Lake Merwin Water Level
Washington · updated daily from the U.S. Geological Survey
234.56 ft
Lake Merwin is low for this time of year and rising (+0.21 ft in the last 7 days).
Change since yesterday: +0.25 ft
Reading as of 2026-08-14 · higher than 8% of August readings on record
Where Lake Merwin sits historically
Today's level compared with every reading in our 5.0-year record for this lake.
Since yesterday
+0.25 ft
7-day change
+0.21 ft
30-day change
-1.48 ft
1-year change
-1.36 ft
Last 30 days
Last 12 months
Full history (5.0 years)
Lake Merwin records and averages
| Current level | 234.56 ft |
|---|---|
| Record high | 239.27 ft (2024-08-12) |
| Record low | 218.52 ft (2022-01-25) |
| Average of all readings | 234.29 ft |
| Data span | 5.0 years (1,817 readings) |
Frequently asked questions
Is Lake Merwin full right now?
As of 2026-08-14, Lake Merwin sits at 234.56 ft, which is low for this time of year.Over the past 30 days the level has fallen 1.48 ft.
What is the water level at Lake Merwin today?
The most recent reading is 234.56 ft (2026-08-14), sourced from the U.S. Geological Survey. Readings on this page refresh automatically as the agency publishes new data.
What is the highest Lake Merwin has ever been?
The highest level in our records is 239.27 ft on 2024-08-12. The lowest is 218.52 ft on 2022-01-25. Our record covers about 5.0 years of readings.
Is Lake Merwin low for this time of year?
Compared with every August in our records, the current level is higher than 8% of them — low 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.
Why is Lake Merwin changing right now?
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. Lake Merwin has fallen 1.48 ft over the past 30 days. For the operational reason on any given week, check the U.S. Geological Survey directly.
How much has Lake Merwin changed over the past year?
The level is -1.36 ft compared with this date last year (234.56 ft today). The full-history chart above covers 5.0 years, with a record high of 239.27 ft and a record low of 218.52 ft.
Nearby lakes in Washington
Source: the U.S. Geological Survey. Readings are provisional and subject to revision by the publishing agency. All Washington lake levels.