Occurrence and Fate of Escherichia Coli from Non-Point Sources in Cedar Creek Watershed, Texas

Fecal contamination is the pollution caused by the microorganisms residing in the intestine of warm blooded animals and humans. Bacteria are the prime cause of contamination of surface waters in the US. The transport of microorganisms into waterways can have detrimental effects on water quality and human health especially if the pathogenic strains are ingested. E. coli is used as an indicator of fecal contamination. Detection of these bacteria in a water body above set limits poses a potential health hazard. Various sources contribute to the bacterial contamination of a water body. The sources need to be identified and quantified for their E. coli content to measure bacteria loads in the waterbody accurately. In many cases, in-situ re-growth is also believed to be a considerable source of E. coli. Also re-growth of E. coli in landscapes due to favorable environmental conditions (e.g., rainfall after dry weather conditions) is one of the major phenomena affecting E. coli concentration in streams. Thus the environmental factors like temperature and soil moisture that influence transport, persistence, re-growth, and survival of E. coli in landscapes were studied. The objective of this study was to identify, characterize and quantify E. coli loads from feces of four different animals and monitor survival, growth and re-growth at four different temperatures and moisture contents over a period of seven days. Findings of this research will aid in Watershed Protection Plan (WPP) development and Total Maximum Daily Load (TMDL) development to address impairment from point and non-point source pollution of E. coli. Wildlife and range cattle manure samples responsible for fecal contamination of Cedar Creek were identified and four fecal sources out of those were quantified for the E. coli concentrations. No significant difference was found upon comparing the E. coli concentration for each species between the genders. Sub-adult cattle demonstrated significantly higher E. coli concentrations than adult cattle. Growth and die-off rates were measured at different temperatures (0degreesC, 10degreesC, 25degreesC, and 50degreesC) and moisture conditions (1%, 25% 56.5% and 83%). E. coli concentrations in cattle and raccoons feces showed highest survivability and growth at 20degreesC out of all the temperatures studied. There was no survival of E. coli from either species at 50degreesC after 24 h. E. coli in cattle and raccoons samples exhibited greater growth at lower, nearly aerobic soil moisture content (25%) for all days compared to nearly anaerobic soil moisture content (83%).