Arrowrock Reservoir, ID

As of 2026-09-30, Arrowrock Reservoir sits at 3125.91 ft, which is below average for this time of year. Over the past 30 days the level has risen 4.59 ft.

The most recent reading at Arrowrock Reservoir is 3125.91 ft (2026-09-30), sourced from the U.S. Bureau of Reclamation. Readings on this page refresh automatically as the agency publishes new data.

The highest level for Arrowrock Reservoir in our records is 3215.07 ft on 2026-04-18. The lowest is 3107.51 ft on 2022-08-15. Our record covers about 4 years of readings.

Compared with every September in our records, the current level is higher than 20% of them, which we classify as below average for this time of year. Seasonal comparison matters more than the raw number, because most reservoirs draw down predictably through late summer and refill over winter and spring.

Reservoir levels move for four main reasons: rainfall and runoff into the basin, releases through the dam for downstream water supply, power generation or flood control, evaporation during hot months, and seasonal drawdown schedules set by the operating agency. Arrowrock Reservoir has risen 4.59 ft over the past 30 days. For the operational reason on any given week, check the U.S. Bureau of Reclamation directly.

Arrowrock Reservoir is -4.71 ft compared with this date last year (3125.91 ft today). The full-history chart above covers 4 years, with a record high of 3215.07 ft and a record low of 3107.51 ft.