Water Air Soil Pollut (2011) 215:525–547 DOI 10.1007/s11270-010-0497-7
Development of Regression-Based Models to Predict Fecal Bacteria Numbers at Select Sites within the Illinois River Watershed, Arkansas and Oklahoma, USA Morgan M. David & Brian E. Haggard
Received: 16 October 2009 / Accepted: 28 May 2010 / Published online: 12 June 2010 # Springer Science+Business Media B.V. 2010
Abstract The Illinois River Watershed is a multifacet basin with ecological and economic importance to its local stakeholders in northwest Arkansas and northeast Oklahoma, USA. The numbers, transport and sources of fecal bacteria in streams was identified as a research priority of the USDA NRI Water and Watershed Program in 2006, and the objective of this study was to evaluate the relation between fecal bacteria and other measured physicochemical parameters in water samples collected from selected sites throughout the Illinois River Watershed. An existing database (i.e., National Water Information Systems, NWIS) from the US Geological Survey (USGS) was used in this project. The data obtained includes discharge, pH, temperature, dissolved oxygen, Escherichia coli (E. coli), fecal coliform, and fecal streptococci among several other physic-chemical parameters. A synthetic model, based on multiregression analysis, was developed to predict fecal bacteria numbers at these selected sites based on
M. M. David Environmental Engineering Program, Department of Biological and Agricultural Engineering, University of Arkansas, Fayetteville, AR, USA B. E. Haggard (*) Arkansas Water Resources Center, University of Arkansas, 203 Engineering Hall, Fayetteville, AR 72701, USA e-mail:
[email protected]
available USGS NWIS data, and the multiple regressions were significant at almost every site for all three bacteria groups. However, the physicochemical parameters used in the equations were very different across sites and fecal bacteria groups, suggesting that the development of such predictive models is site and bacteria group specific even within one watershed. Keywords Fecal coliform . E. coli . Fecal strep . Regression models
1 Introduction Fecal bacteria are commonly used as indicators of water quality relative to designated beneficial uses particularly drinking water supply and contact recreation. Fecal indicator bacteria concentrations typically range from less than 100 colony forming units (CFU) 100 mL−1 in pristine waters and surpass 1,000 CFU 100 mL−1 in impaired systems (Niemi and Niemi 1991). These micro-organisms originate from animal intestines and are deposited in the environment through fecal excrement. At the watershed scale, the origin and intensity of fecal bacteria vary widely and are contributed to waterbodies through direct deposition, diffuse pollution and effluent discharges. The agricultural industry uses a wide variety of practices (i.e., manure land application, free roaming animals allowed in streams, etc.), many of which provide potential pathways for fecal bacteria to
526
migrate to waterbodies (Thiagarajan et al. 2007). In areas dominated by pasture land in Nebraska, wildlife and cattle have been found to contribute a significant amount of fecal bacteria present in a stream (Vogel et al. 2007). Land applied farm animal manure and poultry litter may directly release fecal bacteria to surface runoff during storm events (Guber et al. 2006; McDowell 2006) which may be subsequently introduced into nearby streams. The intensity of fecal micro-organisms in various animal manure are variable, and poultry litters generally have concentrations several orders of magnitude greater than swine or bovine (Unc and Goss 2004; Soupir et al. 2006). Furthermore, fecal bacteria from animal manure, including poultry litter, may survive in soils (Habteselassie et al. 2008) for 4 to 8 weeks after land application (Schumacher 2004). The transport of surviving bacteria from soils to waterbodies potentially adds to the increased bacteria count observed during storm events (Edwards et al. 1997). Large urbanized watersheds might have a greater influx of fecal bacteria from point sources, such as effluent discharges, rather than non-point sources (Servais et al. 2007). The typical influent into WWTPs has about 107 CFU 100 mL−1 of fecal bacteria, whereas the typical effluent from advanced secondary treatment has
