Efficiency of fecal coliform, phosphorous and suspended solids removal in suburban storm water wetlands, Arcata, California

The City of Arcata, California has identified bacteria, nutrients and suspended solids as pollutants of concern in the city's waterways. Suburban areas are known sources of fecal contamination, nutrients and suspended solids. Suburban areas increase the amount of impervious surfaces in watersheds causing peak flow and volume of storm water runoff to significantly increase. As runoff and overland flow increase so does the ability of water to entrain and carry a higher pollutant load. Wetlands have been increasingly used and found effective in reducing many of the water quality concerns associated with suburban runoff. Arcata has four wetlands located on three streams receiving suburban storm water through storm water infrastructure. Two of the wetlands are depressional and two are free water surface. Each stream was sampled during the 2010-­‐2011 hydrologic year upstream and downstream of the wetlands during both storm and base flow events to determine reduction of total suspended solids (TSS), organic suspended solids (OSS), inorganic suspended solids (ISS), fecal coliforms, turbidity, and phosphorous. Of the metrics tested only suspended solids showed significant reductions. The highest mean TSS, ISS, OSS and fecal coliform concentrations came from Campbell Creek, which had the highest percent impervious surfaces (23%) comprised primarily of suburban housing. Suspended solids were about 22% organic by weight during storm and base flows making organic matter a significant portion of the suspended load.