With mountain snowpack well over average, managers at upstream reservoirs Boysen and Buffalo Bill are stepping up releases in to the Bighorn Lake. In order to accommodate snowmelt runoff, releases out of Yellowtail will need to be increased accordingly.
Starting at 8am on Friday, releases will increase from 6,500cfs to 7,000cfs. Likewise, at 8am on Saturday, releases will increase from 7,000cfs to 7,500cfs.
Citing snowpack in the basin that remains well over 130% of average, Reclamation will be increasing releases to the Bighorn River to 6,500cfs tomorrow at 8am.
Engineers are predicting that the lake level will have to drop to nearly 3,600ft to evacuate enough storage to contain the runoff. To reach this lake level, additional releases may be coming in the weeks ahead, and depend of course, on what Mother Nature has in store for us.
With the upstream reservoirs set to increase their releases in the coming days, and snowpack continuing to remain above 130% of average, Reclamation will increases releases to the Bighorn River by another 500cfs. This will bring the releases up to 6,000cfs starting Tuesday morning at 8am.
from Wyoming Fish and Game
CODY- The Wyoming Game and Fish Department cautions sportsmen and recreationists to be aware of sizeable increases in water flows in the Bighorn River March 25-27 as part of a flushing flow project.
The Bureau of Reclamation will begin releasing additional water from Boysen Reservoir causing flows in the river below Boysen Dam to fluctuate from 475 cubic feet per second to 5000 cfs. Beginning Tuesday, March 25 at 10 p.m., flows released from the dam will increase to 1000 cfs. On March 26, flows will be increased to 2300 cfs at 2 a.m. and further increased to 5000 cfs at approximately 7 a.m. for ten hours before being gradually reduced to and held at 1000 cfs by approximately 4 a.m. March 27.
The department advises the public to be aware of the potential dangers related to flushing flows. Sportsmen wading or floating the river during this time should consider the fluctuating water levels. Areas that can be waded effectively at 500 cfs may not be accessible at 5000 cfs.
“We will be keeping close tabs on water discharge levels and ice conditions in order to ensure the safety of people and property along the Bighorn River,” said Sam Hochhalter, fisheries biologist with the Game and Fish. The flushing flow may be canceled or rescheduled depending on water and ice conditions.
Game and Fish has requested the flushing flow in order to clean fine sediments from fish spawning habitats and to increase production of invertebrates that fish depend on for food. Flushing flows have been a regular occurrence on the river since 2005 and have dramatically improved wild rainbow trout reproduction in the Bighorn River. For more information, contact Sam Hochhalter at 307-527-7125.
As expected, with mountain snowpack in the Bighorn Basin over 130 percent of average, upstream reservoirs preparing to evacuate some of their storage, and the flushing flow from Boysen scheduled for the end of the month, river releases will need to be increased.
Tomorrow morning at 8am, releases will increase from 5,000cfs to 5,500cfs. It is likely that additional releases will be required to meet the end of March target lake elevation of 3,617ft.
At 8am on Thursday morning, releases to the Bighorn River will increase from 4,500cfs to 5,000cfs according to Reclamation officials. Citing still rising inflows reaching as high 8,400cfs, releases will have to be increased if there’s to be any chance of reaching the planned lake elevation of 3,617ft by the end of the month.
Early indications from distant upstream gaging stations show inflow may be starting to subside somewhat, but there’s still 13 feet of storage (roughly 110,000 ac/ft) to evacuate before the end of the month. Reclamation has stated that current release calculations take in to account the annual flushing flow expected from Boysen at the end of this month. (Note: Boysen did not provide a flushing flow last year).
A special thanks to Reclamation engineers Tim and Clayton for their timely updates and communications with stakeholders.
As pretty much expected, mountain snowpack continues to remain well above average. However, the recent warm weather has caused inflows in to Bighorn Lake to rise to 7,400cfs, and more precipitation is forecast for today.
Friends of the Bighorn River strongly desire the end of March lake elevation to be at or below 3,617ft, and applaud Reclamation’s efforts to follow their operating criteria parameters by increasing releases now. Friends also wishes to thank Reclamation for their recent timely correspondence and collaboration.
Starting today at 1pm, released will increase from 3,000cfs to 3,500cfs. Tomorrow morning at 8am, releases will again increase from 3,500cfs to 4,000cfs, and once again Wednesday morning from 4,000cfs to 4,500cfs.
As always, watch this site for the latest information.
Reclamation released the March operating plan this morning and it calls for releases at the end of March to be around 3,420cfs. These releases will increase to approximately 4,000cfs in April and most likely rise to 7,000cfs in May and June. July will see a decrease to 4500cfs, and finally August and fall releases will be closer to 3,000cfs.
It is important to note that the operating plans generally do not show extremes, but values at the end of each month. This means flows could exceed the end of month values for short periods of time.
As always, operating plans can and will change depending on snowpack, snow melt, precipitation, temperature and decisions made by the upstream reservoirs. Watch this site for the latest information.
Unless you’ve been living in a cave since November, you’ll notice that snowpack is a tad above average. In fact, the forecast for April through July inflows in to Bighorn Lake increased a whopping 500,000 acre/ft. That’s just under half the water that can fit in the reservoir!
Accordingly, Reclamation will increase flows on Wednesday morning to 2,715cfs, and to 3,000cfs on Thursday morning. It is almost assured that flows will increase again later in the month.
Enjoy the beautiful weather, and see you on the river!
Stating that streamflow data indicates releases are higher than anticipated (meaning algae has left the system and is not displacing as much water), Reclamation has decided not to adjust flows downward because of the above normal rate of snow accumulation in the Bighorn River basin. As a result, flows have been slowly increasing over that last few weeks to 2,570cfs, and Reclamation has decided to leave those flows at that level. The Bureau did not consult nor notify stakeholders or FWP of this change.
It is worth noting that the lake elevation is 3,627.8 feet and rising. This elevation is slightly above last year’s elevation (a much drier year) and 15 feet above average for this day but only 3 feet above the elevation called for by the operating criteria and rule curves.
[Update: Reclamation did attempt to make contact with FWP regarding this water order change but that attempt failed. Manager Steve Davies has indicated the Bureau will look at better ways to handle situations when attempts to contact FWP fail. A big thanks to Steve for his call and most helpful explanation. -DH]