Forest Lake is a 646-acre mesotrophic lake in Adair County, Missouri. Water quality is graded B based on 3 sampling years through 2024. Overall water quality is declining over recent sampling years. Compared to the 4 other monitored lakes in Adair County, Forest Lake ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, Missouri DNR, last sampled 2024-09-18. Grade methodology: LakeGrade methodology.
Watch Forest Lake water quality
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Swimming Safety
Good for swimming, clear water with low algae levels
Water Quality Grade: B, Good
Murky, only visible to about 4.1 ft. Phosphorus level: 18 µg/L. Chlorophyll-a: 4.8 µg/L. Trophic State Index: 50.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 4.1 ft | D |
| Phosphorus | 18 µg/L | A |
| Chlorophyll-a (Algae) | 4.8 µg/L | A |
| Trophic State Index (TSI) | 50 | Mesotrophic |
Moderate nutrients, good water quality
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 646 acres |
Where to stay near Forest Lake
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Fishing Forest Lake
Water Quality Trend: ↓ Declining
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | +0.011 m/yr | 5 |
| Phosphorus | → Stable | +0.24 µg/L/yr | 5 |
| Chlorophyll-a | ↓ Declining | +0.18 µg/L/yr | 5 |
Water Temperature
Forest Lake averages about 81°F at the surface in summer, usually warmest in Jul (about 83°F) and coldest in Apr (about 57°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 150 field readings (2010–2024) via the EPA Water Quality Portal. See the full Forest Lake water temperature breakdown →
Location
County Ranking
Ranked #1 of 5 lakes in Adair County
Nearby Lakes in Adair County
Explore Forest Lake across LakeGrade
More Missouri Lake Rankings
Other Grade B Lakes in Missouri
Mesotrophic Lakes in Missouri
Compare Forest Lake With Nearby Lakes
More records, surveys & data sources
Reservoir Info (USACE NID)
Forest Lake is a man-made reservoir impounded by the Forest Lake Dam (completed 1951), built primarily for recreation on the CHARITON RIVER; earth-type dam, 66 ft tall and 1,630 ft long.
- Surface area
- 646 ac
- Normal storage
- 12,431 ac-ft
- Max storage
- 15,961 ac-ft
- Drainage area
- 16.41 sq mi
- Hazard class
- High
- Owner
- CITY OF KIRKSVILLE
All listed purposes: Recreation;Water Supply.
Source: USACE National Inventory of Dams, NID ID MO10128 · Operator website
EPA Impairment Status
Forest 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 MO_7151.00 · Official waterbody report
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth is a modeled estimate.
Regulated Pollution Sources Nearby
2 EPA-permitted facilities operate within about 5 miles of Forest Lake under Clean Water Act (NPDES) discharge permits. 2 facilities have a reported Clean Water Act violation in the past three years.
- Novinger WwtfNovinger · 4.8 mi away · NPDES MO0056987Recent violation
- Spring Lake Sewer Company WwtpKirksville · 4.8 mi away · NPDES MO0129267Recent violation
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: 2024-09-18
Monitoring stations: 2