The Region 3 Supervisor and Fisheries staff for Montana Fish, Wildlife & Parks are requesting that anglers and landowners along the Red Rock River from Lima Reservoir to Clark Canyon Reservoir refrain from fishing for the duration of the 2001 fishing season due to extremely low stream flows and high water temperatures.
FWP is also requesting the assistance of Red Rock River landowners in the implementation of this voluntary closure as anglers approach them for access through their property. Voluntary compliance with this request could postpone mandatory closure of the Red Rock River to angling until the fall spawning season mandates further restrictions to protect the river’s trout populations, according to Pat Flowers, FWP Region 3 Supervisor.
Flow releases from Lima Reservoir on July 13 were dropped dramatically from about 375 cubic feet per second (cfs) to 121 cfs as reservoir storage became very limited, according to Dick Oswald, FWP area fisheries biologist. By July 17, flow releases were further reduced to match reservoir inflow at about 37 cfs as the reservoir storage pool was fully depleted.
“The last time this condition occurred was 1988 when Red Rock River between Dell and Lima was totally dewatered in early July, and did not see a return to flow until May of 1989,” Oswald said.
FWP considers the Red Rock fishery very fragile and vulnerable at this time. Fish populations are stressed due to crowding, predation and limited habitat availability under the low flows.
“High water temperature compounds this cumulative stress and reduces the survivability of individual fish,” Oswald said. “Some stretches of the Red Rock River are serving as ‘oases’ or ‘refuges’ right now where limited trout numbers are capable of surviving under these severely limited flows.”
FWP fisheries personnel monitored Red Rock River flows and temperatures as well as angler use since flows were severely reduced on July 17. Natural valley floor springs and irrigation return flow have maintained 30 cfs at the Briggs Ranch and 100 cfs and higher flows approaching Clark Canyon Reservoir. Some river reaches near Dell are barely maintaining, with flows in the 10 to 15 cfs range. By July 30, flow had become intermittent in the river reach between Dell and Kidd with flows as low as 1.0 cfs and afternoon water temperatures exceeding 80 degrees measured upstream from Dell.
In 1988, brown trout populations of 1,300 per mile dropped drastically and had only recovered to 200 per mile by 1990 in the Dell vicinity. Substantial declines in brown trout numbers are expected following the current year’s low flows.