Flows to drop to 1,750cfs

Inflow forecasts for Yellowtail continue on a downward trend. After last year’s record setting water supply and ample winter storage, spring runoff and precipitation figures continue to tank. As if these low release and poor inflows weren’t bad enough, rampant algae growth is trying the patience of even the most ardent anglers. Ken Frazer, Region 5’s fishery manager, and FWP biologists are investigating what might be done to stifle the algae, and we’ll keep you posted on developments on that front. Last week, after a routine flow measurement performed by USGS, it was discovered releases from the Afterbay were at 1,880cfs rather than the prescribed 2,000cfs. This is a common occurrence when algae is blooming and causing the stage of the river to increase. After consultation with a variety of stakeholders, it was decided to leave the flows at 1,880cfs rather than make the correction back to 2,000cfs seeing that reductions were a certainty. Today at 4pm, flows to the Bighorn River will be reduced from 1,880cfs to 1,750cfs. Reclamation gave us assurances that they would do everything possible to not go below 1,750cfs. As expected, the lake will not fill, and peak lake elevations are only expected to reach a maximum of 3,630ft, a full ten feet lower than full pool. On the upside, fishing is great, and wade fishing is once again a late May and June activity! Hope to see you and your friends on the river soon!

Inflow forecasts continues to worsen

Although most of the state of Montana’s runoff looks to be close to normal, the Bighorn Basin is shaping up to be one of the worst runoff seasons on record.It is almost a certainty that flows to the Bighorn River will be at or below minimums for the foreseeable future, and that lake elevation will peak much, much lower than the last half dozen years.River interests are advised to plan for low flows on the Bighorn this year unless some significant period of precipitation should develop.

Afterbay Rehab work to continue

BILLINGS, Mont. — Rehabilitation of the Yellowtail Afterbay Dam began in September 2011 with work focused on the radial gates and radial gate bays. The contractors, Moltz Constructors Inc. and Engineering Construction Innovations, will be performing similar work on the sluice gates and sluice gate bays beginning the week of May 14.The sluice gate work is expected to take 8 to 12 weeks to complete. During this time, public access to the sluiceway stilling basin on the south abutment of the Afterbay Dam will be restricted. Vehicular access across the Afterbay Dam to the Bighorn River launch site will not be impacted.Releases to the Bighorn River will be maintained through the five radial gates while the work on the sluice gates is occurring, said Chris Gomer, Project Engineer with Reclamation’s Montana Area Office. No fluctuations in releases to the river are anticipated as a result of the work, Gomer added.For additional information, please contact Paula Holwegner of the Bureau of Reclamation at 406-247-7300.

Reclamation issues snowmelt runoff forecast

BILLINGS, Mont. — As of May 1, the Bureau of Reclamation’s forecast of April through July runoff predicted for the Shoshone, Wind, and Bighorn River Basins is as follows: Buffalo Bill Reservoir – Shoshone River April through July inflow to Buffalo Bill Reservoir is forecast at 570,000 acre-feet, which is 84 percent of the 30-year average of 679,000 acre-feet. Approximately 85,000 AF of the forecasted amount flowed into Buffalo Bill Reservoir during April, leaving 485,000 AF of inflow forecasted for May through July. Wind River – April through July snowmelt runoff into the Wind River above Bull Lake Creek is expected to be 290,000 acre-feet, which is 70 percent of the 30-year average of 412,000 acre-feet. Approximately 40,000 AF of the forecasted amount was received during April, leaving 250,000 AF of inflow forecasted for May through July. Bull Lake Reservoir – April through July snowmelt runoff into Bull Lake Reservoir from Bull Lake Creek is expected to be 100,000 acre-feet, which is 71 percent of the 30-year average of 141,000 acre-feet. Approximately 8,000 AF of the forecasted amount flowed into Bull Lake during April, leaving 92,000 AF of inflow forecasted for May through July. Boysen Reservoir – Wind River April through July inflow to Boysen Reservoir is forecast at 250,000 acre-feet, which is 44 percent of the 30-year average of 574,000 acre-feet. Approximately 52,000 AF of the forecasted amount flowed into Boysen Reservoir during April, leaving 198,000 AF of inflow forecasted for May through July. Bighorn Lake (Yellowtail Reservoir) – April through July inflow to Yellowtail Reservoir is forecast at 750,000 acre-feet, which is 66 percent of the 30-year average of 1,138,500 AF. Approximately 150,000 AF of the forecasted amount flowed into Yellowtail Reservoir during April, leaving 600,000 AF of inflow forecasted for May through July.An acre-foot is the amount of water needed to cover 1 acre (43,560 square feet) 1 foot deep (325,851 gallons or 1,233.5 cubic meters).For additional information on Buffalo Bill, Boysen and Bull Lake reservoirs, contact Wyoming Area Manager, Coleman W. Smith, Jr., at 307-261-5671.For additional information on Yellowtail Reservoir, contact Montana Area Manager, Dan Jewell, at 406-247-7298.The WYAO uses the most recent 30-year period, 1982 to 2011, to determine averages. For more information on snowmelt forecasts and real-time data, please visit the Great Plains Region’s Water Operations web site at: www.usbr.gov/gp/lakes_reservoirs.

Flows to start dropping today

Snowpack for the Bighorn basin has plummeted to 61 percent of average overall, and runoff continues to look bleak. At our request along with FWP, last week we asked Reclamation to 1) please follow the rule curves which mandate a reduction in releases based on the inflow forecast and 2) reduce releases now to prevent further future reductions. They have complied. Today at 4pm, river releases were reduced from 2,500cfs to 2,250cfs.Tomorrow at 4pm, river releases will be reduced from 2,250cfs to 2,000cfs. Special thanks to Reclamation for making the reductions in the late afternoon during the very busy May season. -Doug