Lake Grassy
Highlands County, FloridaView mapDirections
Florida DEP publishes the water-quality measurements for Lake Grassy. Here is what has been measured.
- Impaired · Mercury
- Limited data
Lake Grassy in Highlands County, Florida has water-quality measurements published by Florida DEP, shown here as reported. Water clarity: 4.3 ft visibility. Phosphorus: 9 µg/L.
Lake Grassy is a lake in Highlands County, Florida. Overall water quality is declining over recent sampling years.
Source: EPA Water Quality Portal sampling records, FDEP, last sampled 2025-03-11. Methodology: how these readings are compared.
Swimming conditions
No readingLimited data
Nutrient and algae readings are not a swimming clearance. Lake Grassy is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury. Check local advisories before you swim.
Whether Lake Grassy is safe to swim in today is a call for the Florida Department of Environmental Protection and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Lake Grassy
These are the measurements Florida DEP publishes for Lake Grassy, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Murky, only visible to about 4.3 ft. Phosphorus 9 µg/L. TSI 46.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 4.3ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 9µg/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. | |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 46 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
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Answers come straight from the public measurements and survey records on this page.
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Fishing Lake Grassy
Water Quality Trend: Worsening
Based on 5 years of monitoring (2021–2025).
Water clarity
Worsening5 years
Phosphorus
Worsening+0.5 µg/L/yr5 years
EPA Impairment Status
Lake Grassy is officially listed as impaired under Clean Water Act §303(d) in the 2022 EPA reporting cycle (IR category 4A).
Causes of impairment
Designated uses not supporting: Fish consumption.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit FL1932A · Official waterbody report
Nearby Lakes in Highlands County
Frequently asked questions about Lake Grassy
Where is Lake Grassy?
- Lake Grassy is a lake in Highlands County, Florida. Its water-quality measurements are published by Florida DEP and shown on this page as reported.
What is the water quality of Lake Grassy?
- Lake Grassy in Highlands County, Florida has water-quality measurements published by Florida DEP, shown here as reported. Water clarity: 4.3 ft visibility. Phosphorus: 9 µg/L.
Is Lake Grassy safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Lake Grassy is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury. Check local advisories before you swim.
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Where this data comes from
16 measurements from 2 monitoring stations, 2024–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Submitting organization not recorded for these samples10 samples · 2024
- Submitting organization not recorded for these samples6 samples · 2025
Monitoring station identifiers (2)
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.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database