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HRS Rule, Table 4-13, Page 51613

Surface Water Dilution Weights
Type of surface water bodya Assigned dilution weightb
Descriptor Flow characteristics
Minimal stream Less than 10 cfsc 1
Small to moderate stream 10 to 100 cfs 0.1
Moderate to large stream Greater than 100 to 1,000 cfs 0.01
Large stream to river Greater than 1,000 to 10,000 cfs 0.001
Large river Greater than 10,000 to 100,000 cfs 0.0001
Very large river Greater than 100,000 cfs 0.00001
Coastal tidal watersd Flow not applicable, depth not applicable 0.0001
Shallow ocean zonee or Great Lake Flow not applicable, depth less than 20 feet 0.0001
Moderate depth ocean zonee or Great Lake Flow not applicable, depth 20 to 200 feet 0.00001
Deep ocean zonee or Great Lake Flow not applicable, depth greater than 200 feet 0.000005
3-mile mixing zone in quiet flowing river 10 cfs or greater 0.5

a Treat each lake as a separate type of water body and assign a dilution weight as specified in text.

b Do not round to nearest integer.

c cfs = cubic feet per second.

d Embayments, harbors, sounds, estuaries, back bays, lagoons, wetlands, etc., seaward from mouths of rivers and landward from baseline of Territorial Sea.

e Seaward from baseline of Territorial Sea. This baseline represents the generalized U.S. coastline. It is parallel to the seaward limit of the Territorial Sea and other maritime limits such as the inner boundary of the Federal fisheries jurisdiction and the limit of States jurisdiction under the Submerged Lands Act, as amended.


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