Status and trends of fecal indicator bacteria in two urban watersheds.

This paper examines bacterial levels and their causes in two Houston bayous (Texas). Buffalo and Whiteoak bayous are two of the most contaminated water bodies in Texas for indicator bacteria, based on the frequency and magnitude of contact recreation water quality exceedances. Examination of historical data indicates frequent exceedances, although some improvement has been made since the 1970s. Statistical analyses showed some correlation between in-stream fecal coliform concentrations and rainfall and with land use. Differences in fecal coliform concentrations were found between high- and low-flow conditions in Whiteoak Bayou, while reservoir releases confounded this relationship in Buffalo Bayou. Wastewater treatment plant effluent was found to make up two-thirds to three-fourths of the median flow in both bayous. Effluent sampling was conducted at 72 of the approximately 140 wastewater treatment plants (WWTPs) in the watersheds, providing evidence that WWTP effluent could act to maintain low-flow concentrations of fecal coliform in the bayous.