Where is Oso Flaco Lake?

Oso Flaco 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.

Oso Flaco Lake

San Luis Obispo County, California40 acresView map Directions

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

Area

40 acres

Surface area

Shoreline

1.4 mi

Measured length

Impaired · Pesticides
Limited data

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Oso Flaco Lake in San Luis Obispo County, California has water-quality measurements published by SWRCB, shown here as reported. Surface area: 40 acres.

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Oso Flaco Lake is a 40-acre lake in San Luis Obispo County, California.

Source: EPA Water Quality Portal sampling records, your state environmental agency. Methodology: how these readings are compared.

Swimming conditions

No reading

Limited data

Nutrient and algae readings are not a swimming clearance. Oso Flaco Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for pesticides. Check local advisories before you swim.

Whether Oso Flaco 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.

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Water quality measurements for Oso Flaco Lake

These are the measurements SWRCB publishes for Oso Flaco 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.

Ask about Oso Flaco Lake

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

Lake Details

Surface area

40 acres

Shoreline

1.4 mi

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

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Stays near Oso Flaco Lake

Compare lakeside cabins, hotels, and vacation rentals near Oso Flaco 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.

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Fishing Oso Flaco Lake

→ Oso Flaco Lake fishing regulations (limits, seasons, special rules)

EPA Impairment Status

Oso Flaco Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).

Causes of impairment

Pesticides

Designated uses not supporting: Aquatic life, Fish consumption.

A Total Maximum Daily Load (TMDL) plan has been approved.

Source: EPA ATTAINS assessment unit CAL3121003020011121102545 · Official waterbody report

Nearby Lakes in San Luis Obispo County

White Lake2.6 miView →Lopez Reservoir11.1 miView →Lopez Lake14.3 miView →Laguna Lake16.7 miView →Twitchell Reservoir16.9 miView →Santa Margarita Lake22.3 miView →

Frequently asked questions about Oso Flaco Lake

Where is Oso Flaco Lake?: Oso Flaco 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 Oso Flaco Lake?: Oso Flaco Lake in San Luis Obispo County, California has water-quality measurements published by SWRCB, shown here as reported. Surface area: 40 acres.
Is Oso Flaco Lake safe to swim in?: Nutrient and algae readings are not a swimming clearance. Oso Flaco Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for pesticides. Check local advisories before you swim.