Nutrient and fecal coliform discharge from coastal North Carolina golf courses

Water quality investigations were conducted at five golf courses in southeastern North Carolina to determine levels of pollutants contributed by the courses to adjacent coastal streams. In general, nitrate levels were greater in streams leaving the courses compared with streams entering the courses, but concentrations varied considerably among courses. Ammonium concentrations increased in passage through most of the courses. Orthophosphate concentrations were elevated on midcourse sites on two courses, but were low in the outflow water except at one course. The golf courses studied were not significant sources of fecal coliform bacteria to nearby waterways; in fact, passage through some courses served to reduce coliform loads entering from upstream suburbs. Recent rainfall and fertilization application influenced outfall nitrate concentrations only at some courses. Landscape management practices appeared to play a critical role in determining nutrient concentrations in the outfall and at midcourse sites. Nutrient addition bioassay experiments conducted in one of the coastal creeks receiving golf course efflueut demonstrated that nutrient concentrations as low as 50 to 100 mu g nitrate N L-1 were capable of causing significant phytoplankton biomass increases. Nitrate levels in the outflow streams were at or above concentrations causing significant increases in phytoplankton biomass in our bioassay experiments. These coastal creeks host spring and summer algal blooms; thus, some golf course discharge nutrient concentrations are at levels great enough to contribute to eutrophication problems in estuarine waters. Vegetated buffer zones, wet detention ponds, and wooded wetland areas led to considerably lower nutrient output than sites lacking such management practices and should be used whenever possible to protect nutrient-sensitive receiving waters.