Brookfield Lake
Linn County, Missouri106 acresView mapDirections
Clarity, phosphorus, and algae all sit in the cleanest band for this region.
↑ up from B at the last regrade
- Mesotrophic
- #1 of 3 in the county
- 45 ft max depth
- Public access
Brookfield Lake in Linn County, Missouri has a water quality grade of A (Excellent). Water clarity: 4.4 ft visibility. Phosphorus: 19.7 µg/L. Chlorophyll-a (algae): 4.9 µg/L. Surface area: 106 acres.
- Clarity
- 4.4 ft
- Typical in September
- 76°F
- Max depth
- ~45 ft est.
- Area
- 106 acres
- Type
- Mesotrophic
- Trend
- → Stable
- Public access
- Yes
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Watch Brookfield Lake’s letter
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Brookfield Lake is a 106-acre mesotrophic lake in Linn County, Missouri with an estimated average depth of about 45 feet. Water quality is graded A based on 2 sampling years through 2024. Phosphorus level is declining over recent sampling years. Limited fish-species data available. Public access is available. Compared to the 2 other monitored lakes in Linn County, Brookfield Lake ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, Missouri DNR, last sampled 2024-08-07. Grade methodology: LakeQuality methodology.
Swimming Safety
Grade onlyLow algae
Based on clarity and algae grades from past sampling — we do not hold live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
The A is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
Water Quality Grade: A (Excellent)
Murky, only visible to about 4.4 ft. Phosphorus 19.7 µg/L. Chlorophyll-a 4.9 µg/L. TSI 50. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 4.4 ft | Not graded |
| Phosphorus | 19.7 µg/L | Good |
| Chlorophyll-a (Algae) | 4.9 µg/L | Good |
| Trophic State Index (TSI) | 50 | Mesotrophic |
Moderate nutrients, good water quality
Water Temperature
Brookfield Lake typically sits around 76°F at the surface in September. Summer average is about 81°F. Usually warmest in Jul (about 83°F) and coldest in May (about 70°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 60 field readings (2010–2024) via the EPA Water Quality Portal. See the full Brookfield Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~45 ft est. |
| Average Depth | ~12 ft est. |
| Surface Area | 106 acres |
| Public Access | Yes |
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Missouri has not published bathymetry for Brookfield Lake.
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth here is modelled, not surveyed — HydroLAKES v1.0 estimates lake depth from surrounding terrain rather than from soundings. Treat it as an approximation, and prefer a state bathymetric survey where one exists.
Fishing Brookfield Lake
Water Quality Trend: → Stable
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | +0.025 m/yr | 4 |
| Phosphorus | ↓ Declining | +1.52 µg/L/yr | 5 |
| Chlorophyll-a | ↑ Improving | -0.67 µg/L/yr | 5 |
Reservoir Info (USACE NID)
Brookfield Lake is a man-made reservoir impounded by the Brookfield Dam (completed 1959), built primarily for water supply on the TR WEST YELLOW CREEK; earth-type dam, 43 ft tall and 1,350 ft long.
- Surface area
- 106 ac
- Normal storage
- 1,365 ac-ft
- Max storage
- 1,775 ac-ft
- Drainage area
- 1.03 sq mi
- Hazard class
- High
All listed purposes: Water Supply;Recreation.
Source: USACE National Inventory of Dams, NID ID MO10181 · Operator website
Regulated Pollution Sources Nearby
9 EPA-permitted facilities operate within about 5 miles of Brookfield Lake under Clean Water Act (NPDES) discharge permits, including 1 classified by the EPA as major discharger. 1 facility has a reported Clean Water Act violation in the past three years.
- Brookfield WwtpBrookfield · 2.1 mi away · NPDES MO0137553Major
- Brookfield Country Club WwtfBrookfield · 0.7 mi away · NPDES MO0138339Recent violation
- Eastside Property Owners Assn WwtfBrookfield · 0.5 mi away · NPDES MO0122301
- Brookfield Country Club WwtfBrookfield · 0.7 mi away · NPDES MO0127469
- Brookfield Northeast WwtfBrookfield · 1.5 mi away · NPDES MO0028746
- Brookfield Swimming Pool WwtfBrookfield · 3.1 mi away · NPDES MO0046922
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.
County Ranking
Ranked #1 of 3 lakes in Linn County
Nearby Lakes in Linn County
Frequently asked questions about Brookfield Lake
Where is Brookfield Lake?
- Brookfield Lake is a lake in Linn County, Missouri. LakeQuality grades it A for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Brookfield Lake?
- Brookfield Lake in Linn County, Missouri has a water quality grade of A (Excellent). Water clarity: 4.4 ft visibility. Phosphorus: 19.7 µg/L. Chlorophyll-a (algae): 4.9 µg/L. Surface area: 106 acres.
Is Brookfield Lake safe to swim in?
- The A is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
What is the water temperature of Brookfield Lake?
- Brookfield Lake typically sits around 76°F at the surface in September, from 60 EPA Water Quality Portal field readings (2010–2024). That is a typical value for the month, not a live reading.
How deep is Brookfield Lake?
- No published bathymetric survey covers Brookfield Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 45 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate. The lake covers 106 acres.
Explore Brookfield Lake across LakeQuality
More Missouri Lake Rankings
Other Grade A Lakes in Missouri
Mesotrophic Lakes in Missouri
Where this data comes from
88 measurements from 1 monitoring station, 2020–2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Univ. of Missouri, Columbia
UMC88 samples · 2020–2024
Analytical methods
- Depth, Secchi disk in meters
- 4500 P E ~ Phosphorus in Water by Colorimetry- Ascorbic Acid Method
- 445.0 ~ EPA; Chlorophyll and Pheophytin in Algae by Fluorescence
Monitoring station identifiers (1)
Grade thresholds from the EPA National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See how grades are calculated and data sources.
Other records on this page
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Lake size & watershed from HydroLAKES (HydroSHEDS)