Publication Summary

The report summarizes sampling survey data collected in 2002 by the City of Bellingham. The data support the listing of Whatcom Creek on the state′s 303(d) list of impaired waterbodies. Bacteria problems in the creek and some of its tributaries are primarily from nonpoint sources. The report also recommends fecal coliform Total Maximum Daily Load (TMDL) limits for the creek.

Whatcom Creek is located entirely within the city limits of Bellingham, Washington. Whatcom Creek exceeds state water quality criteria for Class A standards as per Chapter 173-201A WAC. In response to these violations, the City of Bellingham voluntarily conducted a Total Maximum Daily Load (TMDL) study for fecal coliform in the Whatcom Creek watershed from January 2002 through February 2003.

Bacterial (fecal coliform and Escherichia coli) samples were collected every two weeks for the duration of the study. The study design included sampling five mainstem locations and each of the four tributaries entering Whatcom Creek.

The hydrology of the basin was assessed by the placement of two continuous gauging stations. One station is located below the outflow dam on Lake Whatcom, approximately 2,000 feet from the headwaters of the watershed (Derby Pond). The other station is downstream, located at Dupont Street 100 feet upstream of Whatcom Falls.

Fecal coliform violations of Class A standards were documented during both wet and dry weather patterns. Data generated during this study support the listing of Whatcom Creek on the state′s 303(d) list of impaired waterbodies. Pollution is exclusively from diffuse sources (i.e., not municipal or industrial discharges). Potential nonpoint sources of bacteria and other pathogens within Whatcom Creek watershed include stormwater, hobby farms, wildlife, domesticated-pet waste, homeless camps, septic systems, and illegal sewer connections. There has been no attempt in this study to identify individual sources of fecal coliform.

Geometric means and 90th percentiles for bacteria were calculated from the TMDL data. The Statistical Theory of Rollback (Ott, 1995) was applied to determine the percentage of reduction in bacteria loads needed to bring water quality into compliance with water quality standards. Reductions in bacterial loading for the mainstem ranged from 0% to 62%, while tributary reductions ranged from 58% to 88%.