05/25/2026
Notice a change in flows? We have an update for you!
The following outflow changes are scheduled for Monday, May 25th :
-Outflows will increase from 10.0 kcfs to 12.5 kcfs at 2000 MDT.
-Outflows will increase from 12.5 kcfs to 15.0 kcfs at 2100 MDT.
-Outflows will increase from 15.0 kcfs to 17.5 kcfs at 2200 MDT.
-Outflows will increase from 17.5 kcfs to 20.0 kcfs at 2300 MDT.
The following outflow changes are scheduled for Tuesday, May 26th :
-Outflows will increase from 20.0 kcfs to 25.0 kcfs at 0000 MDT.
This flow schedule is in accordance with the USFWS Biological Opinion for endangered Kootenai River white sturgeon (KRWS) that requires volume to be discharged from Libby Dam during the spring spawning period. The KRWS Flow Plan Implementation Protocol (FPIP) Technical Team (U.S. Army Corps of Engineers, Bonneville Power Administration, U.S. Fish and Wildlife Service, Kootenai Tribe of Idaho, Montana Fish, Wildlife & Parks, Idaho Department of Fish and Game, and BC Ministry of Water, Land and Resource Stewardship), has recommended the operation described below, and the Corps at Libby Dam will implement the Plan as detailed above beginning this evening.
Details on duration of maximum discharge, as well as discharge and duration during the receding limb of the hydrograph, are provided below. The attached figures (.pdf) are projections for Koocanusa reservoir refill, Libby Dam discharge, and Bonners Ferry flow and stage through the fall, and subject to modification as real time conditions warrant.
Flow notifications will be sent out as flows are reduced towards the summer flat flow of ~10,000 cfs and through the fall.
The Corps’ April-August water supply forecast (WSF) for May is 7.05 million acre-feet (MAF; 116% of average), a forecast with an associated sturgeon volume of 1.17 MAF.
The sturgeon flow augmentation operation will consist of a period of increasing dam outflows (pre-peak) from 10,000 cfs to 25,000 cubic feet per second (cfs) over 2 days (May 24 and 25), a period of peak flows for ~ 14 days, and a period of decreasing flows (post-peak) from 25,000 cfs to ~ 10,000 cfs - the summer “flat flow” - over ~ 14 days . This operation will exhaust the allocated sturgeon volume.
Minimum bull trout flow after the sturgeon flow augmentation operation for the May WSF is 9,000 cfs through September, at which time the minimum flow becomes 6,000 cfs.
Projected pool elevation for Koocanusa Reservoir is ~2,453’ MSL in early/mid-August. Full pool management objective is 2,454’ MSL; maximum pool elevation is 2,459’ MSL.
The end of September target elevation for the May WSF is elevation 2,449’ Median Sea Level (MSL); full pool is 2,454’.
The overall objectives for FPIP flow augmentation operations at Libby Dam are to annually provide a period of peak river flow in the spawning reach near Bonners Ferry during the spring freshet (generally between late May and early June), and to provide a stable to rising thermograph in the river as the discharge from Libby Dam decreases towards the bull trout minimum flow or higher through the summer, along with normative river temperatures as managed with the Selective Withdrawal System (SWS) at the dam.
The timing and duration of flows are intended to provide cues for sturgeon to migrate further upstream from their staging areas, and then cues to spawn on the descending limb of the hydrograph (receding flow, warming water), with the overall goal of providing conditions that will enhance the likelihood for sturgeon to migrate to, and spawn over, rocky substrates that exist upstream of Bonners Ferry.
Discharge temperature will be managed as per usual through the spring and summer.
Water Management Data:
https://water.usace.army.mil/overview/nws/locations/lib
Short term forecasts for Libby Dam elevations and inflow:
http://www.nwrfc.noaa.gov/river/station/flowplot/flowplot.cgi?lid=LYDM8
Short term forecasts for Libby Dam outflow:
http://www.nwrfc.noaa.gov/river/station/flowplot/flowplot.cgi?lid=KBDM8
