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Scientific Investigations Report 2009–5078

Assessment of Eutrophication in the Lower Yakima River Basin, Washington, 2004–07

Table 1. Potential factors affecting algal biomass given adequate-to-high nutrient supply and nontoxic conditions.

[Table modified after U.S. Environmental Protection Agency, 2000a.Abbreviations: ft/s, foot per second; >, greater than; <, less than]

Periphyton biomass
High Low
High current velocity (>0.33 ft/s) Low current velocity (<0.33 ft/s)
Low turbidity/color High turbidity/color
Open canopy Closed canopy
Shallow stream depth Greater stream depth
Minimal scouring High scouring
Limited macroinvertebrate grazing High macroinvertebrate grazing
Gravel or larger substrata Sand or smaller substrata
Smaller depth to width ratio
Phytoplankton biomass
High Low
Low current velocity (<0.33 ft/s) High current velocity (>0.33 ft/s)
Long detention time (>10 days) Short detention time (<10 days)
Low turbidity/color High turbidity/color
Open canopy Closed canopy
Greater stream depth Shallow stream depth
Greater depth to width ratio

For additional information contact:
Director, Oregon Water Science Center
U.S. Geological Survey
2130 SW 5th Avenue
Portland, Oregon 97201

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