Monroe City Lake B Nr. Dam is a 50-acre productive, nutrient-rich eutrophic lake in Monroe County, Missouri. Water quality is graded C based on 1 sampling years through 2025. Compared to the 2 other monitored lakes in Monroe County, Monroe City Lake B Nr. Dam ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, Missouri DNR, last sampled 2025-07-28. Grade methodology: LakeGrade methodology.
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Swimming Safety
Generally safe for swimming, moderate water quality
Water Quality Grade: C, Fair
No clarity data. Phosphorus level: 44 µg/L. Trophic State Index: 59.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No data | |
| Phosphorus | 44 µg/L | C |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 59 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 50 acres |
Where to stay near Monroe City Lake B Nr. Dam
Compare lakeside cabins, hotels, and vacation rentals near Monroe City Lake B Nr. Dam in Monroe County, Missouri — 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.
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Fishing Monroe City Lake B Nr. Dam
Invasive & Introduced Species
Red chips are ecologically harmful invasive species. Gray chips are stocked or introduced fish that aren't a current ecological concern.
Source: USGS Nonindigenous Aquatic Species (NAS) Database. Hover a chip to see scientific name, ecological context, status, and first-observed year.
Water Temperature
Monroe City Lake B Nr. Dam averages about 81°F at the surface in summer, usually warmest in Jul (about 83°F) and coldest in May (about 74°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 20 field readings (2012–2016) via the EPA Water Quality Portal. See the full Monroe City Lake B Nr. Dam water temperature breakdown →
Location
County Ranking
Ranked #1 of 3 lakes in Monroe County
Nearby Lakes in Monroe County
Explore Monroe City Lake B Nr. Dam across LakeGrade
More Missouri Lake Rankings
Other Grade C Lakes in Missouri
Eutrophic Lakes in Missouri
More records, surveys & data sources
Reservoir Info (USACE NID)
Monroe City Lake B Nr. Dam is a man-made reservoir impounded by the Monroe City South Lake Dam (completed 1937), built primarily for recreation on the TR.TO LITTLE INDIAN CREEK; earth-type dam, 31 ft tall.
- Surface area
- 50 ac
- Normal storage
- 217 ac-ft
- Max storage
- 829 ac-ft
- Drainage area
- 668 sq mi
- Hazard class
- High
- Owner
- CITY OF MONROE
All listed purposes: Recreation;Water Supply.
Source: USACE National Inventory of Dams, NID ID MO10538 · Operator website · Matched by proximity (0.06 km)
EPA Impairment Status
Monroe City Lake B Nr. Dam 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 MO_7034.00 · Official waterbody report · Matched by proximity (0.46 km)
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth is a modeled estimate.
Regulated Pollution Sources Nearby
5 EPA-permitted facilities operate within about 5 miles of Monroe City Lake B Nr. Dam under Clean Water Act (NPDES) discharge permits. 1 facility has a reported Clean Water Act violation in the past three years.
- Monroe City WwtpMonroe City · 1.9 mi away · NPDES MO0055379Recent violation
- Pace Industries - Monroe CityMonroe City · 1.9 mi away · NPDES MONX00395
- Lakeside Casting Solutions LlcMonroe City · 2.5 mi away · NPDES MONX00989
- Lakeside Technology Solutions LlcMonroe City · 3.5 mi away · NPDES MONX00987
- Paradise Lake Resort Aka Maple Creek SubMonroe City · 4.1 mi away · NPDES MO0123854
Facilities permitted to discharge under the Clean Water Act within ~5 miles; proximity does not by itself mean a facility affects this lake. Source: EPA ECHO (ICIS-NPDES), as of 2026-07.
Data Sources
Water quality data from the EPA Water Quality Portal
Impairment status from EPA ATTAINS 303(d) database
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Lake size & watershed from HydroLAKES (HydroSHEDS)
Grading methodology based on Metropolitan Council standards
Most recent sample: 2025-07-28
Monitoring stations: 1