Map for Fly Fishing at Grey Reef Ranch by Crazy Rainbow in Wyoming
Mar, 18 2020

Grey Reef Flushing Flows 2020

Grey Reef Flushing Flows March 28th– April 6th, 2020

For those of you that are not familiar with the annual Grey Reef Flush let me give you a little insight. The Grey Reef section of the North Platte River is a “tailwater” section meaning it is located behind a dam. In a freestone river meaning a river with no dam rivers will flood or rise in flow during the runoff season. As you can imagine a dam limits the abilities of this natural occurring high water event so the Wyoming Game and Fish along with the Bureau of Reclamation conduct a man-made purge of the system. This “Flushing Flow” has many benefits and they include: removing trash and debris and the removal of sediment. The Removal of sediment allows for a greater success rate during the spawn of Rainbow’s and Cutthroat trout. This is a proven model and has greatly increased the health and trout population of the river and entire river ecosystem for many years now. 


This year’s flush will be slightly different than in years past. The Afterbay (the section of river between Alcova Dam downstream to Grey Reef Dam) will be drained to the old river channel for three days prior to the flush, starting March 25 in order to remove sediment deposits interfering with Grey Reef Dam and allowing for maintenance of the Dam. A large amount of sediment will be expelled following the work being done, sediment will affect water clarity on the Grey Reef section of the river and downstream.


This year we will have a ten day flush, with fluctuating flows from Grey Reef Dam and downstream beginning on Saturday March 28 and ending on Monday April 6. Flows will go from 500 CFS (cubic feet per second) to 4,000 CFS throughout the 24 hour day. The flow schedule will be as follows: 


HOURS Outflow (in CFS) 

00:01- 01:00 500 

01:00- 03:00 2000 

03:00- 07:00 4000

 07:00- 08:00 3000 

08:00- 09:00 2000 

09:00- 10:00 1000 

10:00- 00:00 500


 *Schedule may change due to river ice Anglers and others are encouraged to use caution when on or near the North Platte River during flushing flows, especially when wading. 


Starting April 1, Alcova Reservoir will be raised by 10 feet at a rate of 5 inches per day.


If you are looking at fishing during this time frame I would not be concerned and fishing toward the back end of the flush can be very good. If you are looking at fishing Grey Reef toward the end of the month, I would encourage you to look for other opportunities such as Fremont Canyon or the Miracle Mile or the Big Horn. For those of you that have a trip planned or would be looking at fishing the Reef that first week of April you are in luck. The Flush provides an increase in food such as crawfish, leeches, worms, scuds, and other insects. This will lead to fish being aggressive and gorging themselves of the abundance of food. We often have clients ask or target the back half of the flush for these reasons. 


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