The Big Horn River System Issues Group hosted a meeting at the Lovell Community Center last week to discuss local river and reservoir aquatic health for waters in the area, as well as planned operating criteria for Yellowtail Dam. Stakeholders and interested parties from both Montana and Wyoming attended the meeting, held on April 13, to weigh in on the discussions.
Representatives from the Bureau of Reclamation opened the meeting with a discussion of water supply conditions in the Big Horn Basin and the agency’s proposed spring operating plan for Yellowtail Dam/Big Horn Lake.
Steve Davies, area manager for the bureau, said the forecast for this year’s runoff is two times normal. He noted a record set for March inflows, as well as a record for the highest releases at Yellowtail, noting that so far April is on the same path in terms of higher than average inflows.
Davies said he anticipates “extensive coordination” between agencies during a “big water year like this.” He said the bureau is predicting this to be the third highest runoff year ever, comparable to 1997 and 2011, which are the most recent high water years on record.
Davis said “a lot of preparations are going on behind the scenes” in order to deal with the excessive amount of water expected as the snow melts and runs off the mountains into local waterways. Those preparations include keeping the water in the lake at relatively low levels in order to accommodate the higher than normal inflow during the runoff.
Davies noted that the reservoir is currently low at 3,608 feet of elevation, which is the reason boats at this end of the reservoir are currently unable to launch at Horseshoe Bend. He said about “10 more feet of reservoir” will be required before boats can launch in that area. He said the bureau is currently releasing 10,500 cfs at the opposite end of the reservoir, which is a record release creating lower than normal lake levels for this time of the year. These lower than normal lake levels make it unlikely that the Horseshoe Bend boat launch will have high enough levels for boats to be launched by Memorial Day.
“We know people on the river are impacted and people on the reservoir are impacted,” explained Davies. “We get that. That’s just what happens in a big water year like this one. It’s how we have to deal with it. We have to manage the volume in the reservoir in order to manage what is expected to come in.”
Mahonri Williams of the Wyoming area office gave a brief overview of his expectations for the Buffalo Bill and Boysen reservoirs. He noted that as of April 11, Boysen was 79 percent full, which is 108 percent of average and Buffalo Bill was 64 percent of full, which is 99 percent of average. He said the composite snowpack in the Shoshone River drainage is 151 percent of average, the Wind River drainage is 195 percent and the Bighorn Basin drainage is 123 percent of normal.
“We have really big snowpack right now and the runoff from that will be coming to this area,” he said. “There is lots more now than last year, for sure.”
Williams said the bureau is predicting this to be the third highest runoff year for Buffalo Bill, comparable to 1997 (1,136,000 acre-feet) and 2011 (1,230,400 acre-feet). By comparison the 30-year average is 677,300 acre-feet.
Spring precipitation will add to those amounts and can go “in any direction” for northern Wyoming, Williams said, noting that the trend is currently above average and as much as 204 percent is anticipated this year.
“The amount of spring precipitation will play a big role,” he said. “We will be moving water out to make room for the runoff.”
Williams explained that the bureau sets the lake levels based on anticipated runoff and precipitation levels and though Mother Nature can be unpredictable, officials have a pretty good idea already of what needs to be done to deal with the influx of water.
He noted that a recent “flushing flow” on the Big Horn River released sediment and other debris in connection with the Wilwood operation. He said volunteers rolled up their sleeves during a one-day cleanup operation on the river to remove tires, trash and other debris than came in with the sediment, helping to alleviate the situation considerably. He also noted that, as local canals begin to open, they will take pressure off the river, as well.
Clayton Jordan of the bureau’s Montana area office gave a similar overview of his expectations for the Yellowtail Dam. He said the winter release rate for the dam was 2,610 cfs. He noted that though November was relatively dry in terms of precipitation, inflows in October peaked due to a weather event bringing four feet of rain to the area. He said December and January inflow was below normal releases, noting that ice conditions “were not ideal” creating problems (local flooding) that had to be taken into consideration with all decisions.
He noted that snowpack in the local mountains is “big” but not as high as the record years of 2011 and 1997, reiterating that the “third highest year is expected.”
“We are preparing for the runoff,” said Jordan. “We’re trying to not make it any worse than it has to be.”
Dealing with the higher than average runoff is expected to affect boat launching into June, as well as other recreational activities such as fishing in the area. There was no discussion of how sediment will affect the area this year.
By Patti Carpenter