As water temperatures rise and stream flows drop the Jefferson River Watershed Council is alerting anglers and water users of potential conservation measures that may be put in place to protect the Jefferson River ecosystem.
According to the JRWC Drought Management Plan, originally approved in 2000 and recently updated for 2012, a series of water flow measurement triggers are used to direct actions involving water usage from the Jefferson River.
The first trigger is a stream flow less than 600 cubic feet per second (cfs) measured at the U.S. Geological Survey water gauge on the Jefferson near Twin Bridges. When the river drops below 600 cfs, the JRWC encourages voluntary conservation measures by water users and awareness among anglers about stress on fish. According to a press release from the Montana Department of Fish, Wildlife and Parks, this level was met on July 31.
When the stream flow drops below 280 cfs at the Twin Bridges gauge, FWP will evaluate the need for mandatory fishing closures on the Jefferson. At this level irrigators and municipal water users will be asked to voluntarily reduce their water consumption, and weekly meetings will be coordinated by the JRWC with users to keep people informed and updated about the water flows so as to maintain a minimum of 50 cfs at the Waterloo gauge. Fishing closures may remain in effect until the flow at Twin Bridges increases or exceeds 300 cfs for seven consecutive days.
According to the drought management plan, in previous drought years the river experienced significant fish loss due to nearly non-existent flow over shallow riffle areas.
In 1988 stream flow was recorded as low as 4 cfs at Silver Star and Waterloo, and as low as 20 cfs in 1992 and 1994.
The third trigger for water conservation measures on the Jefferson as outlined by the drought management plan is a spike in water temperature. Regardless of stream flow, angling will be prohibited from 2 p.m. to 12 a.m. should the water temperature rise above 73 degrees Fahrenheit for three consecutive days. Once implemented, these restrictions will remain in place until Sept. 15 unless designated otherwise by FWP.
FWP communications officer Andrea Jones explained how the decrease in water flows and increase in temperature can impact the river ecosystem.
“Angling would potentially increase that stress, so that’s why in certain circumstances we restrict fishing,” said Jones. “Especially in the afternoon when you have those longer periods of hotter temperatures.”
“We also encourage anglers to limit the amount of time the fish are out of water,” she added. “Limit the fight encouraging stress on fish.”
According to stream flow data collected on Monday, Aug. 13 from the USGS water gauge near Twin Bridges, the flow was listed at approximately 500 cfs and dropping, with temperature reaching nearly 68 degrees. At the gauge near Silver Star, data indicated flows from Sunday, Aug. 12 and Monday, Aug. 13 were less than 300 cfs and dropping, with water temperatures spiking to 74 degrees on those two days.
As of press time mandatory closures on the Jefferson River have not yet been put in place. For more information about river conditions and closures visit the FWP website at www.fwp.mt.gov.