||Estimated Loadings from Seven Michigan Tributaries and Recommendations for Tributary Sampling Strategies
Day, Robert M. ;
||Surface Water Quality Division, Michigan Department of Natural Resources, Lansing, MI.
Water quality ;
Study estimates ;
Monte Carlo method ;
Loading rate ;
Water flow ;
Numerical analysis ;
Site surveys ;
Water pollution sampling ;
||Most EPA libraries have a fiche copy filed under the call number shown. Check with individual libraries about paper copy.
Annual load estimates of twelve parameters from seven Michigan tributaries were calculated from 1984 to 1986. Estimates were calculated by dividing sample concentrations into high and low strata and applying Beale's Ratio Estimator. The greatest annual loads of the twelve parameters usually came from the St. Joseph followed by the Black or Rouge rivers and the lowest annual loads came from either the Pere Marquette or Ontonagon rivers. Monte Carlo studies indicate that flow stratified sampling strategies yield unbiased and relatively precise total phosphorus load estimates when the samples were selected randomly. Strategies that confine sampling to the first half of the year or neglect either the rising area or falling area of the hydrograph will yield biased load estimates. A systematic sampling strategy will insure that each sample within each strata has an equal probability of being selected and usually yields unbiased total phosphorus load estimates. Sample sizes necessary to estimate total phosphorus loads were calculated for four of the seven Michigan tributaries studied using load average and variance predicted by flow variability versus load variability regression equations. This method can be used to provide sample size estimated for many tributaries with little or no prior information about total phosphorus concentrations but is not reliable for the most event responsive rivers.
"Project Nos. S-005741-01-2, S-005741-02-1, S-005741-03"