Publication Summary

The Washington State Department of Ecology (Ecology) conducted a total maximum daily load (TMDL) study for fecal coliform bacteria in Matriotti Creek, the lower Dungeness River, and tributaries to Dungeness Bay. Due to nonpoint pollution sources, fecal coliform levels were not meeting freshwater quality standards in Matriotti Creek and not meeting marine water quality standards in Dungeness Bay.

The Washington State Department of Ecology (Ecology) conducted a total maximum daily load (TMDL) study for fecal coliform bacteria in Matriotti Creek, the lower Dungeness River, and tributaries to Dungeness Bay. Due to nonpoint pollution sources, fecal coliform levels were not meeting freshwater quality standards in Matriotti Creek and not meeting marine water quality standards in Dungeness Bay.

Ecology, the Jamestown S'Klallam Tribe, and Clallam County staff sampled 35 to 40 stream sites from November 1999 through October 2000. Study results confirmed violations of water quality standards for fecal coliform in Matriotti Creek and Dungeness Bay, Meadowbrook and Cooper creeks, and Golden Sands Slough.

To help locate sources of bacterial pollution, sample sites were chosen to bracket possible pollution sources or specific land uses. Paired t-tests were used to determine stream segments or tributaries where loading sources occurred. Bacterial loading information was used to prioritize bacterial pollution control actions for the Dungeness River and tributaries in the study area.

To protect shellfish harvesting use in Dungeness Bay, the TMDL evaluation proposes a stringent fecal coliform bacteria target for the Dungeness River of a geometric mean of 13 fecal coliform (fc)/100mL and a 90th percentile not to exceed 43 fc/100mL. This represents a 9% reduction in fecal coliform for the mouth of the Dungeness River. Tributaries to Dungeness Bay should meet the current Class AA freshwater standard of a geometric mean of 50 fc/100mL and a 90th percentile of 100 fc/100 mL. This would mean reductions in fecal coliform of 59% for Meadowbrook Creek (mouth), 28% for Cooper Creek, and 82% for Golden Sands Slough.

To meet the TMDL target in the Dungeness River, the fecal coliform bacteria concentrations for Matriotti and Hurd creeks need to have a geometric mean of 60 fc/100mL and a 90th percentile not to exceed 170 fc/100mL. To meet the target levels, a 78% bacterial loading reduction is required in Matriotti Creek. Hurd Creek currently meets the recommended TMDL target concentrations.

A separate TMDL study being conducted for Dungeness Bay will be completed in 2003.

Link to EIM data for User Study ID DUNG/MAT