Water Quality of Peralta and Courtland Creek Oakland, CA

Allan Ahumada, Aminah Butler, Mellany Davis, Yarely Guzman, Micah Johnson, Xochitl Ponce, Kim Zhen

Beginning in the summer of 2012 and continuing to the present time our group has been assessing the water quality of Courtland Creek, which flows from Northeast to Southwest in East Oakland, California. During the summer of 2014 we began assessing the water quality at nearby Peralta Creek to compare the health of Courtland Creek with another one within the same watershed. In making our assessment we have analyzed samples collected from three different sites along both creeks for Nitrate, Phosphate, and Ammonia concentration levels. Additionally, we conducted benthic macroinvertebrate surveys at one site along each creek. Preliminary results indicate that nitrate levels in Courtland Creek waters are very high, which we believe is the result of human and animal waste entering into the creek. There were also unusually high levels of Phosphate and Ammonia detected in creek waters. Such high concentrations were noted in a past study and in an attempt to address this problem we initiated a native plant restoration project at one particular site located at the intersection of Courtland and Thompson avenues. This effort has resulted in a reduction in levels of Nitrate, Phosphate and Ammonia. The average levels of these compounds in waters collected near the restoration site were lower than those found in samples collected at other sites. However, they are still well above levels that are harmful to invertebrates and fish. Nitrate, Phosphate and Ammonia concentration levels in samples collected from Peralta Creek were significantly lower than those collected from Courtland Creek. For example, the maximum level of nitrate detected in Courtland Creek waters was 50 PPM while the maximum found in Peralta Creek waters was 15 PPM. We have concluded that the observed high levels of various compounds are the result of animal waste and human feces spilling directly into Courtland Creek. Results from a recent Environmental Protection Agency (EPA) – led E. coli survey that included this watershed support this claim.

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