Three federal agencies (Bureau of Reclamation, National Marine Fisheries Service, and US Fish & Wildlife) manage water releases out of Prineville Reservoir into the Crooked River. As of last week, they believe flows for fish and wildlife can be maintained through the winter. Prineville Reservoir has a capacity of 148,640 acre feet of water, approximately half of which is guaranteed for irrigation. Water in excess of that at the beginning of irrigation season is “fish water” to be released for the “maximum biological benefit” for fish and wildlife. Irrigation season ends in a month and Prineville Reservoir is still 66% full, leaving plenty of fish water to release during the winter. Keep reading for more details.
The PRVO gauge tracks releases out of Bowman Dam. Below is the water year graph for PRVO. As you can see the current year is pretty unusual. Last winter started out very dry and releases into the Crooked were very low. A series of snow storms in February dramatically changed the picture, to the extent that large and damaging flows had to be released in April to make room for spring snow melt. Those releases breached the 3,000 cfs level where gas bubble disease is often inflicted on resident trout.
Below is the chart for the CAPO gauge just below Prineville and the main irrigation diversions. The agencies hope to keep 100 cfs past this point, which is excellent news. As anyone who has seen the river from Prineville through Smith Rocks knows, this section of river is typically a trickle most of the year creating a hot, oxygen depleted dead zone for trout and migratory anadromous fish. A sustained flow of 100 cfs over many years would be required to create truly healthy habitat, but it will help with fish migration even over a single winter.