Why are Blue Mesa water levels so low?

Blue Mesa Reservoir is low because the Gunnison River's 2026 snowmelt was the smallest in Reclamation's record for the lake, which runs back to 1981, while releases for the Gunnison Tunnel, the Black Canyon and the river below kept going all summer. From April through July 2026 the lake took in 161,640 acre-feet and released 336,070, and it fell to its lowest level since the reservoir was first filling in 1966.

Blue Mesa Reservoir's water level was 7,415.23 feet above sea level on Oct 28, 2026, 104.17 feet below full pool (7,519.4 feet), with 151,197 acre-feet in storage (16% of capacity). That is 3.5 feet above the lowest reading since the reservoir first reached full pool in July 1970: 7,411.73 feet on Oct 19, 2026, lower than any reading since April 1966, when the reservoir was still filling.

The chart is the lake's level at the end of every year since 1965, from Reclamation's reading at the dam. Full pool is 7,519.4 feet. The table has every year's closing level, change, low and high.

What the reservoir is for

Blue Mesa Dam, built from 1962 to 1966, holds the Gunnison River about 30 miles below the town of Gunnison. It is the storage end of Reclamation's Aspinall Unit. Morrow Point and Crystal dams sit just downstream, and their levels hold nearly steady through the year in Reclamation's operating plans, so a dry year shows up almost entirely at Blue Mesa. Reclamation's record for the dam lists a total capacity of 940,700 acre-feet, the figure this site measures percent full against.

Below Crystal Dam the Gunnison Tunnel, finished in 1909 and 5.8 miles long, can carry up to 1,300 cubic feet per second to the Uncompahgre Project, which serves more than 76,000 acres around Montrose and Delta. What the tunnel does not take flows on through the Black Canyon and down to the Colorado River at Grand Junction. Under Reclamation's 2012 Record of Decision for the Aspinall Unit, releases are also shaped to give the lower Gunnison spring peaks and base flows for endangered fish.

Where the water goes

Reclamation publishes the reservoir's daily inflow, release and evaporation. Summed by water year, October through September, they show where the water went.

Blue Mesa loses little to the air: evaporation has run between 5,686 and 8,815 acre-feet a year since 2000. Its level is set by the snowmelt that comes in and the releases that go out. In wet years the lake ends September above 700,000 acre-feet: 735,807 in 2019 and 732,274 in 2017. In dry years releases run far ahead of inflow: 664,368 acre-feet out against 349,217 in during 2002, 895,101 against 452,535 in 2018, and 715,061 against 528,319 in 2021. Each of those years ended with less than 300,000 acre-feet in the lake on Sep 30.

Worked example: water year 2026

Water year 2026 began with 417,862 acre-feet in the lake on Sep 30, 2025, at 7,467.96 feet. Through the winter the level barely moved, and the year's high came on Jan 20, 2026, at 7,468.56 feet. The site's Upper Colorado River Basin snowpack index, which takes in the Gunnison's mountains, stood at 27% of median on April 1. From April through July, Reclamation counted 155,314 acre-feet of unregulated inflow, the water that would have reached the lake with no reservoirs upstream. That is 24% of the 1991-2020 average and the smallest April-July total in the series, just below 2002's 156,718.

Releases went on. From Apr 1 through Sep 30 the dam released 471,365 acre-feet, an average of about 1,299 cubic feet per second, or about 583,000 gallons a minute (convert cfs to gpm). Over the whole water year 396,098 acre-feet came in, 664,776 went out and 5,686 evaporated, leaving 143,498 acre-feet at 7,413.1 feet on Sep 30, 2026, 55.46 feet below the January high.

On Oct 1, 2026, Reclamation reported Crystal Dam releasing about 770 cubic feet per second: about 560 into the Gunnison Tunnel and about 210 through the Black Canyon. With the US Fish and Wildlife Service it had lowered the base-flow target for the Gunnison at Whitewater, near Grand Junction, to 500 cubic feet per second to conserve storage, a cut the 2012 decision allows in severe drought.

The gauge charted above sits just below the tunnel's diversion, so it reads what the dams released minus what the tunnel took. Gunnison River below Gunnison Tunnel carries the daily flow against its median for the date.

Blue Mesa was not the reservoir drawn down to prop up Lake Powell in 2026. Reclamation's Oct 15, 2026 24-Month Study names Flaming Gorge as the source of the 2026 drought-response releases, 660,000 acre-feet to 1 million acre-feet sent to Lake Powell through April 2027.

How low it has been before

Blue Mesa has reached full pool once, in July 1970, and its record high is 7,519.64 feet on Jul 8, 1970. It has come within a foot of full in 16 other years, most recently at 7,519.15 feet on Jul 25, 2019. The dry spells before 2026 bottomed out between 7,429 and 7,441 feet: 7,430.5 feet on Oct 30, 1977; 7,440.64 feet on Oct 22, 2002; 7,437.18 feet on Mar 10, 2019, after the 2018 drought; and 7,429.49 feet on Nov 1, 2021. Until 2026 the lowest reading after the first fill was 7,427.71 feet on Apr 16, 1984, the seasonal low before a runoff that brought 1.79 million acre-feet into the lake that water year, the most of any year since 1981.

Each time the lake came back: from 7,437.18 feet in March 2019 to 7,519.15 feet that July, and from 7,446.4 feet in January 2023 to 7,512.47 feet that June. The 2026 readings went below all of those lows. The lowest since the reservoir first reached full pool is 7,411.73 feet on Oct 19, 2026, lower than any reading since April 1966, when the reservoir was still filling.

The lines below the lake

Reclamation's record for the dam lists the top of the inactive pool at 7,393 feet and the top of dead storage at 7,358 feet. Water below the inactive line is normally not available for release, and water below the dead storage line cannot be released by gravity at all. On the latest reading the surface stood 22.23 feet above the top of the inactive pool (7,393 feet). Blue Mesa Reservoir water level carries the daily reading and storage, and what carryover storage is explains why the Sep 30 figure in the table above is the one water managers plan around.