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Flow Enhancement

Several years of drought during the 1980's and early 1990's in southwestern Montana impacted fisheries in several major river systems. The impacts of drought include low flows and high water temperatures. The Big Hole River is the last stronghold of fluvial (stream dwelling) Arctic grayling in the lower 48 states. Lethal water temperatures resulting in fish kills were documented during several summers. Aside from direct mortality, high water temperatures severely limit long-term survival of older age classes of Arctic grayling.

Big Hole River, 1988
Photo by Dick Oswald
Montana Fish, Wildlife and Parks
Big Hole River during a drought year (Photo courtesy of Mt. Fish, Wildlife & Parks)

Currently, water is diverted from the Big Hole River for irrigation of hay meadows during early spring through the beginning of July. In many instances, water continues to be diverted after the irrigation season for the purpose of watering livestock. During mid/late summer, these diversions can cause flows in the river to be reduced to almost nothing. On August 29, 1994, flows in the Big Hole River at Wisdom, Montana reached a low of 1.9 cubic feet per second (cfs).  Montana Fish, Wildlife and Parks has determined that a minimum flow of 20 cfs is necessary to provide minimum living conditions.

Well drilling equipment at the project siteIn response to these extremely low flows, a number of Big Hole ranchers voluntarily reduced the amount of water they were diverting, and some ranchers agreed to temporarily close their ditches if alternate stock water was supplied.   Montana Fish, Wildlife and Parks began hauling water to stock tanks on these ranches, ditches were shut down, and Big Hole River flows increased. Hauling water was a labor intensive short term solution, however, it demonstrated that alternative water sources could both water cattle and increase flows in the river.

The long term solution was to develop reliable alternative sources of stock water such as wells and springs. The objective of this project is to improve habitat and environmental conditions for fluvial Arctic grayling by improving flows during mid-summer, especially during drought. Also, this project was the start of cooperative on-the-ground projects with local water users that help their operations become more efficient, give them ownership in fluvial Arctic grayling recovery, and build coalitions toward water conservation. An additional benefit has resulted from wells being located near winter haystacks. Landowners don’t have to haul hay or chop ice, and livestock are not wintered on the river bottom.

Installation of a stocktank for cattle wateringSince 1994 the Partners for Fish and Wildlife Program, along with Montana Fish, Wildlife and Parks and the Beaverhead Conservation District have been drilling wells and developing springs to provide alternative sources of stock water. Additional funding has come from the National Fish and Wildlife Foundation, local donations, and the Sandia Corporation. To date, 14 wells and two springs have been developed on nine ranches allowing seven irrigation ditches to be closed or significantly reduced during periods of low flow. This system was put to the test in 1999 when the river reached 16 cfs on August 25th. Wells were turned on and ditches were closed.  The river increased to a flow of 35-40 cfs.

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