Bioassessment of Two Urban Creeks in the Presidio Bonnie Lee Environmental Sciences, University of California at Berkeley Abstract The first step in restoration of a creek is to establish a baseline in which to formulate future restoration management practices. As part of the restoration effort for the Tennessee Hollow Creek (THC ) at the Presidio, I conducted an initial characterization of the creek and the Fort Scott Creek (FSC) in the Presidio. I hypothesized that THC will be the poorer quality of the two creeks. Using Fort Scott Creek as a reference creek, I used the California Stream Bioassessment Protocol and archived US Army data to evaluate the quality of THC and FSC. By calculating the EPT index, taxon richness, tolerant taxon index, and percent dominant taxon, I found that 3 of the 4 metrics supported the hypothesis. EPT index and taxon richness were also plotted with total dissolved nickel and copper concentrations to see if metals in surface water would affect the macroinvertebrate community. EPT index was low in presence of metals but no noticeable differences were seen in taxon richness. Although FSC has been determined to be the more pristine creek, bioassessments must be continued so that dependable restoration goals may be set.Introduction Degradation of rivers and streams in the form of sedimentation, excess nutrients, or anthropogenic intervention, has been the focus of restoration efforts around the world (Nolan and Guthrie 1998, Schauman and Salisbury 1998). Urbanization in South Africa has caused the accumulation of pollutants in waters and is now using Best Management Practices to minimize the impacts to the environment (Braune and Wood 1999). River Mersey, an urban creek in the UK once known for its polluted waters and heavily engineered watercourses in Europe, have re-established fish populations in certain parts of the catch (Nolan, 1998). In the US, 642,881 of the 3.5 million miles of rivers and streams have been documented in the 1992 National Water Quality Inventory with studies showing that while 56% of this stream mileage have been determined suitable for multiple uses such as drinking water supply, fish and wildlife habitat, recreation, agriculture, and flood prevention and erosion control, the other 44% have been considered degraded (Karr and Chu 1999, US Department of Agriculture et al. 1998). Due to the poor quality of bodies of waters in the US, fish advisories have increased 26% in 1996. In California Rivers, there has been a 67% decline or disappearance in fish species since the 1850s (Karr and Chu 1999). As part of recent concerns to the continued degradation, efforts are being made to restore streams and the habitat around them. One example is the proposed restoration of Tennessee Hollow Creek (THC) in the Presidio, San Francisco by the National Park Service. The restoration effort for THC is currently in the first stages of planning, identifying the problem with the help of conducting experiments and analyzing data (Kern and Youngkin 1998). Chemical water analysis is a common way to assess water quality in streams, but dependence on this one method is often unreliable. Nationally, only 25% of the river miles were considered impaired based on chemical assessment whereas using biological methods, 50% of the river miles were categorized as impaired (Karr and Chu 1999). This discrepancy may be because chemical analysis presents only one aspect of habitat monitoring. Bioassessments offer an integrated approach in assessing aquatic ecosystems by evaluating relationships between organisms and their physical habitats with the help of biometrics. These biometrics, or measurements of biological attributes, such as taxon richness (the number of taxon present in a sample), percentage of most dominant taxon (the percent of the total number of organisms belonging to the same taxon), Ephemeroptera-Plecoptera-Trichoptera (EPT)richness (the number of individuals belonging to the EPT taxon), and organism density (the number of organisms in a known area) are just a few of the more reliable metrics (Poulton et al. 1995, Resh et al. 1995). Therefore, a biological approach or a bioassessment would more accurately assess the quality of an aquatic ecosystem. Due to the low cost of bioassessments compared to chemical analysis, there are 42 states using multimetric assessments of biological conditions. California’s Department of Fish and Game adapted an EPA protocol, the California Stream Bioassessment Procedure (CSBP) for use by citizen monitors (Karr and Chu 1999, California Department of Fish and Game 1998). Using this standard protocol, I conducted bioassessments of the two creeks in the Presidio, THC and Fort Scott Creek (FSC) to assess their aquatic habitat quality. Research Goal In order to restore THC, we must first determine the condition of the present aquatic habitat to base future restoration decisions. In this study, I have established an initial characterization of the aquatic habitat by conducting a bioassessment of the creek and the reference creek, Fort Scott Creek. Next, I calculated EPT index, taxon richness, percent dominant taxon, tolerant taxon index, and percent similarity to reference site. Using archival data, I studied the relationships between the EPT index and taxon richness with the total dissolved nickel and copper concentrations, two of the metals that are of concern in the surface waters of THC. I have tested the hypothesis that FSC will be the least degraded of the two creeks. Description of Study Sites Tennessee Hollow Creek (Fig.1) is part of the Tennessee Hollow Watershed, draining 111 hectares within the Marina Groundwater Basin within the Presidio of San Francisco (Kern and Youngkin 1998). The creek has three tributaries, all of which run through landfills. The western tributary flows year round except during the summer when the groundwater level drops. This tributary emerges from Landfill E, a fill site containing hazardous materials, construction debris, and petroleum waste. The central tributary flows through the 1940s Landfill 1, filled deep with building debris, asbestos wrapped ducts, and incinerated debris related to medical units, and Landfill 2, filled with 3.05m thick of building debris and household wastes (US Army Corps of Engineers 1991). The western and central tributaries merge and transect the eastern tributary, which flows through an unofficially designated fill hypothesized to
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