (kW). There is an 8.4-mile-long bypassed reach between the reservoir and

powerhouse.

The Cresta development is the next reservoir-forebay development downstream of the Rock

Creek development (Figure 2-1). It consists of: the Cresta reservoir with a gross storage capacity

of 4,140 acre-feet and a surface area of 95 acres; a 114-foot-high, 378-foot-long dam; an intake

structure within the reservoir about 100 feet upstream of the dam; a tunnel almost four miles

long; two penstocks, 800 and 775 feet long, respectively; a powerhouse containing two turbine-

generator units with a total installed capacity of 71,000 kW; and a 52-foot-long tailrace. There is

a 4.9-mile-long bypassed reach between the reservoir and powerhouse.



ES 2.1. Goals and Objectives

ES 2.1.1. Study Goals and Objectives

The objective of this Study was to determine the nature of, and potential beneficial, neutral, and

significant adverse effects of, recreational flow releases on the benthic macroinvertebrate

community and primary producers that may relate to the goals established in the Rock-Creek-

Cresta Settlement Agreement. This Study was based on testing specific hypotheses using well-

known indicator macroinvertebrate taxa, functional-feeding groups, habit groups, food sources,

and primary producers to identify ecologically beneficial, neutral, or significant adverse effects

resulting from recreational flow releases. The hypotheses are stated in a formal statistically

testable structure. Statistical and ecological effect thresholds are established for significance.

The goal of this Study was to provide sufficient data and analysis through a carefully designed

study to relate the effects of recreational flow releases on the macroinvertebrate community and

primary producers. Results should assist the ERC and FS with the management of recreational

flow releases and evaluation of the beneficial, neutral, and adverse effects to the benthic

macroinvertebrates and primary producers.

ES 2.2. Approach

ES 2.2.1. General Approach

Our approach in evaluating the effects of recreational flow releases on macroinvertebrates in the

NFFR was to focus on highly specific research questions based on accepted ecological theory and

empirical observations in macroinvertebrate and river ecology. These questions were posed as

testable hypotheses and an experimental design was developed and executed employing

recognized protocols, techniques and quantifiable measures. These questions address effects on:

frequency of occurrence and density of abundant macroinvertebrate taxa; abundance of taxa

recommended by local anglers as dominant fish-food organisms; the population and size

structure of the abundant fish food taxa; the amount of food available to the primary consumers

from the primary producers (the algae and diatoms) of the food web; and possible secondary

effects of higher discharge and increased substratum shear-stress resulting in the reduction of



filamentous algae and clearing space for diatomaceous periphyton and macroinvertebrates to

colonize. In each case, comparisons were made for conditions before and after recreational flow

releases, and in comparison with a reference site or sites. Comparisons included both analyses

focused on individual recreational flow releases and cumulative effects of the flow releases over

the course of the summer-fall period, for each year studied.

The stream organisms that occur in the NFFR are the evolutionary result of physical, chemical,

and biological components of the regional environment that have been shaped by the sequential,

predictable, seasonal flooding and extended base flows that occur over each annual cycle. These

hydrological patterns are the result of the location of this river system in California’s

Mediterranean climate region (Gasith and Resh 1999, Bonada et al. 2006). The summer-fall

period of lower and relatively stable or decreasing flows of this climate has influenced the

evolution of these benthic organisms. Prior to hydroelectric development, summer-fall low flows

were considerably higher than those present today (PG&E 2002b), but the general pattern typical

of Mediterranean climate streams was present. Moreover, the evolution of these organisms were

influenced as a metapopulation, (i.e., populations occurring in different streams with interchange

of breeding adults and their gene pools) rather than as taxa occurring in individual streams and

rivers of this region. The adaptation to the conditions of wet season high flows and dry season

low flows, whether these were stable or continuing to decrease until the onset of rains in autumn,

influences their response to departures from this Mediterranean hydrologic pattern, such as

caused by recreational flow releases in summer and early autumn.

Because the NFFR is regulated, flow patterns no longer follow the Mediterranean climate

hydrologic regime that shaped the evolution of the benthic macroinvertebrates of this region.

High winter flows still occur, but these may be attenuated by the operations of the dams and

water capture in reservoirs in the NFFR system. Both the Rock Creek and Cresta reaches are

regulated, although their tributaries are not. The UNF reach is only partially regulated and

receives unregulated flow from the East Branch North Fork Feather River (EBNFFR). In

addition, there are reduced flows occurring over the summers compared to the pre-development

period, because of the regulation and storage of flows originating from surface runoff and springs

located upstream, that are now below the surface of the current Lake Almanor, or intercepted by



the lake, respectively. However, in general, while flows in the study reaches were considerably

greater during the late summer than today, historically these flows were steady or declining

during the summer and fall. Therefore, we would expect species present during the current base

flow of summer and early autumn to be vulnerable to short-term shifts from base flow to high

flows that do not typically occur during this dry-season period and for which the

macroinvertebrate species of these reaches are not adapted.

Recreational flow releases have the potential to result in changes to the environmental conditions

and their spatial distribution within the stream to which some organisms currently present may

not be well adapted. However, these flows also may provide some benefits to the lotic ecosystem

and some of its inhabitants. These potential benefits are related to increased shear-stress created

by increased depth and flow velocity that result from increased discharge. For example, with

increased shear-stress may come the clearing of filamentous algae from substrate that results in

opening of space for diatom-dominated periphyton (a more nutritious food source than the

former) to colonize, the transport of food materials for filter-feeding organisms, and the

enhancement of feeding conditions for certain macroinvertebrates.

Indeed, some benthic macroinvertebrate taxa may be more sensitive to recreational flow releases

than others, or may respond in completely different ways depending on flow sensitivities, habitat

utilization, morphological structures, or trophic relations. Further, benthic macroinvertebrates

represent important components of the riverine food web, including food for fish, amphibians,

and terrestrial biota that use the river corridor. Likewise, numerous taxa are sensitive to flow

magnitudes, and thus are indicative of a broader response. For these reasons, rather than study

the effects of recreational flow releases across the entire benthic macroinvertebrate community,

we concentrated on specific macroinvertebrate taxa as representatives of specific trophic groups

or particular habits ad habitats. We posed a series of a priori hypotheses regarding the potential

effects of recreational flow releases on the Rock Creek reach (See Section 3). The hypotheses

included the following:

1. Attached filamentous algae will decrease.

2 Epilithic diatoms will increase.



3 Periphyton standing-crop biomass will decrease.

4 Epilithic benthic macroinvertebrates will decrease.

5 Grazers will decrease.

6 Benthic macroinvertebrates that are swimmers will decrease.

7 Abundance of benthic macroinvertebrates that are clingers will remain approximately

unchanged.

8 Predators will remain approximately the same.

9 Food will increase for macroinvertebrates that are in the filter-feeding functional-

feeding group during a recreational flow release.

10 Increased food for deposit feeders will result in their increased growth.

11 Mean individual size will change for easily disturbed species.

12 Total macroinvertebrate biomass will show a short-term decrease.

13 Total macroinvertebrate biomass will show a long-term increase.

14 Certain macroinvertebrate taxa should be more responsive to the recreational flow

releases than others.

The hypotheses were evaluated based on comparing the condition of the aquatic biota after each

recreational flow release to their condition before each flow release. This was done by the

collection of samples of the density of macroinvertebrates, macroinvertebrate ash free dry mass

(AFDM), periphyton AFDM, chlorophyll a, and seston AFDM. Recreational flow releases

occurred in the Rock Creek reach of the NFFR, which was the treatment reach for evaluation of

effects from before to after the recreational flow releases. Two reference reaches were selected

for comparisons with the Rock Creek reach. These reaches were similar in physical

characteristics and aquatic biota to the Rock Creek reach. We considered several reference

reaches for use in the study. Among these were the Cresta Reach, the Poe Reach, the EBNFFR,

and the Upper Belden Reach NFFR (upstream of the East Branch confluence NFFR), the Lower

Belden Reach of the NFFR upstream of Yellow Creek and downstream of the confluence of the



EBNFFR (Upper North Fork [UNF]), and two sites in the Middle Fork Feather River. Based on

analyses of biological and physical characteristics, as discussed in the study plan (Resh et al.

2007, 2008); we selected the UNF and Cresta reaches as reference reaches. The Cresta reach,

located downstream of the Rock Creek reach is the most similar to the treatment reach in terms

of the characteristics examined. During the two years of this study, no recreational flow releases

occurred in this reach, and the hydrograph indicates that the releases from the Rock Creek reach

did not affect the flow of the Cresta reach. In contrast, the UNF differed in summer flows and

temperatures, and the insect community, but it was considered important as a reference reach

representing a partially unregulated part of the river.

ES 2.3. Effect Thresholds

Reductions in abundance of macroinvertebrates are widely used as an indicator of impact (Resh

et al. 2006). The Mekong River Commission (2007) recently conducted an international review

of how reductions in benthic macroinvertebrate abundance are an indicator of change in the

ecological health of river systems. Based on this review, they chose a 40 percent reduction as a

threshold indicator of harm to the river ecosystem. The basis for deciding whether differences

resulting from comparisons made under the proposed study plan are sufficiently large to be

significant for decision-making is based on a review of the literature and the experience of the

authors. In this study, we established an a priori level of 50 percent change in density

(abundance or other appropriate basis) of key macroinvertebrate taxa as a threshold that would

strongly suggest an impact to ecological health of the river and thus have ecological importance.

The 50 percent reduction chosen as an indicator of significant adverse effect is more

“conservative” than the figure selected by the Mekong River Commission. We also decided that

for the purpose of this study, a difference of this magnitude should be detectable at a statistically

significant alpha=0.05. Therefore, a statistically significant (p≤0.05) difference of 50 percent or

more represents a difference of ecological significance and unlikely to be the result of random

chance alone. The change also was required to be in the direction (i.e., increase or decrease) in

the posed a priori questions and hypotheses.



Some of our hypotheses suggested beneficial consequences of recreational flow releases, whereas

others would suggest adverse effects. See Section 4.6 for further explanation of the analytical

approach.

ES 2.4. Study Design

We conducted the study during 2007 and 2008. During 2007, data collection occurred in August

and September, but did not include the first recreational flow release of the year, in July. There

were three recreational flow releases in 2008; early August, late August, and September. The

Study included all three of these recreational flow releases.

Data collection occurred in two phases. In 2007, the Study focused exclusively on

macroinvertebrates. In 2008, data were collected for macroinvertebrates, seston, periphyton

AFDM, and chlorophyll a.

The overall study design is based on a stratified random sampling design. In each reach studied,

both for the treatment and reference reaches, we focused our sampling on riffle/run habitats.

Each riffle/run habitat reach was divided into three randomly-selected transects for each

sampling event. In 2007, each transect was divided into three equal width-segments. Two of the

width segments were located adjacent to each shoreline and one segment represented the center

third of the channel. Each sampling location was selected randomly across the transects within

each segment. Each of the riffle/run habitats was sampled during each sampling event.

In 2008, in collaboration with the ERC and FS, we modified the stratification protocols to better

account for the observed variability of macroinvertebrate densities. Each transect was stratified

into three velocity lanes, based on the measurement of a velocity profile along the transect. The

transect was divided into three velocity lanes: low, medium, and high velocities, respectively.

This stratification allowed us to evaluate the variability associated with differences in velocity, as

well as evaluate the effects of recreational flow releases within velocity lanes.



ES 2.4.1. Macroinvertebrate Sampling

Samples were collected before and after each recreational flow release included in the study. A

Stanford-Hauer kicknet (Hauer and Resh 2006) was used to sample macroinvertebrates at each

location as described in Section 4.1.1 and Appendix A. Samples were preserved and analyzed

and subject to quality control checks by recognized macroinvertebrate laboratories.

ES 2.4.2. Periphyton Sampling

During 2008, periphyton samples were collected within each of the sampling strata, but were

taken from specific locations within the site that differed from those sampled for

macroinvertebrates in order to minimize interference effects of sampling disturbance that may

have occurred during benthic macroinvertebrate sampling. Both samples of filamentous algae

and diatoms were taken from suitable substrate elements located within the general area of

transects sampled for macroinvertebrates. Laboratory methods are discussed in Section 4 and

Appendix A.

ES 2.4.3. Seston Sampling

As described by Wallace et al. (2006), seston constitutes an important source of food for many

macroinvertebrates. Instantaneous seston concentrations (e.g., mg/L) can be easily measured by

filtering known volumes of water through glass-fiber filters. A detailed description of methods is

provided in Appendix A. Seston was characterized before and after each of the 2008 recreational

flow releases in both treatment and reference reaches. Three samples were taken, one in each of

three stream width segments across the river to account for non-uniform distribution of seston.

Seston samples were only obtained at the most downstream sampling habitat of each reach to

characterize seston concentrations for the reach. Laboratory methods are discussed in Section 4

and Appendix A.

ES 2.4.4. Physical Measurements

At the time of sampling, we measured water temperature, specific conductance, pH, and

dissolved oxygen using field instruments. Velocities also were measured within each reach



where benthic macroinvertebrate samples were taken, the physical habitat characteristics in the

California Bioassessment Worksheet; and a description and scoring of the physical/habitat

quality from the Physical Habitat Quality form was recorded to a data sheet for each site.

ES 2.5. Analytical Approach

Data resulting from the field studies and laboratory analyses were analyzed using several

statistical techniques including analysis of variance (ANOVA), t-Tests, and robust linear

analysis. The linear analysis was the primary analytical tool used (See Section 4 for a detailed

description of this approach). This approach allows us to combine effects across release flow

experiments to gain analytical power and to evaluate the relationship between the treatment and

reference reaches. It allows us to perform a broad range of tests and effect estimations to be

made with resulting confidence intervals. The advantage of using this approach is that we get

back not only the p-values, but also the effect estimates and measures of uncertainty on these.

Results were reported in tabular and graphic form (Section 5) including mean values, 95 percent

confidence intervals (CI), and probability values arising from statistical testing. In the results of

the linear analysis, the ratio of results from after-to-before (A/B) recreational flow releases are

used to assess the percentage change and the associated statistical probability is presented. For

2008 results the results are presented for both all of the velocity lanes combined and by

individual velocity lanes. This allowed us to better examine the effects of differences in

velocities on combined with the effects of before and after the recreational flow releases. These

are directly compared with the effects threshold identified a priori.

ES 3.0 ANALYSIS OF HYPOTHESES

In this section, we summarize the results of hypothesis testing. A full analysis of the hypotheses

is presented in Section 6. Herein, the summary focuses on the overall results and trends

associated with the test of each hypothesis. Discussions of the examination hypotheses by

velocity lane are only presented to the extent that they provide additional insight into the results.

Discussions that are more complete are presented in Section 6.



Each hypothesis is summarized in a tabular form in Table ES-1. For each hypothesis, the

hypothesis is stated, followed by a brief summary of results for each year, with the 2008 results

summary focusing principally on the results for all velocity lanes. For each hypothesis, the

sources of the results used from Sections 5.1 and 5.2 are presented. In addition, a tabulation of

results ratios by taxon (using the after-before density ratios, see below) is presented for each

hypothesis with the comments.

The results for each hypothesis include results for several taxa, which may display variability,

and even indicate opposing trends, in responses relative to recreational flow releases.

Hypotheses were tested using robust linear analysis and are represented by the ratio of the density

of the macroinvertebrate taxa in the Rock Creek reach After recreational flow release to the

density Before the recreational flow release (A/B ratio), which is compared to similar ratios for

macroinvertebrate densities in either or both the Cresta and UNF (depending on the appropriate

reference) reaches. The ratios from these comparisons are tabulated for each hypothesis to

indicate trends and variability, regardless of whether they met our ecological threshold for

adverse effect on ecological health. Where the results met the ecological threshold at a

statistically significant level, these results are specifically identified. The acceptance or rejection

of a hypothesis is based on the conservative statistical criteria established a priori (see Section

E2.3). In some cases, a hypothesis was rejected even though there were indications or trends that

the hypothesis may have been acceptable for one or more taxa relative to one of the reference

reaches, but similar trends frequently did not occur for all taxa relative to either or both reference

reaches, at the necessary level of statistical significance. Moreover, in some cases the lower

confidence interval of the resulting ratio does not preclude the potential for a decrease of 50

percent (our threshold for ecological significance), or the upper confidence interval did not

preclude an increase of a similar magnitude. These aspects of the results also should be

considered in interpreting the table below and in the Acceptance or Rejection of hypotheses.

The tabulated counts for each hypothesis are divided into categories representing: increase

(>1.2), little or no change (≥0.8--



Table ES-1. Summary of Hypotheses.

Hypothesis No. Hypothesis Statement Accepted (A) or Rejected (R)

Comments Source of Results

1

Attached filamentous algae will decrease

R

Overall, there is support for an increase in chlorophyll a from before to after in the Rock Creek reach (treatment reach). The support is strong for increases in photosynthetic biomass as evidenced by chlorophyll a in both the Rock Creek reach from before to after the recreational flow releases and in relation to the UNF (reference reach). The evidence is weak for the Cresta reach (reference reach), but there is no support for a potential decrease. Based on this, we reject the hypothesis of decrease. The tabulation of the results for the Rock Creek A/B ratio relative to the reference reaches used in interpreting this hypothesis is shown below. The results suggested increase rather than decrease, with one result increasing by more than 50 percent at a statistically significant level.

Statistically SignificantRatio >= 1.2 1.2>Ratio>=0.8 0.5< Ratio Ratio>=0.8 0.5< Ratio Ratio>=0.8 0.5< Ratio



Table ES-1. Summary of Hypotheses (continued).


Comments

5

Grazers will Decrease

R

In 2007, there was little change in grazer (also referred to as scrapers) density A/B ratios for Rock Creek relative to Cresta and UNF reaches. In neither reach was there a statistically significant difference. In 2008, there were increases in the Rock Creek A/B ratio compared to Cresta and UNF reaches, although not statistically significant. The hypothesis of decrease is rejected for all velocity lanes combined for 2007 and 2008. The tabulation of the results for the Rock Creek A/B ratio relative to the reference reaches used in interpreting this hypothesis is shown below. The results suggested increase or little change with no decrease. No result occurred at a statistically significant level.






Comments

7

Abundance of Benthic Macroinvertebrates that are Clingers will Remain Approximately Unchanged

A

For the clinger habit group, the result of the analyses suggested that clinger densities A/B ratios in the Rock Creek reach relative to the reference reaches tended to increase or remain similar between samples collected before the recreational flow releases compared to samples collected after the flows. The results relative to the reference reaches were not statistically significant. For the clinger habit group, the lower CI precludes the potential for a decrease of 50 percent, but does not preclude smaller decreases or increases. For individual taxa, there were both increases and decreases in the Rock Creek A/B ratio relative to the Cresta and UNF reaches, although none was statistically significant in 2007 or 2008. Based on the clinger habit group, the hypothesis of no decrease would be accepted for the Rock Creek A/B ratio relative to the Cresta and UNF reaches. The tabulation of the results for the Rock Creek A/B clinger ratio relative to the reference reaches used in interpreting this hypothesis is shown below. The results suggested a variety of results for the various taxa including increase, and little change. Results indicated no statistically significant change.

Statistically SignificantRatio >= 1.2 1.2>Ratio>=0.8 0.5< Ratio Ratio>=0.8 0.5< Ratio





Comments

8

Predators will remain approximately the same

A and R

Although this hypothesis indicated that no change would likely occur, both increases and decreases were found, some of which support and others of which do not support the potential of a decrease or increase in abundance of 50 percent. In 2007, the predator functional-feeding group A/B ratios for Rock Creek reach were slightly increased or remained similar at non-significant levels relative to the reference reaches. The CIs did not preclude increases or decreases. In 2008, there were decreases in predators relative to the reference reaches, with the decrease relative to the UNF reach being statistically significant and to below 50 percent. The CIs for predators in 2008, did not preclude decrease of more than 50 percent, but did preclude increases. The hypothesis is rejected for 2008 relative to the UNF reach, but not for the comparison with Cresta. There were increases, little change, and decreases among the taxa. The hypothesis is accepted in general, but there is one case for which the hypothesis would be rejected, with a statistically significant decrease in 2008. The tabulation of the results for the Rock Creek A/B predator ratio relative to the reference reaches used in interpreting this hypothesis is shown below. The results suggested a variety of results for the various taxa including increase, little change, and decrease. Results indicated a statistically significant decrease of 50 percent or more for predators in 2008.






Comments

9

Food will increase for macroinvertebrates that are in the filter-feeding functional-feeding group during a recreational flow release

R

The failure to see a systematic change in the seston levels could have resulted from the time interval that passed between collection of the Before-and-After seston samples, which followed the recreational flow by a few days to a week. The results do indicate, however, that any increases that may have occurred during recreational flows rapidly returned to “Before” recreational flow release concentrations following the return to pre-recreational release flows. These were then seen as “no change” in the “After” recreational flow release sampling. The small size larvae of the filter-feeder functional-feeding group sometimes experienced increased densities and other times decreased densities between recreational flow releases and across species. As with the small-sized larvae of the filter-feeder functional-feeding group, the larger sized larvae also experienced increased densities and other times little change. The hypothesis is not supported or weakly supported. The tabulation of the results for the Rock Creek A/B small size larvae ratio relative to the reference reaches used in interpreting this hypothesis is shown below. The results suggested a variety of results for the various taxa including increase, little change, and decrease. Results indicated a statistically significant decrease of 50 percent or more for one taxa, Chimarra in 2008.






Comments

9 alternate

However, the filter-feeding group may also be displaced during recreational flow releases, therefore, a decrease may occur.

R

For filter-feeders, the Rock Creek A/B ratios relative to the Cresta and UNF reaches suggested that there was little change or decrease. For these results, the hypothesis of decrease is not supported. Different patterns were found for the taxa of filter-feeders examined. Cheumatopsyche, Chimarra, and Hydropsyche tended to show a mixed pattern of increases, decreases, and unchanged population abundances, whereas Simulium (black flies) tended to show increases. However, among these groups the high variability of the densities does not preclude that potential for a 50 percent decrease (or increase) in abundance for several taxa. Cheumatopsyche, Chimarra, and Hydropsyche caddisflies tend to be displaced downstream when hydraulic shear stresses are very high in or near the thalweg during high flows. These larvae are sometimes able to colonize new areas and rebuild their capture nets. At other times, these larvae perish or are eaten by drift-feeding predators, particularly fish. Simulium, however, secrete a silk thread from their salivary glands that they use to maintain their positions during floods (periods of increased flow). There were no statistically significant decreases to support this hypothesis. The tabulation of the results for the Rock Creek A/B filter-feeder ratio relative to the reference reaches used in interpreting this hypothesis is shown below. The results suggested increases and little change. Results indicated no statistically significant change.






Comments

10

Increased food for deposit feeders will result in their increased growth.

A or R, by

individual taxon

The small-size (see description in methods) larvae of the mayflies Acentrella and Baetis tricaudatus, and the midge larvae in the family Chironomidae consistently showed an increase or no change in their A/B ratios, indicating that their abundance was not negatively affected during the recreational flow releases. Similarly, the crane fly larva Antocha showed increase or little change in A/B ratios. For cases with the above taxa, the upper CI did not preclude an increase in abundance. In contrast, the mayflies Camelobaetidius and Serratella, and the caddisfly Psychomyia, showed instances of decreases in these ratios, some of which were statistically significant and the CIs varied in support of no change, increases, or decreases. The large-size larvae of the mayfly Acentrella showed a different pattern than that found for the small-sized larvae, with a pattern of an increase in 2007 and decrease in 2008 in the A/B ratios, and the upper CIs do not preclude increases, except relative to the UNF reach in 2008. As with the small size larvae of Baetis tricaudatus and the midge larvae (Chironomidae), these groups consistently showed an increase or no change in their A/B ratios. This indicates that their abundance was not negatively affected by the recreational flow releases. The crane fly larva Antocha showed small decreases in 2007 and little change in A/B ratios in 2008. However, in many cases for the above taxa, the upper CI did not preclude an increase in abundance. In contrast, the mayfly Serratella and the caddisfly Psychomyia showed a tendency for decreases in these ratios, indicating that the larvae of these species were more susceptible to increased flows of the recreational releases than either Baetis or midges. In 2007, there was a statistically significant decreases of more than 50 percent for the Rock Creek A/B ratios of large Serratella relative to the UNF reach. In 2008, there was a statistically significant decrease of Acentrella with a decrease to 51 percent. For these cases, the null hypothesis is rejected. The tabulation of the results for the Rock Creek small size larvae A/B ratios relative to the reference reaches used in interpreting this hypothesis is shown below. The results suggested a variety of results for the various taxa including increase, little change, and decrease. Results indicated statistically significant decreases of 50 percent or more, in both 2007 and 2008.






Comments

11

Mean individual size will decrease for easily disturbed species

A and R, by

individual taxon

For the smaller size classes, in 2007, there were statistically significant decreases in Camelobaetidius relative to the Cresta reach and Chimarra relative to UNF. In 2008, the caddisfly Leucotrichia pictipes showed a statistically significant increase relative to the Cresta reach. Other taxa generally showed little change, a mix of responses or an increase. However, the lower CI in most of these taxa does not preclude the potential for a decrease of 50 percent, nor do the upper CIs preclude an increase of 50 percent. For the larger size classes, there was no statistically significant decrease. The caddisfly Leucotrichia pictipes showed a decrease relative to the Cresta reach, for which there was a statistically significant increase in small individuals. This suggested that the hypothesis might be correct for this taxon, but it is only a suggestion since it does not meet our threshold for decrease of large individuals. Other taxa showed little change or both increases and decreases. In most cases, the CIs did not preclude 50 percent decreases or increases and added uncertainty to conclusions that could be reached. The tabulation of the results for the Rock Creek A/B small size larvae ratio relative to the reference reaches used in interpreting this hypothesis is shown below. The results suggested a variety of results for the various taxa including increase, little change, and decrease. Results indicated a statistically significant increase of 50 percent or more in 2008 and decreases for two taxa of 50 percent or more in 2007.






Comments

12

Total macroinvertebrate biomass will show a short-term decrease.

R

Results consistently showed increases or no overall change in biomass, although no result was statistically significant. A decrease was observed for large macroinvertebrates in 2007 relative to the Cresta reach. However, a decrease of 50 percent is not precluded by the lower CI for some comparisons. The tabulation of the results for the Rock Creek A/B short-term biomass ratio relative to the reference reaches used in interpreting this hypothesis is shown below. The results suggested increase or little change for total and small biomass and, for large macroinvertebrate short term biomass there was a decrease, as well. Results indicated no statistically significant change.






Comments

13

Total macroinvertebrate biomass will show a long-term increase.

A

The long-term trend in biomass generally indicates an increase over time. Increased Rock Creek A/B ratio for total biomass increased relative to both reference reaches and was statistically significant relative to the Cresta reach. There was little change for large macroinvertebrate biomass relative to the reference reaches, and there were statistically significant increases in small macroinvertebrate biomass relative to both reference reaches. For 2008, there were increases in Rock Creek A/B ratios for long-term total macroinvertebrate biomass relative to the reference reaches, but neither was statistically significant. For the large macroinvertebrate biomass, there were decreases relative to the reference reaches, and the decrease relative to the UNF reach was statistically significant and of more than 50 percent decrease. Small macroinvertebrate biomass increased relative to the reference reaches, but neither increase was statistically significant. The tabulation of the results for the Rock Creek A/B long-term biomass ratio relative to the reference reaches used in interpreting this hypothesis is shown below. The results suggested increases for total biomass and small size macroinvertebrate biomass. For both of these categories there were one or more statistically significant increases of 50 percent or more. For large size macroinvertebrate long term biomass there was a combination of results including little change and decrease. Results indicated a statistically significant decrease of 50 percent or more in 2008.




meet the ecological threshold. These results are included in the overall ratio counts presented, as

well.

It should be noted that results that do not meet the ecological threshold are indicators of the

variety of outcomes. However, they cannot be used for the interpretation of the hypothesis given

the variable nature of the trends indicated in many cases, and the a priori ecological threshold

that needs to be met.

ES 4.0 ECOSYSTEM AND FAUNAL RESPONSES

We observed high variation in the macroinvertebrate communities, algal biomass and chlorophyll

a, and similar seston AFDM between sites and within each reach between the measurements

taken before and after recreational flow releases. Although the background variation among all

taxa examined in this study was high in all three reaches, in examining patterns across all

macroinvertebrate taxa, if we had observed a decrease in the Rock Creek reach densities, but

increased or stable densities of macroinvertebrates in the Cresta or UNF treatment reaches, this

would have indicated that major ecosystem alteration had occurred. However, this pattern did

not occur. Instead, we noticed that some taxa decreased, others increased, and others remained

nearly the same relative to the appropriate reference reaches. However, and perhaps our most

important finding of the effects of recreational flow releases, was that among some taxa we

found that the After (release) to Before (release) ratios showed an increase in the Rock Creek

reach that was lower than those that occurred in the reference reaches. This pattern suggests that

for these taxa, while not decreasing from before to after the recreational flow releases, still may

have been adversely influenced relative to the reference reaches.

Thus, in overview, we can conclude that the functioning of the entire riverine ecosystem, as

measured by the macroinvertebrate densities and growth, the increase in AFDM of the

periphyton, and based on our threshold criteria, was not adversely altered by the recreational flow

releases. However, changes did occur in the fauna following recreational flow releases.

We observed natural variation in macroinvertebrate densities between and within both the

treatment and reference reaches. Analysis of heterogeneity indicated that there were more



statistically significant increases in variance after the releases in Rock Creek then in Cresta.

There were relatively fewer differences between statistically significant changes in variances in

Rock Creek versus the UNF reach. In addition, and perhaps not unexpectedly, the response of

the benthic macroinvertebrate fauna includes a high degree of variation in time, and in addition,

possibly variability in the response to flows. Thus, some taxa appear to be affected and others

not affected by the releases. Of course, as mentioned above, the high variability prevents

definitive, generic answers about both of these responses in many cases. As a result, the results

of the Hypotheses tested were often equivocal, not just among the fauna examined but also with

contradictory patterns found between study years and across the months associated with the

recreational flow releases. Again, as mentioned above, we modified or added to the protocols of

the study in 2008 from those applied in 2007 to manage study risk and enhance the probability of

finding more definitive answers. These stratification tools did enhance our analysis capacity to

isolate effects across the suite of hypotheses.

The lane velocity stratified approach of 2008 likely emphasized greater differentiation of focused

effects in results found for specific Functional-Feeding Groups or specific Habit Groups (e.g.,

clingers vs. swimmers). Differences between years could also be driven by external forces. For

example, in 2008 there were wildfires in the vicinity of the study reaches during July and August.

Various studies have shown that ash and smoke from wildfires have potential to affect water

quality. Nitrate and ammonia in particular are associated with smoke gases that are rapidly

incorporated into streams, rapidly stimulating and increasing algal production, especially

instream environments that have riffle habitats and a significant degree of mixing (Spencer and

Hauer 1991). Ammonium ions in particular are known to be highly toxic to aquatic fauna.

While it is only speculative that this may have played a role in the declining macroinvertebrate

densities observed in 2008 across all three reaches, it does illustrate how outside events can

influence even the most closely controlled of field experimental studies. We emphasize that

differences between years do not negate one year’s results in favor of another, but rather provides

some possible explanation that interannual differences would be expected.



The results of this study found that responses of macroinvertebrates and periphyton to

recreational flow releases would not result in alterations that would be reflected in ecosystem-

wide responses.

Final Recreational Release Flow Macroinvertebrate Study Report 1 December 2011


1.0 INTRODUCTION

The 2001 license for Pacific Gas and Electric Company's (PG&E) Rock Creek-Cresta

Hydroelectric Project, FERC Project No. 1962 (Project), contains License Condition 17, which is

entitled “Recreation and Pulse Flow Biological Evaluation”. This condition required PG&E to

develop a Flow Evaluation Plan in consultation with the Rock Creek-Cresta Ecological Resource

Committee (ERC) and the United States Department of Agriculture-Forest Service (FS) within

one year of License issuance. The intent of the original study plan was to make an interim

evaluation of the data collected under the plan, after three years, to determine if the recreational

flow releases have either a beneficial, neutral, or no significant adverse effect on the aquatic

biota, as determined by the ERC and FS2. One component of the Flow Evaluation Plan is to

determine the effects of the recreation flow releases on the macroinvertebrate community. In the

original study conducted, the ERC and FS could not determine any conclusive effects (beneficial,

neutral, or no significant adverse) of recreation flow releases on macroinvertebrates. This project

is the result of that effort.

The current report (Study) has been developed in consultation with macroinvertebrate and

aquatic ecology experts under the guidelines of the Project License Condition 17 and the Project

Settlement Agreement with the intent to collect macroinvertebrate and related biological (e.g.,

periphyton, seston), habitat, and physicochemical data in recreation flow release-affected reaches

as well as in reference reaches in a manner appropriate to address the hypotheses developed in

the study plan approved by the ERC and FS (Resh et al. 2007, 2008).

1.1 SETTLEMENT AGREEMENT

As part of the Rock Creek-Cresta relicensing, PG&E entered into a Settlement Agreement with

14 other parties to establish a collaborative process to resolve among all parties streamflow

2 The specific language from the license, page 52 of the appendix reads, “If, after 3 years of data collection and assessment, either beneficial, neutral, or no significant adverse effects (as determined by the ERC and Forest Service) are observed, recreation flow releases days will be added as supported by on-water recreational use monitoring in Paragraph E, Condition 16. Days will be adjusted after that period as supported by ecological and on-water recreational use monitoring.”



issues for ecological purposes, river-based recreational use, and other Resolved Subjects in

support of FS’s Final 4(e) Conditions and FERC conditions under a new Project license. The

Settlement Agreement, along with the License, addresses the biological evaluation of recreation

and flow releases with the goal of the ERC and FS to identify effects of the recreational flow

releases, and whether those effects are beneficial, neutral, or significantly adverse on the aquatic

biota (including macroinvertebrates).

1.2 PREVIOUS STUDIES

1.2.1 Recreation Flow Specific Studies

As a condition of the new license and the Rock Creek-Cresta Relicensing Settlement Agreement

(PG&E 2000), PG&E is required to provide recreation flow releases ranging from 800 to 1,600

cfs in all water-year types. These flows are currently supposed to be provided on a monthly basis

from late June through late October during the typical low-flow (i.e., base flow) season. Specific

studies designed to evaluate the effects of these flows on amphibians, fish, and

macroinvertebrates in this portion of the North Fork Feather River (NFFR) are described in the

Rock Creek-Cresta Relicensing Recreation and Pulse Flow Biological Evaluation Study Plan

(PG&E 2002a). PG&E led studies for the macroinvertebrate portion of these biological

evaluations over a three-year period beginning in 2002 and continued for two additional years

(GANDA 2002, 2003, and 2004).

The first year of the studies focused on monitoring macroinvertebrate drift (i.e. the phenomenon

in which normally benthic-dwelling organisms enter the water column and are dispersed

downstream) before, during, and after recreational flow events. The original study hypothesis, as

defined in the Study Plan (PG&E 2002a), was that the release of recreation and controlled spring

flow releases would not displace typically non-drifting organisms at a higher than base rate. In

the context of biological evaluations of recreational streamflow releases in the NFFR,

documentation of the extent of disturbance using quantitative measures, and demonstration of

impacts to downstream biota (if any), are critical for decision-making. Drift data were collected

in 2002. The results from the 2002 studies, guidance from peer reviewers, and discussions

between PG&E and the ERC and FS, lead to a shift of the focus of macroinvertebrate evaluations



during 2003 (the second year of this study) from drift sampling to evaluation using benthic

artificial substrate (rock basket) sampling. The shift in focus attempted to relate observations

from the 2002 drift study to potential direct impacts on the benthic macroinvertebrate source

community. The study’s null hypothesis driving benthic-macroinvertebrate evaluations was that

recreational flow releases would not produce appreciable differences in post-recreational flow

release benthic macroinvertebrate communities compared to those found in pre-recreational flow

release conditions. Benthic sampling was repeated in 2004 (the third year of this study)

following the same methodology and study design agreed upon for 2003 and the results were

reported to the ERC and FS. These studies included GANDA 2002, 2003, and 2004. However,

results were deemed inconclusive.

1.2.2 California Stream Bioassessment Procedure (CSBP) Studies

As part of the License compliance monitoring efforts for the Project, benthic macroinvertebrate

sampling has been conducted in the Feather River since 1999. Benthic samples collected from

regulated Project reaches of the NFFR, as well as other partially regulated and unregulated

reaches of the NFFR, EBNFFR, and Middle Fork Feather River (MFFR) during

September/October of each year sampled (1999-2002 and 2004-2006) followed the CSBP (the

method recommended by California Department of Fish and Game [CDFG 2003] at the time

those studies were performed). This rapid bioassessment technique was developed by CDFG)

based on prior work by US EPA and was the statewide standard for macroinvertebrate

bioassessments. Characterizations of the metrics derived from benthic macroinvertebrate (BMI)

samples in these reaches of the Feather River were used as indicators of disturbance and habitat

quality in these reaches in the design of this present study.

1.3 GOALS AND OBJECTIVES

1.3.1 Study Goals and Objectives

The objective of this current study is to determine the nature and potential beneficial, neutral, and

significant adverse effects of the Project recreational flow releases on the macroinvertebrate

community and primary producers that may relate to the goals established in the Rock-Creek



Cresta Settlement Agreement. This Study is primarily based on testing specific hypotheses using

key macroinvertebrate taxa, functional-feeding groups, habitat use groups, food sources, and

primary producers to identify whether beneficial, neutral, or significant adverse effects are the

result of recreational flow releases. The hypotheses are stated in a formal statistically testable

structure, and statistical and ecological effect thresholds are established for significance.

The goal of this Study is to provide sufficient data through a carefully designed study to relate the

effects of recreational flow releases on the macroinvertebrate community and primary producers.

The resulting information should assist the ERC and FS with the management of recreational

flow releases and evaluation of the beneficial, neutral, and adverse effects that would result to the

benthic macroinvertebrates and primary producers.

2.0 PROJECT DESCRIPTION

The Project includes the Rock Creek and Cresta Developments (Figure 2-1). The Rock Creek-

Cresta Project was built between 1948 and 1950 and began operation in 1950. Major

developments in the NFFR began with the construction of Canyon Dam in 1914 and the

expansion of Lake Almanor in 1916 and 1927. Butt Valley Reservoir was constructed to

generate power using Lake Almanor storage and was completed in 1924 and discharges to the

NFFR through the Caribou 1 and 2 powerhouses. In 1958, Belden Forebay was constructed

downstream of the Caribou powerhouses and provides flow to the Belden Powerhouse located

downstream on Yellow Creek. Instream flows are released to the NFFR from Belden Dam,

currently through the Oak Flat Powerhouse, which was completed in 1985.

The Rock Creek development is located downstream of Yellow Creek. The Rock Creek

development, which is the upstream development, consists of: the Rock Creek reservoir with a

gross storage capacity of 4,400 acre-feet and a surface area of 118 acres; a 126-foot-high, 567-

foot-long dam; an intake structure within the reservoir about 100 feet upstream of the dam; a

tunnel approximately 6.5 miles long; two penstocks, 906 and 938 feet long, respectively; and a

powerhouse containing two turbine-generator units with a total installed capacity of 114,000

kilowatts (kW). There is an 8.4-mile-long bypassed reach between the reservoir and

powerhouse.



Figure 2-1. North Fork Feather River from Lake Almanor to Lake Oroville, California.



The Cresta development is the next reservoir-forebay development downstream of the Rock

Creek development (Figure 2-1). It consists of: the Cresta reservoir with a gross storage capacity

of 4,140 acre-feet and a surface area of 95 acres; a 114-foot-high, 378-foot-long dam; an intake

structure within the reservoir about 100 feet upstream of the dam; a tunnel almost four miles

long; two penstocks, 800 and 775 feet long, respectively; a powerhouse containing two turbine-

generator units with a total installed capacity of 71,000 kW; and a 52-foot-long tailrace. There is

a 4.9-mile-long bypassed reach between the reservoir and powerhouse.

The primary storage reservoir on the NFFR is Project No. 2105 Lake Almanor, located about 20

miles upstream of the Rock Creek development. Water released from Project 2105's Belden

reservoir and powerhouse, along with the natural flow of the EBNFFR and small tributaries,

flows into the Rock Creek reservoir where it is diverted through a tunnel to two parallel

penstocks that serve the Rock Creek powerhouse. Water released from the Bucks Creek Project

powerhouse enters the NFFR about one mile above the Rock Creek powerhouse.

The combined flow from Rock Creek and Bucks Creek facilities, along with the flow from

several small tributaries along the NFFR, enters the Cresta reservoir. Water is diverted through a

tunnel to two parallel penstocks that serve the Cresta powerhouse. Water released from this

powerhouse enters the Poe Project's reservoir, which begins immediately downstream of the

Cresta powerhouse.

3.0 APPROACH

3.1 GENERAL APPROACH

Our approach in evaluating the effects of recreational flow releases in the NFFR on

macroinvertebrates is to focus on highly specific questions based on accepted theory and

empirical observations about macroinvertebrate and river ecology. The questions selected are

those that can be posed as testable hypotheses and measured using recognized techniques and

quantifiable measures. These questions address effects on frequency of occurrence and density

of abundant macroinvertebrate taxa, effects on abundance of taxa recommended by local anglers

as dominant fish-food organisms, effects on the population and size structure of the abundant fish


Rock Cr

ROCK CREEK - CRESTA RECREATIONAL RELEASE FLOW...

Documents

Transcript of ROCK CREEK - CRESTA RECREATIONAL RELEASE FLOW...