An Evaluation of Presence and Source of Fecal Contamination at Golden Gardens Park

摘要

Golden Gardens is an 87.8 acre Park in Seattle, WA that has come under recent scrutiny over concerns about water quality in the streams and at the beach. Located just north of Shillshole marina in Seattle it has a swimming beach which is 1439 m in length, as well as a forested region directly east of the beach on a relatively steep hill with several drainages flowing into the sound. The purpose of this study was to assess the levels of indicator bacteria in beach water and in the fresh water drainages and to determine if the bacterial contamination is related to human or animal inputs. Specifically, we were interested in determining if the off-leash area for dogs, located on the hill above the beach, was contributing to the contamination. Water was collected five times from June-August 2010 at 4 locations at two depths along the beach and as many as 20 locations in the drainages on the hill. One-hundred ml aliquots of water were analyzed in duplicate for each site sampled via membrane filtration for fecal coliforms, and enterococci. DNA from Enterococci isolates were amplified by PCR targeting the esp gene in enterococci and DNA extracted from 200ml of fresh water was amplified for the 16S rRNA gene in Bacteroides to determine the source of contamination. Fecal coliform levels for marine beach water at Golden Gardens typically meet WA State bacteriological criteria for secondary contact recreation. The stream water frequently exceeded the USEPA recommended level of 33 enteroccoci per 100ml. Preliminary PCR results showed that two of 24 samples from one sampling period were positive for human specific Enterococcus. PCR analysis for human specific Enterococcus and for human and canine specific Bacteroides is still underway for the other sampling periods