A long-awaited plan to conserve water in Central Oregon’s largest river was published Friday, calling for hundreds of millions of dollars to rebuild irrigation systems, and decades more time to broker a compromise between water users and endangered species.

If approved by federal regulators and adopted, the Deschutes Basin Habitat Conservation Plan will allow eight Central Oregon irrigation districts and the city of Prineville to pull water from the Deschutes River without facing lawsuits under the Endangered Species Act. 

The Deschutes has three federally-listed threatened species: the Oregon spotted frog, bull trout and steelhead. The river starts high in the Cascade Mountains near Bend and supplies water to more than 150,000 irrigated acres before it joins with the Columbia River.

A federal biological opinion says for the spotted frog to survive, the Upper Deschutes needs about 600 cubic feet per second of flow. That’s six times the standard amount of water currently released in winter, when flows are diverted to recharge irrigation reservoirs used for agriculture.

Key features of the habitat conservation plan put forward by the districts and the city include costly infrastructure projects and a complicated water barter system. This involves piping canals to increase the efficiency of the most senior irrigation district so that downstream, junior water rights holders can have more water and be less reliant on reservoirs.“The conservation and movement of water in this way will require several decades and several hundred million dollars to complete” the draft plan cautions.

The plan is open to public comment until Nov. 18 and could be approved by May 2020.