Updated September 21, 2026

Data through 7-day lookback: September 13 to September 20; latest weekly hydrologic update through September 13

Powell rises, Mead falls, and storage stays tight

Powell rises, Mead falls, and storage stays tight. Weekly Colorado River Basin update on Powell, Mead, storage, operations, and weather.

The two main reservoirs moved in opposite directions from September 13 to September 20. USBR daily data show Powell at 3,517.21 feet and 5.107 million acre-feet, up 0.34 feet and 18,620 acre-feet. Mead fell to 1,038.22 feet and 6.856 million acre-feet, down 0.56 feet and 38,280 acre-feet. Together, Powell and Mead held about 11.963 million acre-feet, a net loss of 19,660 acre-feet. [1]

The latest Reclamation weekly update, released September 14 with conditions through September 13, put total Colorado River system contents at 18.039 million acre-feet, or 31% of capacity. A year earlier the system held 21.957 million acre-feet, or 38%. The same report lowered its water-year Powell inflow forecast by 68,000 acre-feet to 3.516 million acre-feet, just 37% of normal. [2]

New September 24-Month Study scenarios show the tradeoff managers face in 2027. Under median hydrology, a 6.0 million acre-foot Powell release would leave more water at Powell, while a 7.0 million acre-foot release would support a higher Mead elevation. Reclamation presents both cases as modeled scenarios, not a final release decision. [3] [4] [5] [6]

The forecast is warmer and wetter, but it is not a reservoir recovery signal. NOAA CPC's September 20 outlook favors above-normal temperature and precipitation categories across the core basin states for September 26-30 and September 28-October 4. Confidence falls from 3 out of 5 in the first window to 2 out of 5 in the second, and the current Week-2 outlook posts no Colorado River Basin hazard. [7] [8] [9] [10]

Why the new rules matter now

One rising reservoir does not mean the system recovered. Powell gained water during the lookback, but Mead and Flaming Gorge moved lower and combined Powell-Mead storage still declined.

The rules now match the reservoir chart
Reclamation set 2027-2028 operations around protecting Glen Canyon reliability near 3,510 feet. Powell ended September 20 at 3,517.21 feet, so the operating-protection line remains close enough to shape daily interpretation. [1] [6]
Powell rose, but the pair still lost storage
Powell gained 18,620 acre-feet while Mead lost 38,280 acre-feet from September 13 to September 20, leaving the pair near 11.963 million acre-feet and down 19,660 acre-feet overall. [1]
System storage is lower than last year
The September 14 weekly update put total Colorado River system contents at 18.039 million acre-feet, or 31% of capacity. Last year at the same point, the system held 21.957 million acre-feet, or 38%. [2]

What would change my view: sustained Powell inflow above release, Mead and Powell combined storage flattening for more than a few days, or a final 2027 release determination that materially changes the modeled path. [1] [3] [6] [7]

Powell remains just above the 3,510-foot operating line

Powell ended September 20 at 3,517.21 feet, below the post-initial-fill operating low set in April 2023 and 7.21 feet above Reclamation's 3,510-foot operating-protection level.

7-day elevation change

Lake Powell: Up 0.34 ft
Lake Mead: Down 0.56 ft
Flaming Gorge: Down 0.56 ft

September 20 value vs September 13 value

Metric	September 13 value	September 20 value	Change	Why it matters
Lake Powell elevation	3,516.87 ft	3,517.21 ft	+0.34 ft	A small weekly rise leaves Powell 7.21 ft above Reclamation's 3,510-ft operating-protection level.
Lake Mead elevation	1,038.78 ft	1,038.22 ft	-0.56 ft	Still below 1,040 ft and 3.22 ft above the 1,035-ft Hoover power-capacity reference line.
Mead + Powell storage	11.983 MAF	11.963 MAF	-0.020 MAF	The two main reservoirs lost 19,660 acre-feet from September 13 to September 20.
Flaming Gorge elevation	6,008.66 ft	6,008.10 ft	-0.56 ft	Upstream support storage also moved lower, down 17,340 acre-feet over seven days.

Recent basin updates

September 20, 2026: Warm and wetter odds continue into early October
NOAA CPC favors above-normal temperature and precipitation categories across the core Colorado River Basin states for September 26-30 and September 28-October 4. Forecast confidence drops from 3 out of 5 to 2 out of 5, and no basin hazard is posted for Week 2.
NOAA CPC
September 20, 2026: Powell rises while Mead loses more storage
USBR daily data put Powell at 3,517.21 feet and 5.107 million acre-feet, while Mead was at 1,038.22 feet and 6.856 million acre-feet. Powell gained 18,620 acre-feet, Mead lost 38,280 acre-feet, and the pair ended the seven-day lookback down 19,660 acre-feet.
Bureau of Reclamation
September 17, 2026: September models show the 2027 Powell-Mead tradeoff
Reclamation published September 24-Month Study scenarios for 6.0 and 7.0 million acre-foot Powell releases under median hydrology. The lower release protects more water at Powell; the higher release supports Mead. The studies are modeled scenarios, not a final release determination.
Bureau of Reclamation

Weather outlook

Sources checked September 21, 2026.

Storage impact: Cautious
Powell rose, but Mead and Flaming Gorge fell; combined Powell-Mead storage still declined by 19,660 acre-feet.
Heat pressure: High
CPC favors above-normal temperatures across the core basin states in both the 6-10 and 8-14 day windows.
Storm help: Mixed
Above-normal precipitation is favored across the core basin states, but the Week-2 outlook posts no basin hazard and confidence drops later in the period.

Warm and wetter odds continue in the 6-10 day outlook CPC favors above-normal precipitation and temperatures across the core Colorado River Basin states. Chances for above-normal precipitation exceed 50% in parts of the Southwest. Late-season precipitation can help local demand and soils, but it is not enough by itself to reverse low mainstem storage.

September 28-October 4, 2026: The warm-wet tilt continues, with lower confidence.

West Water Watch read

The practical takeaway: Powell gained water, but Mead lost more than Powell gained, so combined storage still moved lower. Wetter odds may help local conditions, but the system remains stressed.

News review completed September 26, 2026.