Howard a Hanson Reservoir water level — Washington
Howard a Hanson Reservoir in Washington was last measured at 1,153.37 ft (datum NGVD29), as of Aug 31, 2026, 1:00 AM (UTC-07:00) (USGS Water Services). Over its recent trend window the level has been falling (−7.8 ft). This reading is provisional and subject to revision.
- % of conservation pool full
- Not reported
- Storage
- 34,230 acre-ft
- Recent trend
- ↓Falling
−7.8 ft over the trend window
Recent trend
Readings this station published between Jun 2, 2026 and Aug 31, 2026 — a 89-day window — downsampled for display.
Data: USGS Water Services (waterservices.usgs.gov) and USACE CWMS Data (cwms-data.usace.army.mil), retrieved 2026-08-31. Both public domain (a work of the U.S. Government, 17 U.S.C. §105).
Source: USGS site 12105800, retrieved Aug 31, 2026, 8:24 AM (UTC+00:00). Official page for this lake →
About this gauge's record
This site's drainage basin covers approximately 220 sq mi of contributing watershed.
The dam behind Howard a Hanson Reservoir
Howard a Hanson Reservoir is held back by Howard A. Hanson Dam (also recorded as Eagle Gorge Dam) , a rockfill embankment — quarried rock placed in compacted layers around a sealing core , standing 235 ft high and running 500 ft along its crest , built across GREEN in King County , near AUBURN . It was completed in 1962 , and is owned by USACE - Seattle District (a federal owner) , to a design credited to CE.
Its recorded primary purpose is flood risk reduction — the pool is drawn down between storms so there is empty space waiting for the next flood, which is why this level can fall in dry weather and climb sharply after rain . It also serves flood risk reduction;fish and wildlife pond;water supply.
Its spillway is gated, so the operator can hold the pool above the spillway crest and meter what leaves. The spillway opening is 90 ft wide.
NID classes it high hazard potential. That describes what a failure would cost downstream — loss of life would be expected — and says nothing about how likely a failure is, or what condition the dam is in.
At its normal pool the reservoir covers about 20,000 acres. NID records a maximum storage of 136,700 acre-ft against a normal storage of 26,000 acre-ft. Its maximum discharge capacity is 129,000 cubic feet per second.
Dam facts: National Inventory of Dams record WA00298 , filed by US Army Corps of Engineers — U.S. Army Corps of Engineers, public domain. Water levels above come from USGS Water Services and are a separate source. (How this dam was matched to this gauge →)
How Howard a Hanson Reservoir compares nearby
4 of 6 nearby lakes with a current trend are also falling right now.
Nearby lakes
The six nearest published lakes by centroid distance (great-circle) — cross-state neighbors included.
| Lake | State | Level | Distance |
|---|---|---|---|
| Mud Mountain Lake | WA | 917.85 ft | 19 km |
| Lake Tapps | WA | 540.91 ft | 31 km |
| Sammamish Lake | WA | 25.72 ft | 41 km |
| South Fork Tolt Reservoir | WA | 1,735.96 ft | 47 km |
| Spada Lake | WA | 1,425.95 ft | 78 km |
| Spirit Lake at Tunnel at Spirit Lake | WA | 3,400.49 ft | 115 km |
Frequently asked questions
- What is the current water level of Howard a Hanson Reservoir?
- As of Aug 31, 2026, 1:00 AM (UTC-07:00), the pool elevation was 1,153.37 ft (datum NGVD29), provisional and subject to revision. See the trend chart above for the recent direction.
- Is Howard a Hanson Reservoir full right now?
- Its managing agency does not publish a %-of-conservation-pool-full figure for this lake, so we show the bare level rather than estimate one.
- Where does this data come from?
- From USGS site 12105800, retrieved Aug 31, 2026, 8:24 AM (UTC+00:00).
More in Washington
See every lake tracked in Washington, or read the methodology behind these figures.