Timberline Lakes is a 42-acre cold, clear oligotrophic lake in St. Francois County, Missouri. Water quality is graded A based on 3 sampling years through 2024. Overall water quality is declining over recent sampling years. Compared to the 3 other monitored lakes in St. Francois County, Timberline Lakes ranks #3 for water quality.
Source: EPA Water Quality Portal sampling records, Missouri DNR, last sampled 2024-09-21. Grade methodology: LakeGrade methodology.
Watch Timberline Lakes water quality
Subscribe for LakeQuality updates by email. No spam, unsubscribe anytime.
Swimming Safety
Excellent for swimming, crystal clear water with minimal algae
Water Quality Grade: A, Excellent
Good clarity, visible to about 14.3 ft. Phosphorus level: 5.5 µg/L. Chlorophyll-a: 1.6 µg/L. Trophic State Index: 34.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 14.3 ft | B |
| Phosphorus | 5.5 µg/L | A |
| Chlorophyll-a (Algae) | 1.6 µg/L | A |
| Trophic State Index (TSI) | 34 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 42 acres |
Where to stay near Timberline Lakes
Compare lakeside cabins, hotels, and vacation rentals near Timberline Lakes in St. Francois 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.
Top-rated places to stay near Timberline Lakes
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Planning a trip to Timberline Lakes?
Get lake water-quality report cards plus the best cabin & lodging deals near Timberline Lakes — straight to your inbox. No spam, unsubscribe anytime.
Planning a whole trip? See where to stay at Missouri’s top lakes →
Fishing Timberline Lakes
Water Quality Trend: ↓ Declining
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.656 m/yr | 5 |
| Phosphorus | ↓ Declining | +0.45 µg/L/yr | 5 |
| Chlorophyll-a | ↑ Improving | -0.13 µg/L/yr | 5 |
Water Temperature
Timberline Lakes averages about 82°F at the surface in summer, usually warmest in Jul (about 84°F) and coldest in Apr (about 62°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 52 field readings (2010–2024) via the EPA Water Quality Portal. See the full Timberline Lakes water temperature breakdown →
Location
County Ranking
Ranked #3 of 4 lakes in St. Francois County
Nearby Lakes in St. Francois County
Explore Timberline Lakes across LakeGrade
Species activity outlook by water temperature and season
Where to stay at Missouri's top lakes, each with its grade
Low nutrients, clear water, excellent for swimming
Missouri's cleanest and most-polluted lakes, ranked
More Missouri Lake Rankings
Other Grade A Lakes in Missouri
Washington County · Clarity: 11.1 ft
Ste. Genevieve County · Clarity: 9.9 ft
Jefferson County · Clarity: 12.9 ft
Iron County · Clarity: 13.1 ft
Perry County · Clarity: 12 ft
Warren County · Clarity: 12.6 ft
Oligotrophic Lakes in Missouri
More records, surveys & data sources
Reservoir Info (USACE NID)
Timberline Lakes is a man-made reservoir impounded by the Lake Timberline Dam (completed 1963), built primarily for recreation on the BEE RUN CREEK; earth-type dam, 79 ft tall and 760 ft long.
- Surface area
- 42 ac
- Normal storage
- 1,083 ac-ft
- Max storage
- 1,464 ac-ft
- Drainage area
- 1.95 sq mi
- Hazard class
- High
- Owner
- LAKE TIMBERLINE BOARD OF TRUST
Source: USACE National Inventory of Dams, NID ID MO30156 · Operator website · Matched by proximity (0.06 km)
EPA Impairment Status
Timberline Lakes 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_7304.00 · Official waterbody report · Matched by proximity (0.47 km)
Regulated Pollution Sources Nearby
5 EPA-permitted facilities operate within about 5 miles of Timberline Lakes under Clean Water Act (NPDES) discharge permits. 3 facilities have a reported Clean Water Act violation in the past three years.
- Eagle Estates WwtpBonne Terre · 0.5 mi away · NPDES MO0120260Recent violation
- Stone Park ResortBonne Terre · 1.7 mi away · NPDES MO0137464Recent violation
- Bonne Terre Nw WwtpBonne Terre · 3.9 mi away · NPDES MO0100706Recent violation
- Boopers WwtfValles Mines · 2.4 mi away · NPDES MO0127388
- Bonne Terre Northeast WwtpBonne Terre · 4.8 mi away · NPDES MO0121321
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)
Grading methodology based on Metropolitan Council standards
Most recent sample: 2024-09-21
Monitoring stations: 1