Friends of the Bighorn River

Despite a full lake (and one that is 10 feet higher than average for
this time of year), inflows have dropped off sharply, and Reclamation
feels river releases must be dropped to now to conserve storage.

At 4pm on Wednesday, river releases will drop from 3,500cfs to 3,250cfs.
At 4pm on Thursday, river releases will drop from 3,250cfs to 3,000cfs.

It is worth noting that during the last four years, lake elevations on
Memorial Day have been 10+ feet higher than minimum boat launch levels
required at Horseshoe Bend, which tends to emphasize the point the
lake is being managed quite conservatively.  The fact that both
minimum probable and most probable operating plans show the SAME
minimum lake elevation of 3,618ft emphasizes the point that the water
is being managed exclusively for the lake and ignoring the river, and
that our hopes of balanced management are still a dream.

Updated:  3:18pm

With runoff and releases from upstream reservoirs decreasing, Bighorn river releases will be dropped to what will hopefully be the final cuts for summer:

On Friday, river releases will be reduced from 4,200cfs to 3,850cfs.
On Monday, river releases will be reduced from 3,850cfs to 3,500cfs.

Yesterday, the USGS graph (found here) showed a 1,000cfs drop in river releases when a drop of 500cfs was indicated. The good news is the river did indeed only dropped 500cfs as planned.

You may recall back when releases had climbed to 9,500cfs, a manual measurement near the Afterbay indicated flows were actually 9,000cfs, a discrepancy of 500cfs.  Since the new gaging equipment at Afterbay had not been calibrated at flows that high, this slight discrepancy of 500cfs was not a surprise.  However, to properly operate and calculate other parameters, an offset of 500cfs along with an increase in flows were put in place to balance things.  Yesterday, this offset was removed from the system but briefly appeared in the USGS calculations for plotting the graph of river releases.

In summary, on Monday, the river dropped only the planned 500cfs.

With continued reductions from upstream reservoirs, streamflows in to Bighorn Lake continue to gradually decrease, requiring further reductions to river releases.

At 4pm on Tuesday, river releases will be reduced from 5,220cfs to 4,700cfs.
At 4pm on Wednesday, river releases will be reduced from 4,700cfs to 4,200cfs.

Many of you noticed the river dropping 1,000cfs today, then bouncing back up 500cfs.  I was floating the river today (fishing and surveying the bank erosion with Mr. Johnson), and will inquire with Reclamation on Tuesday morning and post the findings here.

With inflows continuing to drop off sharply along with some other western hydropower generation issues, river releases will continue to be gradually reduced. Friends of the Bighorn recognize and greatly appreciate the efforts of Reclamation to reduce releases gradually.

On Sunday at 8am river releases will be reduced from 6,220cfs to 5,720cfs.
On Monday at 8am river releases will be reduced from 5,720cfs to 5,220cfs.

It is anticipated further reductions will continue on Tuesday.

As these reductions continue, we would appreciate photos and commentary on stream bank erosion to help document the consequences of the prolonged river releases, higher lake elevations and this extraordinarily wet spring.  Please send any information you have to bighornriver.org@gmail.com

As anticipated, Reclamation will continue to decrease releases to the river over the next few days.

At 4pm today, releases will drop from 8,900cfs to 7,900cfs.
At 8am on Friday, releases will drop from 7,900cfs to 6,900cfs
At 8am on Saturday, releases will drop from 6,900cfs to 6,220cfs

When questioned as to the reason for the morning cuts rather than the preferred afternoon cuts, Reclamation stated the reason for the morning cuts on Fri and Sat are because the dam operators (who work a 4 day week and are off on Fridays) need to be called in special to effect the changes, and it is more convenient for them to make those changes in the morning.

Reclamation has indicated that the high elevation snowmelt is essentially over, causing inflows to drop off sharply. To continue evacuating storage from the flood pool but provide for adequate storage during the rest of the summer, river releases will need to be reduced.

At 4pm today, river releases were reduced from 9,900cfs to 8,900cfs.

Further reductions in releases are expected in the coming days.

Early word from Reclamation indicates flows will gradually start down tomorrow afternoon. Dropping the flows now will help guarantee higher releases through the summer.

Look for the official word tomorrow evening after the Carp Tourney!

To help meet irrigation demands, releases to the Bighorn Canal will increase 100cfs, and releases to the river will drop from 10,000cfs to 9,900cfs in 50cfs increments beginning this afternoon and ending tomorrow morning.

Bighorn Lake filled the conservation pool (lake elevation 3,640ft) at approximately 2:15 this morning.

During the last few weeks, Reclamation engineers have done a commendable job keeping river flows steady despite the recent unstable weather, especially since starting with such a high (and unprecedented) early spring lake level.

However, recent torrential rains across the region have necessitated a slight additional release to the river to control the rate of fill of Bighorn Lake. At 5pm this afternoon, flows were bumped an additional 500cfs to bring river releases to 10,000cfs.

Thanks to everyone who called and/or submitted river reports and observations all of which are most helpful and will be passed along to the appropriate agencies.

A very happy Father's Day to you Dad's this weekend!
 

Got word from Reclamation late this afternoon that "recent streamflow measurements conducted by the USGS are slightly lower than the calculated discharges through the Afterbay control structures." 

To sync the calculated discharges with the actual discharges and produce the desired 9,550cfs, an additional 500cfs was released to the river starting at 4pm this afternoon.