Idaho’s seniority-based rights system of allocating water, and how flood-control releases from reservoirs impact it, is the focus of draft legislation supporters see as a key first step to resolving longstanding conflicts among types of water uses in the growing southwest region.
Irrigation districts, municipal water systems, natural resource managers and others in the greater Boise area want to make sure they continue receiving their rights-backed water allocations amid the increased competition that population growth brings. The parties have gone to court in recent years, and the Idaho Supreme Court as of early June was slated to hear arguments June 20.
Draft legislation presented to an Idaho Legislature panel June 6 would amend Idaho water law to prioritize, during and following flood-control operations, existing water-rights allocations over any sizable new storage capacity created by building or expanding a reservoir.
The panel, including members of natural resource committees in the Idaho House and Senate, voted unanimously June 6 to ask Gov. Butch Otter to call a special session of the full Legislature. The panel stopped short of endorsing the proposal, which would take effect immediately on passage.
Several lawmakers said the legislation would benefit the entire state, though speakers focused on the Boise area primarily.
The Boise River’s three-dam system releases water for flood-control purposes about seven years out of 10. The snowpack runoff that follows, combined with water already in the reservoirs, almost always is enough to satisfy right-holder allocations. But population growth and the prospect of eventually adding significant storage capacity threaten that balance.
Passing the legislation would be an important “step on the ladder” toward a rights-protecting settlement agreement among various types of water users, said Roger Batt, who heads the Treasure Valley Water Users Association. That’s because if it is put into statute, the approach would gain universal acceptance, he said. The association includes irrigation districts, canal and ditch companies.
Will Patterson, a director with Nampa-Meridian Irrigation District, said the proposed legislation would help ensure rights holders get the water they are entitled to after flood-control operations are completed.
“It gives us certainty that the water that is in the reservoirs can be used to irrigate our crops, our lawns and our gardens,” he said.
Idaho Rep. Mat Erpelding, D-Boise, said any solution should protect the streamflow maintenance account - which makes sure Boise River flows don’t drop below a threshold in low-flow season, benefiting fish and the riparian environment.
House Speaker Scott Bedke, R-Oakley, said the “refill” issue has been more challenging on the Boise River than on the Snake River in part because there is more room for error in the nine-dam Snake system. Snake River water users entered a settlement agreement in 2014.
Concerns among users in the Boise system have included transferring water to another river basin, possible future efforts to recharge the aquifer, and prospective new reservoir storage space jumping ahead of established reservoirs in the fill cycle, he said.
The proposed legislation would benefit the growing state overall, Bedke said.
No reservoir construction or expansion projects are imminent in the Boise River system, though expanding Arrowrock Dam has been discussed over the years. The other reservoirs are Anderson Ranch and Lucky Peak.