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LakeQuality

Rodeo Lagoon W Top Lake

Marin County, CaliforniaView mapDirections

SWRCB publishes the water-quality measurements for Rodeo Lagoon W Top Lake. Here is what has been measured.

Chlorophyll-a
66.7 µg/L
More algae than most
Measured by SWRCB
  • Limited data

Rodeo Lagoon W Top Lake in Marin County, California has water-quality measurements published by SWRCB, shown here as reported. Chlorophyll-a (algae): 66.7 µg/L.

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Rodeo Lagoon W Top Lake is a lake in Marin County, California.

Source: EPA Water Quality Portal sampling records, your state environmental agency, last sampled 2022-08-03. Methodology: how these readings are compared.

Swimming conditions

No reading

Limited data

Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.

Whether Rodeo Lagoon W Top 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 Rodeo Lagoon W Top Lake

These are the measurements SWRCB publishes for Rodeo Lagoon W Top 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. Chlorophyll-a 66.7 µg/L. TSI 72.

Water quality readings
MeasureReadingWhere it sits
Water clarity (Secchi depth)No reading

How deep a black-and-white disk stays visible from the surface. Higher is clearer.

Total phosphorusNo reading

The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential.

Chlorophyll-a (algae)66.7µg/LMeasured, not scored

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.72Hypereutrophic
OligotrophicMesotrophicEutrophicHypereutrophic

Very high nutrients, dense algae, poor clarity

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Frequently asked questions about Rodeo Lagoon W Top Lake

Where is Rodeo Lagoon W Top Lake?

Rodeo Lagoon W Top Lake is a lake in Marin County, California. Its water-quality measurements are published by SWRCB and shown on this page as reported.

What is the water quality of Rodeo Lagoon W Top Lake?

Rodeo Lagoon W Top Lake in Marin County, California has water-quality measurements published by SWRCB, shown here as reported. Chlorophyll-a (algae): 66.7 µg/L.

Measurements on this page ↑

Is Rodeo Lagoon W Top Lake safe to swim in?

Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.

Swimming on this page ↑

Where this data comes from

1 measurement from 1 monitoring station, 2022. Retrieved from the EPA Water Quality Portal on 2026-08-21.

Collected and reported by

  • USGS California Water Science CenterUSGS-CA1 sample · 2022

Analytical methods

  • Plant pigments, sonication & 445
Monitoring station identifiers (1)

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.