Minimum In-stream (Base) flows established in 1976 for 31 control points in the Chehalis Basin

Enough flow data exists to prepare a "Flow Exceedance Probability Hydrograph" for 16 of those control points.

Example of a Flow Hydrograph

Data/Hydrographs Available for 16 of 31 Sub Basins

No Data Is Available for These 15 Sub-Basins

S. Fork Chehalis River Chehalis R. Elk Cr. to Newaukum River Cedar Creek

90.82 Minimum requirements...

Surface and ground water present

Surface and ground water available

Amount claimed & allocated

Amount actually used

Future needs

System Aquifers

S/G water available for further appropriation

Strategies to increase water supply

The recommend flows can take the following forms:

Minimum instream flows where they

don't already exist

Amend in-stream flows where minimum

instream flows do exist

Fish Emphasis flows: optimize water for fish

(but probably not met in most years)

Out-of-Stream Emphasis flows:

meeting out-of-stream needs while ensuring

adequate water for fish most of the time

Other "Natural Resource Base" flows

Scope of Work

Measure Flows

Compare to existing minimum in-stream flows

Compare to "fish flows" work done last summer

Develop recommendation for flows to be

used for developing Watershed Plan

Same as existing in-stream flows

Higher than existing in-stream flows

Lower than existing in-stream flows

This project will result in recommendations for Voluntary Flow Targets for planning purposes, NOT Regulatory Flows

This project will help us meet our minimum

requirements

A rule (regulation) will have to be written by

Ecology based on the recommendations