Second Irrigation Along Milk River Basin Likely Due to Recent Precipitation

A photo from July 2020 showing low water levels at Fresno Reservoir (Credit: Josh Margolis)

HAVRE, Mont. (NMB) – The Bureau of Reclamation has released the latest water supply outlook for the Milk River Project, and while the report is more optimistic than it was in the spring, there are still some concerns.

The great news is that reservoir storage at Lake Sherburne, which helps provides water for the system, is nearly full.

Fresno Reservoir, as of Wednesday, was about 13 feet below full pool, placing it at about 48 percent full.

Nelson Reservoir is about eight feet below full pool, making it about 60 percent full.

Irrigation is currently off except for the Fort Belknap Irrigation Project.

Recent precipitation has helped improve the drought outlook slightly, making a second irrigation possible later this summer for about three weeks.

The Milk River Joint Board of Control will decide a restart date at a meeting next week.

At a St. Mary’s Rehabilitation Working Group meeting in Havre on Tuesday, Co-Chair Marko Manoukian said they may only do a 1/3 irrigation, and corn growers may be negatively impacted.

Fresno Reservoir releases are expected to be ramped up when the second irrigation starts. Last year, releases from Fresno were 1,200 cubic feet per second during July. Releases from Fresno to Nelson are currently between 300 and 400 cubic feet per second.

The likelihood of a second irrigation means that the water level of Fresno Reservoir will drop significantly later this summer. The current forecast projects levels to drop to about 31.7 feet below full pool, which is 9,800 acre feet of storage, by early August. That is elevation 2,543.3 feet above sea level, about 12.3 feet from dead pool. Water should come back into Fresno from Sherburne in the late summer and early fall, potentially getting it back to about 11.1 feet below full pool by the end of September (projected elevation 2,563.9 feet, storage of 48,000 acre-feet. This is compared to 39,800 acre-feet in 2021).

Nelson Reservoir is expected to drop to about 13.6 feet below full pool in August (minimum elevation is expected to be August 7th, with elevation of 2,208 feet, storage of 34,000 acre-feet). Levels should remain around that point through September.

Releases from Sherburne between July and September will fluctuate to balance the use of the basin water in accordance with the Boundary Waters Treaty.

Unfortunately, due to issues with the St. Mary’s System including evaporation and spillage of water, not all water transferred from Lake Sherburne makes it into Fresno Reservoir.

This is an issue the St. Mary’s Working Group and Milk River Joint Board are eager  to fix, but a large financial commitment is needed.

Stay tuned in the coming days for more on the St. Mary’s System.

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