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Lake Morongo

Riverside County, CaliforniaView mapDirections

SWRCB publishes the water-quality measurements for Lake Morongo. Here is what has been measured.

Phosphorus
60 µg/L
Typical for California
Measured by SWRCB
  • Limited data

Lake Morongo in Riverside County, California has water-quality measurements published by SWRCB, shown here as reported. Phosphorus: 60 µg/L.

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Lake Morongo is a lake in Riverside County, California.

Source: EPA Water Quality Portal sampling records, your state environmental agency, last sampled 2026-06-09. 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 Lake Morongo 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 Lake Morongo

These are the measurements SWRCB publishes for Lake Morongo, 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 60 µg/L. TSI 63.

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 phosphorus60µg/LMeasured, 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.

Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a.63Eutrophic
OligotrophicMesotrophicEutrophicHypereutrophic

High nutrients, frequent algae, reduced clarity

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Frequently asked questions about Lake Morongo

Where is Lake Morongo?

Lake Morongo is a lake in Riverside County, California. Its water-quality measurements are published by SWRCB and shown on this page as reported.

What is the water quality of Lake Morongo?

Lake Morongo in Riverside County, California has water-quality measurements published by SWRCB, shown here as reported. Phosphorus: 60 µg/L.

Measurements on this page ↑

Is Lake Morongo 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

68 measurements from 1 monitoring station, 2020–2026. Retrieved from the EPA Water Quality Portal on 2026-08-21.

Collected and reported by

  • Morongo Band of Mission IndiansMORONGO1_WQX68 samples · 2020–2026

Analytical methods

  • 4500 P B ~ Phosphorus, sample preparation method
  • 4500 P F ~ Phosphorus in Water by Colorimetry Automated Ascorbic Acid Method
  • Total Nitrogen by Calculation
  • 2130 B ~ Nephelometric Method
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.