TABLE 5.

E. coli concentrations, fecal concentrations, and percentages of bovine-associated and human-associated fecal concentrations in watersheds with different land use patterns

Land use typeSite name (flow)E. coli concna (CFU/100 ml)Real-time PCR assay result (mg/liter) for:% Spiked plasmid recoveryb% Recoveryc that was
AllBacBoBacHuBacAttributable to bovinesAttributable to humans
Pasture/rural housingNS-1 (low flow)26717.4 ± 8.52.3 ± 1.50.8 ± 0.777 ± 18134
NS-1 (high flow)17,800100 ± 7.615.4 ± 8.919 ± 8.797 ± 11519
NS-3 (low flow)605.6 ± 3.72.3 ± 3.11.2 ± 0.567 ± 194121
NS-3 (high flow)39,600452 ± 68144 ± 3337 ± 7.291 ± 4328
UrbanU2 (low flow)1,96770.9 ± 212.1 ± 1.514 ± 4.085 ± 42321
Resort/forestR07 (low flow)60017.7 ± 6.3NDd0.6 ± 0.363 ± 41ND3
R20 (low flow)3,160231 ± 1.71.2 ± 1.8243 ± 62113 ± 350.5105
  • a Single-sample E. coli concentration.

  • b Percent recovery = (sample spiked with 2.5 × 105 copies − measured copies in unspiked sample)/(2.5 × 105) × 100. The percent recovery was determined for each assay and then averaged.

  • c Percent total = [concentration (mg/liter) of BoBac or HuBac/concentration (mg/liter) of AllBac] × 100.

  • d ND, not detected in this sample.