Where is Mountain Lake?

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

Are there campgrounds on Mountain Lake?

Mountain Lake has 1 public campground from USGS The National Map within 5 km, including Mountain Lake Campground. This is a location join, not a booking. Cabins and hotels are listed separately; campsite reservations use the official link when the source provides one.

Mountain Lake

San Juan County, Washington195 acresView map Directions

No nutrient or algae sampling on record from Washington Ecology for this lake.

Area

195 acres

Surface area

Impaired · Dioxins

See the measurements Directions Where to stay

Mountain Lake in San Juan County, Washington has water-quality measurements published by Washington Ecology, shown here as reported. Surface area: 195 acres.

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Mountain Lake is a 195-acre lake in San Juan County, Washington.

Source: EPA Water Quality Portal sampling records, WA Ecology. Methodology: how these readings are compared.

What Mountain Lake is good for

From access and monitoring records, not editorial picks.

Camping1 public campground nearby

Swimming conditions

No reading

Not rated

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

Whether Mountain 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 Mountain Lake

These are the measurements Washington Ecology publishes for Mountain 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. TSI undefined.

Ask about Mountain Lake

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

Lake Details

Surface area

195 acres

No bathymetric survey has been published for Mountain Lake, so its depth is not documented here.

Recreation & Access

Campgrounds

Public campgrounds near Mountain Lake

Mountain Lake Campground0.3 km

Nearest public campgrounds in the USGS National Map inventory, within about 3 miles. An empty list means USGS records no campground that close, which is not the same as camping being unavailable. Where the source gives an official reservation link, it is used; the cabin and hotel search does not cover campsites. More camping lakes

Stays via Stay22

Stays near Mountain Lake

Compare lakeside cabins, hotels, and vacation rentals near Mountain Lake in San Juan 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 Mountain Lake

Prices for Oct 16–18, 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.

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Fishing Mountain Lake

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

EPA Impairment Status

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

Causes of impairment

DioxinsPCBs

Designated uses not supporting: Drinking water, Fish consumption.

Source: EPA ATTAINS assessment unit WA17110003000297_001_001 · Official waterbody report

Nearby Lakes in San Juan County

Cascade Lake1.9 miView →Martin Lake4.5 miView →Horseshoe Lake6.3 miView →Spencer Lake7.1 miView →Hummel Lake10.2 miView →Zyistra Lake—View →

Frequently asked questions about Mountain Lake

Where is Mountain Lake?: Mountain Lake is a lake in San Juan County, Washington. Its water-quality measurements are published by Washington Ecology and shown on this page as reported.
What is the water quality of Mountain Lake?: Mountain Lake in San Juan County, Washington has water-quality measurements published by Washington Ecology, shown here as reported. Surface area: 195 acres.
Is Mountain Lake safe to swim in?: Nutrient and algae readings are not a swimming clearance. Mountain Lake is listed impaired under Clean Water Act §303(d) (IR 5) for dioxins, pCBs. Check local advisories before you swim.
Are there campgrounds on Mountain Lake?: Mountain Lake has 1 public campground from USGS The National Map within 5 km, including Mountain Lake Campground. This is a location join, not a booking. Cabins and hotels are listed separately; campsite reservations use the official link when the source provides one.