Tuesday, September 15, 2009

Big Hole Watershed Committee: killing grayling, again...

Today's Grayling Survival Index = -75. An index of "zero" marks the minimum sustainability point. Below that, recruitment and survival are likely to be so low that the population is in decline.

After a wet, cool summer with near record precipitation for the month of August, flows in the upper Big Hole River are below 30 cubic feet per second. This is well below the lower wetted perimeter of 60 cfs--the level at which the carrying capacity of the river channel habitat rapidly falls off.

Worse yet, it is near the arbitrary "survival flow" of 20 cfs--the level at which grayling cannot even travel from the mainstem river channel to seek refuge in cooler tributary streams ("refugia").

The Watershed Committee has a so-called "Drought Management Plan." Even with the record wet month of August, recent low river flows qualify as a drought. I have not heard that the Watershed Committee has even implemented its "Drought Plan." So much for doing everything it could to save (let alone restore) grayling.

The sooner Upper Missouri watershed fluvial Arctic grayling (i.e. Big Hole River grayling) are listed as an Endangered Species, the sooner the Watershed Committee might get around to the serious business of maintaining in stream flows.

Check out the journalism pieces (video & article) about Big Hole grayling by Jonathon Stumpf at NewWest.

From the August 2009 minutes of the Big Hole Watershed Committee:

Mike Roberts Montana DNRC - Big Hole Precipitation and Streamflow Report
Lower Basin (Dillon) – water year (107%) calendar year (113%), August (133%)
Upper Basin (Wisdom) - water year (109%) calendar year (112%), August (174%)
Above average flows have been observed most of spring and summer.
Lower Basin
Big Hole River at Melrose -- August 18 = 532 cfs (75th %ile)
Upper basin
Big Hole River at Wisdom -- August 18 = 64 cfs (70th %ile)
CCAA flow targets met at all five gages 100% of time with the exception of a few days at Wisdom that dropped below 60 cfs.

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