Moses Lake is a lake in Grant County, Washington. Its water-quality measurements are published by Washington Ecology and shown on this page as reported.

Are there boat ramps on Moses Lake?

Moses Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Crab Creek. Public access is listed as yes.

Can I fish at Moses Lake?

Moses Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Seasons, size and bag limits, and whether you need a license are set by Washington's fish and wildlife agency, so check its current regulations before you go.

Moses Lake

Grant County, WashingtonView map Directions

Washington Ecology publishes the water-quality measurements for Moses Lake. Here is what has been measured.

Phosphorus

20 µg/L

Typical for Washington

Measured by Washington Ecology

Type

Mesotrophic

Trophic class

Trend

Worsening

10 years of samples

Mesotrophic
Impaired · Temperature
Public access

See the measurements Directions Where to stay

Moses Lake in Grant County, Washington has water-quality measurements published by Washington Ecology, shown here as reported. Phosphorus: 20 µg/L.

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Moses Lake is a mesotrophic lake in Grant County, Washington. Overall water quality is declining over recent sampling years. Limited fish-species data available. Public access is available with 1 public boat landing. Compared to the 3 other monitored lakes in Grant County, Moses Lake ranks #4 for water quality.

Source: EPA Water Quality Portal sampling records, WA Ecology, last sampled 2022-10-17. Methodology: how these readings are compared.

Moses Lake has one public boat landing. Vrbo is where to look for cabins and lake homes around Moses Lake, and Booking.com and Expedia search hotels near the lake for your dates.

What Moses Lake is good for

From access and monitoring records, not editorial picks.

Boat launch1 documented ramp

Swimming conditions

Readings only

Low algae

Based on clarity and algae readings from past sampling — there is no live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.

Nutrient and algae readings are not a swimming clearance. Moses Lake is listed impaired under Clean Water Act §303(d) (IR 5) for temperature. Check local advisories before you swim.

Whether Moses Lake is safe to swim in today is a call for the Washington State Department of Ecology and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.

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Water quality measurements for Moses Lake

These are the measurements Washington Ecology publishes for Moses Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.

No clarity data. Phosphorus 20 µg/L. TSI 47.

Water quality readings
Measure	Reading	Where it sits
Water clarity (Secchi depth)		No reading How deep a black-and-white disk stays visible from the surface. Higher is clearer.
Total phosphorus	20µg/L	Good GoodFairPoor
Chlorophyll-a (algae)		No reading The green pigment in algae — a direct measure of how much algae is in the water.
Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a.	47	Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic

Moderate nutrients, good water quality

Ask about Moses Lake

Answers come straight from the public measurements and survey records on this page.

Recreation & Access

Boat Landings

Yes

Public Access

Crab CreekPublic

Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps

Stays via Stay22

Stays near Moses Lake

Compare lakeside cabins, hotels, and vacation rentals near Moses Lake in Grant County, Washington — live availability and prices for your trip. Switch the map to Satellite to see the lake and how close each stay is to the water.

Top-rated places to stay near Moses Lake

Prices for Oct 30–Nov 1, 4 adults. Change dates on the map below.

Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.

Planning a trip? Cabins and lodging at Moses Lake → · more Washington lake trips

Follow Moses Lake’s readings

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Fishing Moses Lake

→ Moses Lake fishing regulations (limits, seasons, special rules)

Water Quality Trend: Worsening

Based on 10 years of monitoring (2012–2022).

Phosphorus
Worsening
+3.2 µg/L/yr10 years

See year-by-year chart →

Reservoir Info (USACE NID)

Moses Lake is a man-made reservoir impounded by the Moses Lake South Dam (completed 1961), built primarily for irrigation on the Crab Creek; earth-type dam, 20 ft tall and 350 ft long.

Normal storage: 50,000 ac-ft
Max storage: 50,000 ac-ft
Drainage area: 2,689.36 sq mi
Hazard class: Low
Owner: BUREAU OF RECLAMATION

All listed purposes: Irrigation;Recreation.

Source: USACE National Inventory of Dams, NID ID WA00128 · Operator website

EPA Impairment Status

Moses Lake is officially listed as impaired under Clean Water Act §303(d) in the 2018 EPA reporting cycle (IR category 5).

Causes of impairment

Temperature

Designated uses not supporting: Aquatic life.

Source: EPA ATTAINS assessment unit WA47119A3I3_02_02 · Official waterbody report

Nearby Lakes in Grant County

Corral Lake—View →Blythe Lake—View →Marsh Unit One—View →Upper Goose Lake—View →Soda Lake—View →Lower Goose Lake—View →

Frequently asked questions about Moses Lake

Where is Moses Lake?: Moses Lake is a lake in Grant County, Washington. Its water-quality measurements are published by Washington Ecology and shown on this page as reported.
What is the water quality of Moses Lake?: Moses Lake in Grant County, Washington has water-quality measurements published by Washington Ecology, shown here as reported. Phosphorus: 20 µg/L.
Is Moses Lake safe to swim in?: Nutrient and algae readings are not a swimming clearance. Moses Lake is listed impaired under Clean Water Act §303(d) (IR 5) for temperature. Check local advisories before you swim.
Are there boat ramps on Moses Lake?: Moses Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Crab Creek. Public access is listed as yes.
Can I fish at Moses Lake?: Moses Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Seasons, size and bag limits, and whether you need a license are set by Washington's fish and wildlife agency, so check its current regulations before you go.

Explore Moses Lake across LakeQuality

Wakesurfing on Moses Lake

Depth, room, public access, and the state wake-sport rules

Lake Fishing Forecast

Species activity outlook by water temperature and season

Washington Lake Trips

Where to stay at Washington's top lakes, each with its readings

The State of Washington's Lakes

Washington's cleanest lakes, ranked on agency measurements

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All Washington lakes

Every Washington lake with its Washington Ecology measurements

Lake water quality by country

Official ratings and named-lake measurements

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Where this data comes from

65 measurements from 1 monitoring station, 2012–2022. Retrieved from the EPA Water Quality Portal on 2026-08-02.

Collected and reported by

Bureau of Reclamation1119USBR_WQX65 samples · 2012–2022

Analytical methods

Phosphorus by Single Reagent Colorimetry
Turbidity by Nephelometry

Monitoring station identifiers (1)

1119USBR_WQX-CBP071

EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from and data sources.