Lake Levels DailyLake Levels Daily

Lake Merwin Water Level Today

Daily level, distance to full pool and history for Lake Merwin, on the Lewis River in Washington.

Updated · Source: USGS 14219950 Provisional

Water level Provisional

218.00ft

msl · 4:00 PM PST, Nov 8, 2026

  • 21.60 ftbelow full pool (239.6 ft)
  • 0.00 ftin 24 h−7.00 ft in 7 days−12.00 ft in 30 days
215220225230235240245215220225230235240245215220225230235240245
  • Full pool
  • 1 yr ago

Is Lake Merwin full?

No. Lake Merwin is 21.60 ft below full pool (239.6 ft). It is 12.96 ft lower than a year ago (230.96 ft on Nov 8, 2025).

Lake Merwin level history

Full pool 239.6 ft
View data table
DateLevel (ft)% full
Nov 8, 2026218.00—
Nov 7, 2026218.00—
Nov 6, 2026218.00—
Nov 5, 2026218.79—
Nov 4, 2026220.12—
Nov 3, 2026221.38—
Nov 2, 2026223.08—
Nov 1, 2026224.92—
Oct 31, 2026226.00—
Oct 30, 2026226.88—
Oct 29, 2026227.17—
Oct 28, 2026227.67—
Oct 27, 2026228.00—
Oct 26, 2026228.96—
Oct 25, 2026229.75—
Oct 24, 2026229.50—
Oct 23, 2026228.83—
Oct 22, 2026228.75—
Oct 21, 2026228.92—
Oct 20, 2026228.25—
Oct 19, 2026229.21—
Oct 18, 2026229.04—
Oct 17, 2026229.54—
Oct 16, 2026230.00—
Oct 15, 2026230.00—
Oct 14, 2026230.00—
Oct 13, 2026230.00—
Oct 12, 2026229.83—
Oct 11, 2026229.79—
Oct 10, 2026230.00—
Oct 9, 2026230.00—
  • Lake Merwin level
  • Full pool 239.6 ft
  • Above full pool
Source: USGS · Daily averages since 2017

Lake Merwin on Nov 8 in past years

Lake Merwin water level on Nov 8 in past years
YearLevel (ft)vs todayvs full pool
2026today218.00—−21.60 ft
2025230.96+12.96−8.64 ft
2024232.23+14.23−7.37 ft
2023234.35+16.35−5.25 ft
2022234.69+16.69−4.91 ft
2021232.50+14.50−7.10 ft
2020234.00+16.00−5.60 ft
2019232.35+14.35−7.25 ft
2018231.05+13.05−8.55 ft
2017234.85+16.85−4.75 ft

Today’s level is the lowest for Nov 8 in records going back to 2017.

Lake facts

Full pool (conservation pool)
239.6 ft msl
Highest since 2017
239.43 ftApr 20, 2019
Lowest since 2017
218.00 ftNov 6, 2026
Data since
Sep 30, 2017
Dam
Merwin Damcompleted 1953
River
Lewis River
Owned by
PacifiCorp
Dam location
Cowlitz County
Gauge location
45.9712, −122.3851

Dam, river and owner from the National Inventory of Dams (USACE). Records cover Sep 30, 2017 to today (daily averages).

Weather on the lake

  1. This Afternoon54°FHighLow 44°FCalmPatchy Fog
  2. Tonight44°FLowENE 1–5 mphPatchy Fog then Cloudy
  3. Monday55°FHighLow 48°FESE 6 mphRain
  4. Tuesday58°FHighLow 50°FSE 5 mphLight Rain
  5. Wednesday65°FHighLow 49°FE 1–6 mphPartly Sunny
  6. Thursday61°FHighLow 47°FSE 0–5 mphMostly Cloudy then Slight Chance Light Rain
  7. Friday55°FHighLow 47°FSSE 5–8 mphLight Rain

Forecast: National Weather Service for the dam area (45.97, −122.39). Wind speeds are forecasts, not measurements.

Nearby lakes

Quick answers

What is the full pool level of Lake Merwin?
239.6 ft above mean sea level, the top of its conservation pool. Above it, water is released or flows over the spillway of Merwin Dam.
How much does Lake Merwin need to be full?
Lake Merwin needs 21.60 ft more water to reach full pool (239.6 ft), as of Nov 8, 2026.
Is Lake Merwin rising or falling?
It is falling: −7.00 ft in the last 7 days and 0.00 ft in 24 hours, to 218.00 ft on 4:00 PM PST, Nov 8, 2026 (US Geological Survey).
What is the highest level in our data?
Lake Merwin reached 239.43 ft on Apr 20, 2019. The lowest was 218.00 ft on Nov 6, 2026 (USGS data since 2017; older records are not in this data set).
How much has Lake Merwin changed in the last year?
In the last 12 months it ranged from 218.00 ft (Nov 6, 2026) to 238.92 ft (Apr 27, 2026), a swing of 20.92 ft.
How often is this page updated?
This page is updated several times a day with the latest reading from US Geological Survey. The last reading is from 4:00 PM PST, Nov 8, 2026.

Where this data comes from

Reservoir gauge 14219950 of the US Geological Survey (waterdata.usgs.gov). Recent readings are provisional and may be revised. Weather from the National Weather Service. Dam details from the National Inventory of Dams.

Lake Levels Daily is an independent site, not affiliated with TWDB, LCRA, USACE, USGS, NOAA, TVA or any lake operator. Check official sources before making safety decisions.