Examination of Nutrient Sources and Transport in a Catchment with an Audubon Certified Golf Course

Abstract

Water bodies in the East Bay Regional Park District (EBRPD), California, United States, provide aesthetic value and critical ecosystem services, but are often adversely affected by the activities and infrastructure of the intensely urban environment that surrounds the parks. EBRPD leases a golf course (Tilden Golf Course (TGC)) in Tilden Regional Park, one of its most popular parks located in the Berkeley Hills, which was certified as an Audubon Cooperative Sanctuary in 2013. Nonetheless, application of nutrients and pesticides (fungicides, plant growth regulators and herbicides) are commonly used to maintain turf systems and may be transported via surface runoff or through subsurface drainage to surface waters, leading to the concern that golf courses are a major contributor to water pollution. We studied the possible contribution of nutrients (NO3-N and PO4-P) and pesticides transported via storm-generated surface runoff and via groundwater from TGC to the primary drainage in the watershed, Wildcat Creek. Lake Anza, a popular open water swimming lake, is located downstream from TGC and experiences occasional nutrient-driven algal blooms that have caused swim beach closures. Measured NO3-N and PO4-P in the stream, at times, exceeded concentration limits of 1 mg/L (as N) and 0.05 mg/L (as P), respectively, considered protective of aquatic ecosystems by the United States Environmental Protection Agency (1986). We found that phosphorous likely has a dominant natural source, but nitrogen is primarily derived from a golf course fertilizer source and its concentration increases in the stream during runoff events, while other soluble species decrease. Analyses of pesticides in water reveal the presence of Azoxystrobin in stream water at the golf course, but with concentrations well below the regulatory limit. These results indicate that all other pesticides applied on TGC are not likely transported to the stream, suggesting future reactive transport research must treat contaminant species independently based on their specific transport behaviors.