Abstract
Alternative measures of terrestrial pollutant loading were investigated to identify those that are better predictors of water quality in urban streams. Results from 18 watersheds with the same climatic conditions show that the density of terrestrial fecal-coliform loading is a better indicator of median instream concentrations than total terrestrial fecal-coliform loading. Watersheds with fecal-coliform loading densities less than around
2×
1011
cfu
km−2
day−1
generally had median instream concentrations less than the reference water-quality standard of 400 cfu/100 mL. Median instream concentrations were also less than the reference water-quality standard for population densities less than around
400 persons
km−2
. For any given terrestrial loading intensity or population density, summer conditions of high rainfall and high temperature generally resulted in the greatest water-quality impacts. These results are particularly useful in determining terrestrial loading reductions in support of TMDLs, and in focusing best management practices.
