Smithville Lake
Clay County, WisconsinEutrophic
Smithville Lake is a 7,190-acre productive, nutrient-rich eutrophic lake in Clay County, MO. Water quality is graded D based on 3 sampling years through 2024. Compared to the 8 other monitored lakes in Clay County, Smithville Lake ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, local state DNR records, last sampled 2024-09-19. Grade methodology: LakeGrade methodology.
Swimming Safety
Swimming not recommended, poor water quality with high algae risk
Water Quality Grade: D, Poor
Very murky, less than 2.6 ft of visibility. Phosphorus level: 34 µg/L. Chlorophyll-a: 27.6 µg/L. Trophic State Index: 60.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 2.6 ft | F |
| Phosphorus | 34 µg/L | C |
| Chlorophyll-a (Algae) | 27.6 µg/L | D |
| Trophic State Index (TSI) | 60 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 7.2K acres |
Location
County Ranking
Ranked #2 of 9 lakes in Clay County
Cleaner Lakes Within 30 Miles
Smithville Lake holds Grade D. 2 nearby lakes hold higher grades.
- CWaukomis LakePlatte County · 13.6 mi · Higher grade (D → C)
- DWatkins Mill LakeClay County · 13.4 mi · Higher overall water quality score
Nearby Lakes in Clay County
More Wisconsin Lake Rankings
Other Grade D Lakes in Wisconsin
St. Louis city County · Clarity: 2.3 ft
Shelby County · Clarity: 3.2 ft
Macon County · Clarity: 1.8 ft
Harrison County · Clarity: 1.7 ft
Stone County · Clarity: 2.3 ft
Knox County · Clarity: 2.1 ft
Eutrophic Lakes in Wisconsin
Reservoir Info (USACE NID)
Smithville Lake is a man-made reservoir impounded by the Smithville Dam (completed 1979), built primarily for flood risk reduction on the LITTLE PLATTE RIVER; earth-type dam, 105 ft tall and 4,000 ft long.
- Surface area
- 7,190 ac
- Normal storage
- 144,600 ac-ft
- Max storage
- 246,500 ac-ft
- Drainage area
- 213 sq mi
- Hazard class
- High
- Owner
- USACE - Kansas City District
All listed purposes: Flood Risk Reduction;Other;Fish and Wildlife Pond;Recreation;Water Supply.
Source: USACE National Inventory of Dams, NID ID MO12084 · Operator website
Data Sources
Water quality data from the EPA Water Quality Portal
Grading methodology based on Metropolitan Council standards
Most recent sample: 2024-09-19
Monitoring stations: 1