Dems Lake
Sumter County, Alabama10,000 acresView mapDirections
Nutrients and algae sit mid-range for this region.
↓ down from B at the last regrade
- Eutrophic
- Impaired · Mercury
- #2 of 2 in the county
- Public access
Dems Lake in Sumter County, Alabama has a water quality grade of C (Fair). Water clarity: 2.7 ft visibility. Phosphorus: 24 µg/L. Chlorophyll-a (algae): 14.2 µg/L. Surface area: 10000 acres.
- Clarity
- 2.7 ft
- Area
- 10,000 acres
- Type
- Eutrophic
- Phosphorus
- 24 µg/L
- Chlorophyll-a
- 14.2 µg/L
- Trend
- ↓ Declining
- Public access
- Yes
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Watch Dems Lake’s letter
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Dems Lake is a 10,000-acre productive, nutrient-rich eutrophic lake in Sumter County, Alabama. Water quality is graded C based on 2 sampling years through 2025. Overall water quality is declining over recent sampling years. Limited fish-species data available. Public access is available with 4 public boat landings. Compared to the 1 other monitored lakes in Sumter County, Dems Lake ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, ADEM, last sampled 2025-10-27. Grade methodology: LakeQuality methodology.
What Dems Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch4 documented ramps
- Big water10,000 acres
Swimming Safety
Grade onlyModerate
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.
The C is nutrients and algae, not a swimming clearance. Dems Lake is listed impaired under Clean Water Act §303(d) (IR 5) for mercury. Check local advisories before you swim.
Water Quality Grade: C (Fair)
Very murky, less than 2.7 ft of visibility. Phosphorus 24 µg/L. Chlorophyll-a 14.2 µg/L. TSI 56. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 2.7 ft | Not graded |
| Phosphorus | 24 µg/L | Good |
| Chlorophyll-a (Algae) | 14.2 µg/L | Fair |
| Trophic State Index (TSI) | 56 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 10,000 acres |
| Public Access | Yes |
No bathymetric survey has been published for Dems Lake, so its depth is not documented here.
Recreation & Access
- BelmontPublic
- Foscue CreekPublic
- Demopolis City LandingPublic
- Lock No. 4Public
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fishing Dems Lake
Water Quality Trend: ↓ Declining
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.021 m/yr | 5 |
| Phosphorus | ↓ Declining | +0.8 µg/L/yr | 5 |
| Chlorophyll-a | ↓ Declining | +0.45 µg/L/yr | 5 |
Reservoir Info (USACE NID)
Dems Lake is a man-made reservoir impounded by the Demopolis Lock and Dam (completed 1955), built primarily for navigation on the Tombigbee River; gravity-type dam, 63 ft tall and 1,770 ft long.
- Surface area
- 10,000 ac
- Normal storage
- 120,000 ac-ft
- Max storage
- 150,000 ac-ft
- Drainage area
- 15,385 sq mi
- Hazard class
- Significant
- Owner
- USACE - Mobile District
All listed purposes: Navigation;Recreation.
Source: USACE National Inventory of Dams, NID ID AL01430 · Operator website · Matched by proximity (0.41 km)
EPA Impairment Status
Dems Lake 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 AL03160201-0401-102 · Official waterbody report · Matched by proximity (1.62 km)
County Ranking
Ranked #2 of 2 lakes in Sumter County
Nearby Lakes With Higher Grades
Dems Lake 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.
See full comparison →Nearby Lakes in Sumter County
Frequently asked questions about Dems Lake
Where is Dems Lake?
- Dems Lake is a lake in Sumter County, Alabama. LakeQuality grades it C for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Dems Lake?
- Dems Lake in Sumter County, Alabama has a water quality grade of C (Fair). Water clarity: 2.7 ft visibility. Phosphorus: 24 µg/L. Chlorophyll-a (algae): 14.2 µg/L. Surface area: 10000 acres.
Is Dems Lake safe to swim in?
- The C is nutrients and algae, not a swimming clearance. Dems Lake is listed impaired under Clean Water Act §303(d) (IR 5) for mercury. Check local advisories before you swim.
Are there boat ramps on Dems Lake?
- Dems Lake has 4 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Belmont, Foscue Creek, Demopolis City Landing, Lock No. 4. Public access is listed as yes.
Explore Dems Lake across LakeQuality
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Other Grade C Lakes in Alabama
Where this data comes from
129 measurements from 1 monitoring station, 2014–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- ALABAMA DEPT. OF ENVIRONMENTAL MANAGEMENT - WATER QUALITY DATA
21AWIC129 samples · 2014–2025
Analytical methods
- Phosphorus by Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
- 2120 B ~ Color in Water by Visual Comparison
Monitoring station identifiers (1)
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