Riverside County Lake Quality
California, 3 lakes, average grade D (Nutrient-rich)
Only 3 lakes in Riverside County carry an active grade. The county-level summary is therefore representative of those specific lakes, not necessarily of every water body in the county. The county-wide average grade is D — water quality issues are persistent across most of the monitored basins. 0 lakes fall into the F bracket outright.
Most of the county's monitored lakes are shallow — under 50 feet — which means wind keeps the water column mixed all summer and sediment-bound phosphorus releases back into the surface layer whenever the bottom is disturbed. Lake Morongo (D) is the cleanest in the county.
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Quick Answers for Riverside County
Planning a trip? Check special fishing regulations for Lake Morongo — or check the official California fishing regulations.
All Lakes in Riverside County
3 lakes · 1 graded, 2 not rated1 graded lake · 2 not rated, hidden
| # | Lake | Grade | Clarity | Phosphorus | Algae | Trophic | Access |
|---|---|---|---|---|---|---|---|
| 1 | DLake MorongoRiverside | D | No recent samples | 60 µg/L | No recent samples | No recent samples | Not recorded |
| NREagle Falls LakeRiverside | NR | No recent samples | 50 µg/L | No recent samples | No recent samples | Not recorded | |
| NRLake ElsinoreRiverside | NR | No recent samples | 330 µg/L | No recent samples | No recent samples | Not recorded |
NR = not rated: the monitoring record does not meet the evidence bar for a grade. That is EPA Integrated Reporting Category 3 (insufficient information), not a failing grade. How grading works.
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Other Counties in California
See how Riverside County stacks up in the national county water-quality rankings, or browse the full directory of graded lakes across all 49 states and 2 Canadian provinces.
Source: EPA National Aquatic Resource Surveys, 2026.