Paper No. 96008 of the Journal of the American Water Resources Association (formerly Water Resources Bulletin). Discussions are open until October 1, 1997.
POLLUTANT LOADING CAPACITY FOR THE BLACK RWER, CHEHALIS RWER SYSTEM, WASHINGTON1
Version of Record online: 8 JUN 2007
JAWRA Journal of the American Water Resources Association
Volume 33, Issue 2, pages 465–480, April 1997
How to Cite
Pickett, P. J. (1997), POLLUTANT LOADING CAPACITY FOR THE BLACK RWER, CHEHALIS RWER SYSTEM, WASHINGTON. JAWRA Journal of the American Water Resources Association, 33: 465–480. doi: 10.1111/j.1752-1688.1997.tb03525.x
- Issue online: 8 JUN 2007
- Version of Record online: 8 JUN 2007
- pollution modeling;
- water quality;
- Total Maximum Daily Load;
- waste load allocation;
- Chehalis River;
- nonpoint source pollution;
ABSTRACT: The Black River, a tributary of the Chehalis River in western Washington State, has a history of widespread low dissolved oxygen (DO), anoxia in some locations, and fish kills. As part of a Total Maximum Daily Load (TMDL) study, environmental data were collected during two summer dry seasons and simulations were conducted with the WASP5 model to assess the effect of biochemical oxygen demand (BOD), ammonia, and nutrient loads on DO in the Black River. DO levels were below the State water quality regulatory criterion of 8.0 mg/L in almost all locations during the study. The slow middle reach of the river showed stratified conditions, with anoxia in some of the deepest pools. Based on model simulations, DO was found to still fall below the 8.0 mg/L criterion in the entire mainstem under “natural” conditions, and eutrophication was identified as a potential problem in the middle reach. A TMDL was proposed for BOD and ammonia that would prevent significant degradation of DO in the Black River. To prevent eutrophic conditions in the Black River, a TMDL for total phosphorus was proposed that establishes a protective criterion of 0.05 mg/L for the middle river during the dry low-flow season.