River District says Grizzly exchange will provide 500 acre‑feet for Roaring Fork; seeks partnership to protect Shoshone flow

Andy Mueller, general manager at the River District, told Pitkin County commissioners on Dec. 10 that the River District engineered a short‑term water exchange with Twin Lakes that will make about 500 acre‑feet of water available to help the upper Roaring Fork Basin.

The exchange arose after maintenance at Grizzly Reservoir and related operations of Lincoln Creek triggered water‑quality concerns this summer, Mueller said. When the Cameo call on the Colorado River was in effect, Twin Lakes would otherwise have been forced to divert the affected tributary flows through its tunnel; Twin Lakes agreed to take the water through its tunnel while the River District released an equivalent quantity from Wolford Mountain Reservoir and banked about 500 acre‑feet for use in the Roaring Fork over the next three years.

The River District said the 500 acre‑foot bank must be used within three years and no more than 300 acre‑feet may be released in a single year. The district also said it will not charge Pickin County or other local partners for that water; River District staff estimated the value of the exchange at more than $200,000 but said their board supported absorbing the cost because of the water‑quality and basin benefits.

Brendan Langenhuysen, the River District’s director of technical advocacy, described how Grizzly Reservoir and Lincoln Creek concentrated sediment and discoloration this year and how the exchange both prevented those flows from entering the upper Roaring Fork this season and created a stored supply that can be released later to provide flows when the river is most in need.

River District representatives additionally outlined their multi‑year effort to acquire and protect the senior Shoshone power‑plant water right on the Colorado River. They said the plan is to acquire the water rights and then work with the Colorado Water Conservation Board to add an in‑stream flow (ISF) use through a state and water‑court change‑of‑use process. The River District said it is negotiating conditions and has already discussed terms with major trans‑mountain diverters including Denver Water, Aurora and Colorado Springs.

River District officials said they are not proposing to enlarge the Shoshone right but to maintain the status quo flow historically delivered by the hydroelectric plant. They said Shoshone’s senior call provides base flows that benefit municipal and agricultural users, support endangered‑fish recovery in a critical 15‑mile reach downstream and reduce treatment costs and water‑quality impacts for downstream communities.

Commissioners pressed the River District on technical details, including how much of the freed‑up water would flow east if Shoshone were removed, how the Grizzly and other mitigation pools (the district cited a roughly 3,000‑acre‑foot Friant exchange and a 900‑acre‑foot Busk‑Ivanhoe settlement) interact with operations, and what protections will be placed on releases to avoid injury to existing Roaring Fork water users.

River District staff said they have engineering studies and state‑model results that they will share with county counsel and local technical advisers and reiterated a request to coordinate on a shared goal for a “healthy river” definition and an implementation plan. Commissioners and River District staff agreed to continue technical meetings to refine modeling assumptions and to explore joint strategies to obtain and operate water for late‑summer flow support.

The River District representatives also acknowledged strained relations in the past – including prior district water rights in the Crystal drainage that were abandoned in 2012 – and emphasized that future progress will depend on working collaboratively with Pitkin County, local water users and other West Slope partners.

County commissioners requested written summaries of model results (expected flow impacts to the Roaring Fork and the proportion of water that could be carried east under various scenarios), copies of applicable exchange and settlement agreements, and a clear timeline for the Shoshone ISF and water‑rights change process. River District staff agreed to provide the technical materials and to meet again with county technical staff.