The Montana Fish, Wildlife & Parks Commission agreed today to close the middle reach of the upper Big Hole River, a 28-mile stretch, to all angling due to extremely low water conditions and high water temperatures that threaten the river's native Arctic grayling population. The closure will take effect at midnight, Wednesday, July 26. The upper reach of the Big Hole River, a 19-mile stretch from Rock Creek Road bridge to the mouth of the North Fork, has been closed to angling since July 1.
"Conditions have continued to deteriorate over the last couple of weeks to the point that the flow and water temperatures in this middle stretch of the river are now at levels that severely stress the river's grayling and that could be detrimental in the long-term to this population of fish," said FWP Fisheries Division chief Larry Peterman.
The combined water flows and temperatures recorded in the middle reach of the Big Hole are similar to levels recorded in 1994 when a serious fish kill occurred near the mouth of Pintler Creek.
The Big Hole Drought Management Plan separates the Big Hole River into three "drought emergency" reaches. Today's closure encompasses the middle reach from the mouth of the North Fork to Dickie Bridge, just upstream from the community of Wise River. This reach is critical summer grayling habitat. The upper-most reach of the river, closed effective July 1, includes most of the river's grayling spawning and rearing habitat.
Peterman said the stream flow near the Mudd Creek Gage has fallen to 55 cubic feet per second. In addition, water temperatures have exceeded 70F for three consecutive days at one location near the Christensen Ranch for more than eight hours per day.
The Big Hole River Drought Management Plan recommends closure when flows decrease to 60 cfs or temperatures exceed 70F for over eight hours per day for three consecutive days.
"The hay crop in the area is being harvested and most irrigation is over for the summer, so we aren't anticipating any significant benefit from reductions in irrigation at this time," Peterman said. Irrigators in the basin participate in the drought response plan and have played an important role in helping to keep water in the Big Hole River in past droughts. "When the going gets tough, it is this kind of cooperative effort represented by the Big Hole Drought Management Plan that makes the difference," he said. "Anything we do now to conserve and protect these wild, native fish, will pay dividends in future years."
The Big Hole Drought Management Plan was developed by the Big Hole Watershed Committee, a group of volunteers representing agriculture, municipalities, business, conservationists, anglers and federal, state and local agencies.
Once abundant in the Missouri River above Great Falls, Montana's native fluvial, or river-dwelling, Arctic grayling are now restricted to the upper Big Hole River. The population represents the last remaining native population of river-dwelling Arctic grayling in the lower 48 states. Introductions of grayling into some Missouri River tributaries have recently been made to expand its present range.
Peterman said the closure of the upper and middle reaches of the Big Hole will remain in effect throughout the summer. Hot, dry, windy conditions are expected to further impact the river flow.
The popular sport fishery of the lower reach from Dickie Bridge to the mouth of the Big Hole remains open to angling at this time. The flow is currently 262 cfs at the Melrose Gage. The Drought Plan calls for closure of this reach at 150 cfs. "Anglers should be aware of low-flow conditions and are urged to limit their fishing to the morning hours when water temperatures are generally cool," said Dick Oswald, FWP fisheries biologist in Dillon.