Lopez Lake
San Luis Obispo County, California586 acresView mapDirections
SWRCB publishes the water-quality measurements for Lopez Lake. Here is what has been measured.
- Impaired · Biotoxins
- 145 ft max depth
- Limited data
Lopez Lake in San Luis Obispo County, California has water-quality measurements published by SWRCB, shown here as reported. Phosphorus: 615 µg/L. Maximum depth: 145 ft. Surface area: 586 acres.
Lopez Lake is a 586-acre lake in San Luis Obispo County, California with a maximum depth of 145 feet.
Source: EPA Water Quality Portal sampling records, your state environmental agency, last sampled 2017-06-26. Methodology: how these readings are compared.
What Lopez Lake is good for
From access and monitoring records, not editorial picks.
- Deep water145 ft surveyed max depth
Swimming conditions
No readingBacteria advisory
Nutrient and algae readings are not a swimming clearance. Lopez Lake is listed impaired under Clean Water Act §303(d) (IR 5) for biotoxins. Check local advisories before you swim.
Whether Lopez Lake is safe to swim in today is a call for the California State Water Resources Control Board and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Lopez Lake
These are the measurements SWRCB publishes for Lopez 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 615 µg/L.
| 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 | 615µg/L | Measured, not scored The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential. |
| Chlorophyll-a (algae) | No reading The green pigment in algae — a direct measure of how much algae is in the water. |
Ask about Lopez Lake
Answers come straight from the public measurements and survey records on this page.
Lake Details
Max depth
145 ft
Surface area
586 acres
Shoreline
14.1 mi
Stays via Stay22
Stays near Lopez Lake
Compare lakeside cabins, hotels, and vacation rentals near Lopez Lake in San Luis Obispo County, California — 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 Lopez 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.
Follow Lopez Lake’s readings
Email me when new measurements post for this lake. Updates stay free.
Or email
Fishing Lopez Lake
EPA Impairment Status
Lopez Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Designated uses not supporting: Drinking water, Recreation.
Source: EPA ATTAINS assessment unit CAL3103101419980804111704 · Official waterbody report
Nearby Lakes in San Luis Obispo County
Frequently asked questions about Lopez Lake
Where is Lopez Lake?
- Lopez Lake is a lake in San Luis Obispo County, California. Its water-quality measurements are published by SWRCB and shown on this page as reported.
What is the water quality of Lopez Lake?
- Lopez Lake in San Luis Obispo County, California has water-quality measurements published by SWRCB, shown here as reported. Phosphorus: 615 µg/L. Maximum depth: 145 ft. Surface area: 586 acres.
Is Lopez Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Lopez Lake is listed impaired under Clean Water Act §303(d) (IR 5) for biotoxins. Check local advisories before you swim.
How deep is Lopez Lake?
- Lopez Lake has a maximum depth of 145 feet. The lake covers 586 acres.
Explore Lopez Lake across LakeQuality
More lakes in California
Other Lakes in California
Where this data comes from
Measurements for Lopez Lake come from the EPA Water Quality Portal. Per-sample source details are not recorded for this lake.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database