here is the email from WGFD
North Platte River flushing flow to run for 10 days
CASPER – The Wyoming Game and Fish Department cautions sportsmen to be aware of sizeable increases in water flows in the North Platte River for 10 days beginning March 6 as part of a flushing flow project.
Game and Fish has requested the flushing flow in order to maintain fish spawning habitats and to increase production of invertebrates that fish depend on for food. The Bureau of Reclamation will begin releasing additional water from Gray Reef Reservoir in the early morning hours beginning Monday, March 6. Flows will increase from approximately 500 cubic feet per second (cfs) to 4,000 cfs and will then gradually decrease back to 500 cfs each day, with the maximum flow occurring between 3-7 a.m. Flows from Gray Reef Dam will return to 500 cfs at 10 a.m. each day. The schedule will be repeated through March 15. The flows below Gray Reef Dam will then be stabilized at approximately 500 cfs following completion of the ten day cycle. This schedule may be modified due to river ice.
“Data show these flows are important to trout spawning and to the numbers of trout in the river,” said Matt Hahn, fisheries supervisor for the Casper region. In the past, the trout population had fallen to less than 400 trout per mile, even with stocking. Annual flushing flows began in 1995, and now the trout population averages over 3,500 per mile and annual stocking has been eliminated upstream of Casper.
The Game and Fish Department advises sportsmen and recreationists to be aware of the potential dangers related to flushing flows. Because the flush will span the weekend, there is potential for more people to be wading or floating the river. Those using the river during the flushing flow should consider the fluctuating water levels and be aware that areas that can be waded effectively at 500 cfs may not be safe at 4,000 cfs.
Flushing flows are normally scheduled for completion in March to maximize benefits for spawning rainbow trout.