Setting an effective TMDL: Sediment loading and effects of suspended sediment on fish

• Published in: Journal of the American Water Resources Association Vol. 39; no. 5; pp. 1005 - 1015
• Main Authors: VONDRACEK, Bruce, ZIMMERMAN, Julie K. H, WESTRA, John V
• Format: Journal Article
• Language: English
• Published: Middleburg, VA American Water Resources Association 01.10.2003
• Subjects: Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Exact sciences and technology; Freshwater; Hydrology; Hydrology. Hydrogeology; Pollution, environment geology; Salmo trutta; USA, Minnesota, Chippewa R; Minnesota; Chippewa County Minnesota; United States; Swift County Minnesota; USA, Minnesota, Wells Creek; rivers; models; turbidity; Chordata; simulation; streams; transport; indicators; pollution; North America; drainage basins; Vertebrata; suspended materials; pesticides; Pisces; fish; drainage; sediments
• DOI: 10.1111/j.1752-1688.2003.tb03688.x
• ISSN: 1093-474X

Estimates of sediment loading from the basin-scale agricultural model, Agricultural Drainage and Pesticide Transport, were combined with information on the effects of sediment on fish assemblages in relation to a level proposed by the Minnesota Pollution Control Agency to model total sediment load in two basins in the state that included a cool-water stream and a warm-water stream, respectively. In each study area, land managers were surveyed to identify field locations, livestock systems, crop rotations, production practices, and tillage and nutrient practices, and model estimates of sediment losses from pasture systems and managed intensive grazing systems were compared to field data. Results showed that mean daily sediment concentrations over the 50-yr simulation period were above the threshold for sublethal effects to fish in both streams, but were not lethal for an exposure of less than 1 d. The mean annual number of events with sublethal or lethal sediment concentrations to fish was higher in the cool-water stream than in the warm-water stream. Overall, the sensitivity of the fish assemblage to suspended sediment and the duration of exposure were critical components to consider when setting a total maximum daily load (TMDL) for suspended sediment.