Castle Lake

Name: Castle Lake (Washington) water level
Creator: U.S. Geological Survey

near Mount St. Helens, WA · Washington · USGS gauge

Water level · NGVD29

2,577.71FT

Gauge elevation · no % full published

7 days ±0.00 ft30 days −0.04 ft

Reading for Oct 25, 2026, 18:45 UTC · page refreshed Oct 25, 21:16 UTC
Source: U.S. Geological Survey (Water Data for the Nation)

Worth going today?Today

Windy or wet – use caution

Light wind, 93% chance of rain

Wind7 mph

Rain93%

Temp46°F

Level2,577.7 ft

TodayRain · 46°F
SSE 7 mph · rain 93%

TonightRain · 41°F
SSE 3 to 8 mph · rain 86%

NWS forecast for the gauge location. Good = wind ≤ 10 mph and rain ≤ 30%; storms are flagged. Not safety advice – check local conditions, closures and warnings.

Field notes

Castle Lake's latest daily level (Oct 25, 2026) is 2,577.71 (NGVD29) ft.

The level has been roughly steady over the past week (±0.00 ft).

Readings come from the USGS gauge “CASTLE LAKE NEAR MOUNT ST. HELENS, WA”. Gauge elevations are not directly comparable between lakes because each uses its own datum.

Lake facts

Gauge / station	CASTLE LAKE NEAR MOUNT ST. HELENS, WA
Elevation datum	ft (NGVD29)
Gauge location	46.2564, -122.2744

Nearby lakes

Spirit Lake West5 mi E3,441.98 ft−0.62 ft Spirit Lake6 mi E3,442.22 ft—Swift Reservoir15 mi SE952.00 ft−7.00 ft Yale Reservoir16 mi S471.00 ft−2.00 ft Lake Merwin20 mi S230.00 ft+1.00 ft

Common questions

Is Castle Lake rising or falling?

Over the last 7 days it changed ±0.00 ft and over 30 days −0.04 ft.

How full is Castle Lake?

USGS publishes the water surface elevation for this gauge but not a percent-full figure, so we don't show one rather than estimate it.

How often is this page updated?

The page is rebuilt automatically every day from USGS's published data. Values can be revised later by the source agency.

Where does the data come from?

The U.S. Geological Survey's Water Data API (api.waterdata.usgs.gov), which publishes readings from USGS and partner gauges. Forecasts come from the National Weather Service.

Latest instantaneous reading; 7-day, 30-day and year-ago changes compare readings at the same hour. USGS data are provisional and subject to revision. This page is not affiliated with or endorsed by the USGS. See data sources.