Em4885 irrigation management practices to protect ground water

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Table 2-2. Water Quality Criteria by Classification (Table 2-3 in Washington Nonpoint Source
Assessment and Management Program, published by Department of Ecology, October 1989)
Parameter AA A B C LAKE
BACTERIA (organisms/100mL)
Freshwater 50.0 100.0 200.0 N/A 50.0
Marine 14.0 14.0 100.0 200.0 N/A
DISSOLVED OXYGEN (mg/L)
Freshwater 9.5 8.0 6.5 N/A **
Marine 7.0 6.0 5.0 4.0 N/A
TEMPERATURE (degrees C)
Freshwater 16.0 18.0 21.0 N/A **
Marine 13.0 16.0 19.0 22.0 N/A
pH
Freshwater 6.5-8.5 6.5-8.5 6.5-8.5 N/A **
Marine 7.0-8.5 7.0-8.5 7.0-8.5 6.5-9.0 N/A
TURBIDITY (NTU) 5.0 5.0 10.0 10.0 5.0
TOXICITY— See Chapter 173-201 WAC for specific numerical and narrative criteria ——
* No change from background
Summary of 1992 Statewide Water Quality Assessment
Figures 2-1 through 2-9 are from the 1992 Assessment. Figure 2-1 summarizes results for rivers
and streams. Note that only 14% of total stream miles in Washington were assessed. However, 46%
of the assessed mileage was found to not support designated uses. Another 6% was threatened.
Figures 2-2 and 2-3 show the major causes impairing the use and the sources of contaminants in
rivers and streams.
The term “threatened waterbody” is used to describe a waterbody that currently supports
its beneficial uses but may not in the future due to nonpoint source pollution. A threatened
waterbody could be a river used for primary contact recreation (swimming) that would
likely be polluted by nearby septic tank systems or other pollution source in the future.
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