Mark Twain Lake by Hwy J
Ralls County, WisconsinEutrophic
Mark Twain Lake by Hwy J is a 5,900-acre productive, nutrient-rich eutrophic lake in Ralls County, MO. Water quality is graded C based on 3 sampling years through 2024. Compared to the 3 other monitored lakes in Ralls County, Mark Twain Lake by Hwy J ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, local state DNR records, last sampled 2024-08-31. Grade methodology: LakeGrade methodology.
Swimming Safety
Generally safe for swimming, moderate water quality
Water Quality Grade: C, Fair
Murky, only visible to about 3.7 ft. Phosphorus level: 33.6 µg/L. Chlorophyll-a: 14.6 µg/L. Trophic State Index: 57.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 3.7 ft | D |
| Phosphorus | 33.6 µg/L | C |
| Chlorophyll-a (Algae) | 14.6 µg/L | C |
| Trophic State Index (TSI) | 57 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 5.9K acres |
Location
County Ranking
Ranked #1 of 4 lakes in Ralls County
Nearby Lakes in Ralls County
More Wisconsin Lake Rankings
Other Grade C Lakes in Wisconsin
Warren County · Clarity: 3.8 ft
Warren County · Clarity: 3.3 ft
Platte County · Clarity: 4.7 ft
Barry County · Clarity: 5 ft
Phelps County · Clarity: 4.9 ft
Randolph County · Clarity: 3.6 ft
Eutrophic Lakes in Wisconsin
Reservoir Info (USACE NID)
Mark Twain Lake by Hwy J is a man-made reservoir impounded by the Clarence Cannon Dam (completed 1983), built primarily for flood risk reduction on the SALT RIVER; concrete-type dam, 188 ft tall and 1,940 ft long.
- Surface area
- 5,900 ac
- Normal storage
- 520,661 ac-ft
- Max storage
- 1,862,000 ac-ft
- Drainage area
- 2,318 sq mi
- Hazard class
- High
- Owner
- USACE - St. Louis District
All listed purposes: Flood Risk Reduction;Navigation;Fish and Wildlife Pond;Recreation;Hydroelectric;Water Supply.
Source: USACE National Inventory of Dams, NID ID MO82201 · Operator website · Matched by proximity (0.51 km)
Data Sources
Water quality data from the EPA Water Quality Portal
Grading methodology based on Metropolitan Council standards
Most recent sample: 2024-08-31
Monitoring stations: 1