Ma. Anderson et al., MODELING THE IMPACT OF BODY-CONTACT RECREATION ON PATHOGEN CONCENTRATIONS IN A SOURCE DRINKING-WATER RESERVOIR, Water research (Oxford), 32(11), 1998, pp. 3293-3306
A modeling study was conducted to evaluate the impact of body-contact
recreation (e.g., water skiing, jet skiing, swimming) on pathogen conc
entrations in a source drinking water reservoir under construction in
eastern Riverside County in Southern California. A hybridized Monte Ca
rlo-finite segment model was used to pl edict pathogen concentrations
in the reservoir resulting from pathogen inputs associated with shed f
ecal material and accidental fecal releases (AFRs). Monte Carlo techni
ques were incorporated into the finite segment model to define charact
eristics about individual recreators which affect pathogen loading to
the reservoir (e.g., infection, pathogen shedding rate, location). Res
ults of simulations are provided in the form of cumulative distributio
n and probability density functions derived from uncertainty analyses.
The model predicted considerable spatial and temporal variability in
pathogen concentrations within the reservoir, with elevated levels of
Cryptosporidium rotavirus, and poliovirus in the epilimnion during per
iods of high recreational use. Predicted Giardia concentrations were l
ower than the other pathogens. Hypolimnetic concentrations of all path
ogens were generally 1-3 orders of magnitude lower than the overlying
epilimnetic concentrations. Model results also suggest that field samp
ling will underestimate the mean, range and variance of pathogen conce
ntrations in the reservoir. The model was further modified to include
a particle tracking scheme to allow for transport of aggregated fecal
material. Results from simulations using this approach demonstrate a p
otential for high pathogen loads due to body-contact recreation period
ically reaching treatment plants. (C) 1998 Elsevier Science Ltd. All r
ights reserved.