Reservoirs and their associated dams affect aquatic and riparian environments along their tail waters. Variable flows, low flows, and the loss of spring time flushing flows can have negative effects on aquatic environments below reservoirs. Minimum reservoir releases are used within the Platte River Basin to benefit downstream aquatic and riparian habitats.
Within the Lower Laramie subbasin minimum release requirements have been placed on Grayrocks Dam. Information regarding Grayrocks Dam is summarized in the following table. Click here to view a map of the locations of all five Platte River Basin minimum reservoir release sites.
Name |
Owner |
Minimum reservoir release (cubic feet per second) |
| Grayrocks Dam |
Basin Electric Power Cooperative |
Reference: 1978 Agreement of Settlement and Compromise and the Modified North Platte Decree, Exhibit 3 |
Natural flow is measured at the gage above Grayrocks Reservoir.
Senior rights downstream of Grayrocks Reservoir total 24.69 cfs. |
| Whenever there is less than 29.575 cubic feet per second of natural flow at the gage above Grayrocks Reservoir. |
As measured at the gage below Grayrocks Reservoir. |
| When storage in Grayrocks Reservoir is at least 50,000 acre-feet |
October 1 to March 31 - 40 cubic feet per second |
| April 1 to April 30 - 50 cubic feet per second |
| May 1 to September 30 - minimum flow of whichever is greater: 40 cubic feet per second or 75 percent of natural flow at the gage above Grayrocks Reservoir, after all rights have been filled except the Grayrocks Reservoir storage right and the direct flow right for the Laramie River Station power plant; release rates are not to exceed 200 cubic feet per second |
| When storage in Grayrocks Reservoir is less than 50,000 acre-feet |
No minimum release |
| As measured at the Ft. Laramie Gauge. |
| When storage in Grayrocks Reservoir is at least 50,000 acre/feet |
October 1 to March 31 - 40 cubic feet per second |
| April 1 to April 30 - 50 cubic feet per second |
| May 1 to September 30 - minimum flow of which ever is greater: 40 cubic feet per second or 75 percent of natural flow at the gage above Grayrocks Reservoir after all rights have been filled except the Grayrocks Reservoir storage right and the direct flow right for the Laramie River Station power plant; release rates are not to exceed 200 cubic feet per second |
| When storage in Grayrocks Reservoir is less than 50,000 acre-feet |
October 1 to March 31 - 20 cubic feet per second |
| April 1 to September 30 - 40 cubic feet per second |
