Lake Merwin
Lake Merwin in Clark County, Washington is not rated for water quality — its monitoring record does not meet the evidence bar. Surface area: 3837 acres.
- Area
- 3,837 acres
- Public access
- Yes
Next lake in Clark County
Swipe left or right on this bar to open the next or previous lake.
Why Lake Merwin has no grade
We grade a lake only when the monitoring record supports a letter: at least three phosphorus or chlorophyll-a samples in the last ten years, scored against EPA National Lakes Assessment thresholds for this lake’s ecoregion. For Lake Merwin, no water-quality sampling on record for this lake.
Not Rated is not an F. It is EPA Integrated Reporting Category 3 — insufficient information. The water here may be excellent or poor; nobody has measured enough of it to say. Everything below that has been measured is still reported on this page.
Sampling is run by WA Ecology and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
Lake Merwin is a 3,837-acre lake in Clark County, Washington. Limited fish-species data available. Public access is available with 1 public boat landing.
Source: EPA Water Quality Portal sampling records, WA Ecology, last sampled recent years. Grade methodology: LakeQuality methodology.
Watch Lake Merwin water quality
Subscribe for LakeQuality updates by email. No spam, unsubscribe anytime.
Swimming Safety
Not ratedElevated nutrients
Not rated for swimming — there is not enough monitoring data to judge this lake
Water quality measurements for Lake Merwin
These readings exist but are not enough for an A–F grade — see why.
No clarity data. Trophic State Index: undefined.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) |
Where to stay near Lake Merwin
Compare lakeside cabins, hotels, and vacation rentals near Lake Merwin in Clark 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 Lake Merwin
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 whole trip? See where to stay at Washington’s top lakes →
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 3,837 acres |
| Public Access | Yes |
No bathymetric survey has been published for Lake Merwin, so its depth is not documented here.
Recreation & Access
- Speelyai Bay ParkPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fishing Lake Merwin
Nearby Lakes in Clark County
Frequently asked questions about Lake Merwin
Where is Lake Merwin?
- Lake Merwin is a lake in Clark County, Washington. LakeQuality has not rated this lake (UNRATED) — no water-quality sampling on record for this lake.
What is the water quality grade for Lake Merwin?
- Lake Merwin in Clark County, Washington is not rated for water quality — its monitoring record does not meet the evidence bar. Surface area: 3837 acres.
Is Lake Merwin safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. Lake Merwin is not rated for water quality — its monitoring record does not meet the evidence bar. Always check local health department advisories before swimming.
Are there boat ramps on Lake Merwin?
- Lake Merwin has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Speelyai Bay Park. Public access is listed as yes.
Explore Lake Merwin across LakeQuality
More Washington Lake Rankings
Other Lakes in Washington
Where this data comes from
Measurements for Lake Merwin come from the EPA Water Quality Portal. Per-sample source details are not recorded for this lake.
Other records on this page
Named boat-access points from the USGS National Boat Ramps inventory