Contra Costa Monitoring and Assessment Program Preliminary Assessment of Aquatic Life Use Condition in Contra Costa Creeks Summary of Benthic Macroinvertebrate Bioassessment Results (2001-2006) Prepared for: Contra Costa Clean Water Program 255 Glacier Drive Martinez, CA 94543 Prepared by: Eisenberg, Olivieri and Associates, Inc. (EOA) 1410 Jackson St. Oakland, CA 94612 June 22, 2007 Preface and Acknowledgements Please note that assessments described, and conclusions presented in this report should be considered preliminary and non-regulatory in nature. Results are based on limited data analyses and may be revised in the future as new analytical tools are developed. Additionally, many volunteers, agency staff and consultants assisted the Contra Costa Clean Water Program in collecting bioassessment data described in this report. In particular, volunteers from the Friends of Pinole, Alhambra, Marsh, Kirker and Mt. Diablo Creek Watersheds, Friends of Five Creeks, and the San Pablo Creek Watershed Awareness Network, as well numerous other volunteers have put in countless hours in the field. Additionally, the Program’s Watershed Assessment and Monitoring (WAM) Subcommittee members have provided guidance to Program staff, and Scott Cressey (Cressey and Associates) has provided assistance to the Program throughout the implementation of the Contra Costa Monitoring and Assessment Program (CCMAP). Executive Summary Stormwater monitoring programs use a variety of indicators to assess the physical, chemical and biological integrity (i.e., condition) of water bodies, including conventional water quality measurements (e.g., dissolved oxygen and pH), sediment and water chemistry (e.g., heavy metal concentrations) and toxicity (e.g., bioassays) testing, channel geomorphology measurements and biological assessments (e.g., bioassessments). In 2001, the Contra Costa Clean Water Program selected fresh water benthic macroinvertebrate (BMI) communities as their lead indicator of aquatic life use condition in Contra Costa water bodies. Additionally, volunteer monitors began to conduct bioassessments using BMIs in 2005. BMIs are composed primarily of insect larvae, mollusks, and worms and they are an essential link in the aquatic food web, providing food for fish and consuming algae and aquatic vegetation. These organisms are also sensitive to disturbances in water and sediment chemistry, and physical habitat, both in the stream channel and along the riparian zone. From 2001 to 2006 the Program and volunteers conducted bioassessments at 120 sampling stations in creeks within 16 of the 30 major watersheds in Contra Costa County using the California Stream Bioassessment Protocol developed by the California Department of Fish and Game. To provide an initial measurement of Aquatic Life Use condition at these stations, a preliminary Benthic Index of Biotic Integrity (B-IBI) for creeks in Contra Costa County was calculated using information gained from the development of similar indices for creeks in Southern and Northern California regions. Ranges of B-IBI scores were then assigned to poor, marginal, fair, good and very good categories. Preliminary results suggest that roughly 40% of creek stations sampled in Contra Costa County score in the very good, good or fair categories. Stations draining open space and East Bay Regional Park District (EBRPD) land located in Upper Marsh Creek watershed and open space areas in the Kellogg Creek watershed scored the highest of all stations sampled. Additionally, individual stations in upper Las Trampas Creek, Mitchell Creek (Mt. Diablo Creek watershed), Franklin Creek (Alhambra Creek watershed), and North Fork Rodeo Creek had relatively high preliminary B-IBI scores. The lowest B-IBI scores were calculated for stations in East Antioch, Grayson and Kirker Creek watersheds. Annual variability in B-IBI scores at stations sampled in three or more years is moderate to low, indicating that the ability for the Program to detect significant changes (positive and negative) in aquatic life use conditions over a relatively short period of time (<10 years) may be possible. Additionally, volunteer citizen monitors have provided and continue to provide valuable information regarding the condition of aquatic life uses in Contra Costa creeks, and the Program should consider continuing to provide support for volunteers in the future. Table of Contents 1.0 INTRODUCTION ................................................................................................................................................ 1 1.1 OVERVIEW OF MONITORING PROGRAMS .............................................................................................................. 1 1.1.1 Contra Costa Monitoring and Assessment Program ........................................................................ 1 1.1.2 Contra Costa Volunteer Creek Monitoring Program ...................................................................... 2 1.2 BENTHIC MACROINVERTEBRATES AS INDICATORS OF AQUATIC LIFE USE CONDITION .............................................. 2 2.0 CONTRA COSTA CREEKS AND BIOASSESSMENT METHODS .................................................................... 4 2.1 CONTRA COSTA WATERSHEDS AND SAMPLING STATIONS ..................................................................................... 4 2.2 BIOASSESSMENT METHODS ................................................................................................................................. 5 2.2.1 Field Procedures .................................................................................................................................... 5 2.2.2 Laboratory Procedures ......................................................................................................................... 5 2.3 PHYSICAL HABITAT ASSESSMENT METHODS ....................................................................................................... 13 2.4 DATA QUALITY ASSESSMENT ............................................................................................................................ 13 2.5 ANALYSIS AND INTERPRETATION METHODS ....................................................................................................... 13 2.5.1 Benthic Macroinvertebrate Metrics ................................................................................................. 13 2.5.2 Benthic Indices of Biotic Integrity ................................................................................................... 13 3.0 RESULTS .......................................................................................................................................................... 17 3.1 COUNTY-WIDE OVERVIEW ................................................................................................................................ 17 3.1.1 Most Dominant Taxa............................................................................................................................ 17 3.1.2 Functional Feed Groups (FFGs) ......................................................................................................... 17 3.2 CONDITION OF AQUATIC LIFE USES IN CONTRA COSTA CREEKS ........................................................................... 18 3.3 ANNUAL VARIABILITY IN B-IBI SCORES ............................................................................................................. 23 3.4 POTENTIAL FACTORS AFFECTING AQUATIC LIFE USES ....................................................................................... 24 3.4.1 Urbanization ......................................................................................................................................... 24 3.4.2 Reach-Scale Physical Habitat Quality ............................................................................................. 25 3.5 WATERSHED SPECIFIC OBSERVATIONS .............................................................................................................. 26 3.5.1 Alhambra Creek Watershed ............................................................................................................... 26 3.5.2 Pinole Creek Watershed ..................................................................................................................... 26 3.5.3 Wildcat Creek Watershed .................................................................................................................. 26 3.5.4 San Pablo Creek Watershed ............................................................................................................... 26 3.5.5 Mt. Diablo Creek Watershed ............................................................................................................. 26 3.5.6 Marsh Creek Watershed ..................................................................................................................... 26 3.5.8 Kellogg Creek Watershed ................................................................................................................... 27 3.5.9 Baxter and Cerrito Creek Watersheds ............................................................................................ 27 3.5.10 Las Trampas Creek Watershed ..................................................................................................... 27 3.5.11 Grayson Creek Watershed ............................................................................................................. 27 3.5.12 East and West Antioch Creek Watersheds ................................................................................