Lake Mariam
Lake Mariam in Polk County, Florida has a water quality grade of C (Fair). Water clarity: 1.6 ft visibility. Phosphorus: 52 µg/L.
- Clarity
- 1.6 ft
- Typical in September
- 92°F
- Type
- Eutrophic
- Trend
- ↓ Declining
- Public access
- Yes
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Lake Mariam is a productive, nutrient-rich eutrophic lake in Polk County, Florida. Water quality is graded C based on 1 sampling years through 2022. Overall water quality is declining over recent sampling years. Limited fish-species data available. Public access is available with 1 public boat landing. Compared to the 176 other monitored lakes in Polk County, Lake Mariam ranks #105 for water quality.
Source: EPA Water Quality Portal sampling records, FDEP, last sampled 2022-09-19. Grade methodology: LakeQuality methodology.
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Swimming Safety
Grade onlyLimited data
Based on clarity and algae grades from past sampling — we do not hold live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Generally safe for swimming, moderate water quality
Water Quality Grade: C (Fair)
Very murky, less than 1.6 ft of visibility. Phosphorus level: 52 µg/L. Trophic State Index: 66.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1.6 ft | Not graded |
| Phosphorus | 52 µg/L | Fair |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 66 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Lake Mariam
Compare lakeside cabins, hotels, and vacation rentals near Lake Mariam in Polk County, Florida — 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.
Top-rated places to stay near Lake Mariam
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Planning a trip? Cabins and lodging at Lake Mariam → · more Florida lake trips
Water Temperature
Lake Mariam typically sits around 92°F at the surface in September. Summer average is about 87°F. Usually warmest in Sep (about 92°F) and coldest in Dec (about 49°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 8 field readings (2010–2022) via the EPA Water Quality Portal. See the full Lake Mariam water temperature breakdown →
Recreation & Access
- Lake Mariam Public Boat RampPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fishing Lake Mariam
Water Quality Trend: ↓ Declining
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.07 m/yr | 6 |
| Phosphorus | → Stable | -0.27 µg/L/yr | 6 |
EPA Impairment Status
Lake Mariam is officially listed as impaired under Clean Water Act §303(d) in the 2022 EPA reporting cycle (IR category 5).
Causes of impairment
Source: EPA ATTAINS assessment unit FL1488P · Official waterbody report · Matched by proximity (2.84 km)
County Ranking
Ranked #105 of 177 lakes in Polk County
Nearby Lakes With Higher Grades
Lake Mariam holds Grade C. One nearby lake has a higher nutrient-and-algae grade — useful for a swim day, not a reason to skip lodging here.
Nearby Lakes in Polk County
Frequently asked questions about Lake Mariam
Where is Lake Mariam?
- Lake Mariam is a lake in Polk County, Florida. LakeQuality grades it C for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Lake Mariam?
- Lake Mariam in Polk County, Florida has a water quality grade of C (Fair). Water clarity: 1.6 ft visibility. Phosphorus: 52 µg/L.
Is Lake Mariam safe to swim in?
- Generally safe for swimming, moderate water quality. Lake Mariam has a water quality grade of C (Fair). Always check local health department advisories before swimming.
What is the water temperature of Lake Mariam?
- Lake Mariam typically sits around 92°F at the surface in September, from 8 EPA Water Quality Portal field readings (2010–2022). That is a typical value for the month, not a live reading.
Are there boat ramps on Lake Mariam?
- Lake Mariam has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Lake Mariam Public Boat Ramp. Public access is listed as yes.
Explore Lake Mariam across LakeQuality
More Florida Lake Rankings
Other Grade C Lakes in Florida
Eutrophic Lakes in Florida
Where this data comes from
12 measurements from 3 monitoring stations, 2020–2022. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Submitting organization not recorded for these samples10 samples · 2022
- Submitting organization not recorded for these samples2 samples · 2020
Monitoring station identifiers (3)
Grade thresholds from the EPA National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See how grades are calculated and data sources.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database
Named boat-access points from the USGS National Boat Ramps inventory