Will you be able to float the Boise River this summer?
It was the middle of April. Two million acre-feet of water perched above the Boise River reservoir system, in the form of snow. Those reservoirs only had space for 300,000 acre-feet.
The U.S, Army Corps of Engineers and the Bureau of Reclamation, the two agencies that manage the river, were releasing more than 8,000 cubic feet per second of flows at Glenwood Bridge. Three to four days of 90-degree temperatures like we had in 2012 and the reservoirs would have been nearly filled, forcing the agencies to flood large sections of riverside areas from ParkCenter Boulevard, to Garden City, to Eagle Island and down to Canyon County.
Lt. Col. Damon A. Delarosa with the U.S. Army Corps of Engineers acknowledged to a roomful of reporters and officials that the agencies were behind the curve in releasing water to make space in the three Boise River reservoirs: Lucky Peak, Arrowrock and Anderson Ranch. But if they had tried to catch up after the record inflows in March, they would have had to flood many of the areas they were trying to protect.
He said they were hopeful they could keep the flows under 10,000 cfs at Glenwood. A month later, they had just over 30,000 acre-feet of space left.
Many people, including experts and local hydrologists, were skeptical. So was I.
They were betting on the weather and they won. So did we, because we had to depend on them and flood insurance.
Through June 28, this year has seen the highest inflows into the reservoir system since Arrowrock was built. The nearly 2.9 million acre-feet of water that came in could have filled it 2.4 times by now.
Water was still running into the reservoirs at more than 8,000 cfs on Wednesday, with more than 200,000 acre-feet of water still waiting in the mountains in the form of snow.
The Boise River ran at flood stage from March 7 to June 15 — 100 days of anxiety for its neighbors, another record.
The two federal agencies deserve our praise for getting us through an incredible runoff. The National Weather Service, the USDA Natural Resources Conservation Service and others that provided the data and advice also share the success.
The Corps and the Bureau are still in flood-management mode, with flows just under 5,000 cfs still running at Glenwood.
A threat still remains, at the moment those agencies top off the reservoirs. (They have 25,000 acre-feet of space left.) But the problem is a lot more manageable now.
9,460Highest maximum daily average flows in cubic feet per second at the Glenwood Bridge gauge in 2017
9,560 The record daily average flow in cfs from 1983
2,895,000Boise River reservoir inflow in 2017, measured in acre-feet, a new record
200,000 Amount of water in acre-feet in the form of snow still in the mountains above Boise
There are many people who wanted me to investigate why the federal agencies held on to so much water, suggesting there was scandal in the dual mission of flood control and water storage for irrigation. But Arrowrock and Anderson Ranch dams were built specifically to provide storage for irrigation, and farmers paid back the low-cost federal loans that financed them.
Some irrigation interests also have seen scandal in the way the state has been administering flood flows and their water rights. It has caused them to voice hysterical rhetoric about the flood threat this year.
The Treasure Valley Water Users Association suggested this flood season created the “perfect storm” for exhausting the storage water that farmers and homeowners depend on after natural flows drop off. They are fighting in court with the state over how it counts flood flows. The outcome could affect who owns the water, but it won’t leave farmers high and dry, certainly not this year.
Those of us who like to float the river still have a long wait and uncertainty. Even after the flows drop below 2,500 cfs, local crews are going to have to go in and clear the channel of the trees and debris that would present a threat to safe floating.
The federal river managers showed great skill in getting us through this flood season. But if those who live along the river, ride along the Greenbelt or approve new developments in the floodplain come away thinking these managers will always save us from ourselves, then we all will have failed.
The story on the Boise River remains the same. It’s not a matter of if we will flood, but when.