Browns Lake
Woodbury County, IowaView mapDirections
Iowa DNR publishes the water-quality measurements for Browns Lake. Here is what has been measured.
- Hypereutrophic
- Impaired · Turbidity
- 28 ft max depth
- Public access
Browns Lake in Woodbury County, Iowa has water-quality measurements published by Iowa DNR, shown here as reported. Water clarity: 0.7 ft visibility. Phosphorus: 217 µg/L. Chlorophyll-a (algae): 61.6 µg/L.
Free interactive depth-contour map of Browns Lake, reaching a maximum surveyed depth of 10 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Iowa DNR.
Browns Lake is a highly nutrient-loaded hypereutrophic lake in Woodbury County, Iowa with an estimated average depth of about 28 feet. Overall water quality is improving over recent sampling years. Limited fish-species data available. Public access is available with 1 public boat landing. Compared to the 2 other monitored lakes in Woodbury County, Browns Lake ranks #3 for water quality.
Source: EPA Water Quality Portal sampling records, Iowa DNR, last sampled 2024-09-03. Methodology: how these readings are compared.
Browns Lake has one public boat landing. Vrbo is where to look for cabins and lake homes around Browns Lake, and Booking.com and Expedia search hotels near the lake for your dates.
What Browns Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
Swimming conditions
Readings onlyRecreation use not supported
Based on clarity and algae readings from past sampling — there is no live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Based on E. coli testing, Browns Lake never exceeded the EPA safe-swimming threshold (235 MPN/100mL) — on 0% of 8 samples across 2 seasons.
This is a historical summary of past testing, not a current condition — bacteria levels change quickly, especially after rain. Always check Iowa’s current beach and health-department advisories before swimming.
Whether Browns Lake is safe to swim in today is a call for the Iowa Department of Natural Resources and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Browns Lake
These are the measurements Iowa DNR publishes for Browns Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Very murky, less than 0.7 ft of visibility. Phosphorus 217 µg/L. Chlorophyll-a 61.6 µg/L. TSI 79.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 0.7ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 217µg/L | Measured, not scored The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential. |
| Chlorophyll-a (algae) | 61.6µg/L | Poor GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 79 | Hypereutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Very high nutrients, dense algae, poor clarity
Ask about Browns Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Browns Lake typically sits around 69°F at the surface in September. Summer average is about 78°F. Usually warmest in Jul (about 80°F) and coldest in May (about 64°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (64°F) to its warmest (80°F).
Typical surface water temperature by month, from 31 field readings (2010–2023) via the EPA Water Quality Portal. See the full Browns Lake water temperature breakdown →
Lake Details
Max depth
~28 ft est.
Public access
Yes
Listed by Iowa DNR
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Iowa has not published bathymetry for Browns Lake.
Lake Size & Watershed
Watershed (drainage) area
8 sq mi
HydroLAKES / HydroSHEDS
Surface area
153 acres
HydroLAKES / HydroSHEDS
Shoreline
4 mi
HydroLAKES / HydroSHEDS
Elevation
1,063 ft
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.
Recreation & Access
- Brown's Lake Wildlife AreaPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Stays via Stay22
Stays near Browns Lake
Compare lakeside cabins, hotels, and vacation rentals near Browns Lake in Woodbury County, Iowa — 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. The water-quality readings cover nutrients and algae, not lodging. Cabins and rentals around Browns Lake are listed below.
Top-rated places to stay near Browns Lake
Prices for Oct 23–25, 4 adults. Change dates on the map below.
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? Cabins and lodging at Browns Lake → · more Iowa lake trips
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Fishing Browns Lake
Water Quality Trend: Improving
Based on 4 years of monitoring (2021–2024).
Water clarity
Improving4 years
Phosphorus
Improving-60.6 µg/L/yr4 years
Chlorophyll-a
Improving-14.17 µg/L/yr4 years
EPA Impairment Status
Browns Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Designated uses not supporting: Recreation.
Source: EPA ATTAINS assessment unit IA 06-WEM-1735 · Official waterbody report
Regulated Pollution Sources Nearby
5 EPA-permitted facilities operate within about 5 miles of Browns Lake under Clean Water Act (NPDES) discharge permits, including 3 classified by the EPA as major dischargers. 3 facilities have a reported Clean Water Act violation in the past three years.
- Midamerican Energy - Neal North Energy CenterSergeant Bluff · 2.7 mi away · NPDES IA0004103MajorRecent violation
- Gelita Usa, Inc.Sergeant Bluff · 3.2 mi away · NPDES IA0004413MajorRecent violation
- Cf Industries Nitrogen, Llc - Port Neal Nitrogen ComplexSergeant Bluff · 3.2 mi away · NPDES IA0004014Major
- Ag Processing Inc. - Sergeant BluffSergeant Bluff · 1.7 mi away · NPDES IA0058815Recent violation
- Salix City Of StpSalix · 2.2 mi away · NPDES IA0032913
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.
Nearby Lakes in Woodbury County
Frequently asked questions about Browns Lake
Where is Browns Lake?
- Browns Lake is a lake in Woodbury County, Iowa. Its water-quality measurements are published by Iowa DNR and shown on this page as reported.
What is the water quality of Browns Lake?
- Browns Lake in Woodbury County, Iowa has water-quality measurements published by Iowa DNR, shown here as reported. Water clarity: 0.7 ft visibility. Phosphorus: 217 µg/L. Chlorophyll-a (algae): 61.6 µg/L.
Is Browns Lake safe to swim in?
- Based on E. coli testing, Browns Lake never exceeded the EPA safe-swimming threshold (235 MPN/100mL) — on 0% of 8 samples across 2 seasons. That is a historical summary of past bacteria testing, not a current reading and not a swimming clearance. Bacteria levels can spike quickly after heavy rain, so whether Browns Lake is safe to swim in today is a call for Iowa's water agency and the county health department; check their current beach advisories before you swim.
What is the water temperature of Browns Lake?
- Browns Lake typically sits around 69°F at the surface in September, from 31 EPA Water Quality Portal field readings (2010–2023). That is a typical value for the month, not a live reading.
How deep is Browns Lake?
- No published bathymetric survey covers Browns Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 28 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate.
Are there boat ramps on Browns Lake?
- Browns Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Brown's Lake Wildlife Area. Public access is listed as yes.
Can I fish at Browns Lake?
- Browns Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Seasons, size and bag limits, and whether you need a license are set by Iowa's fish and wildlife agency, so check its current regulations before you go.
Explore Browns Lake across LakeQuality
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Hypereutrophic Lakes in Iowa
Where this data comes from
46 measurements from 1 monitoring station, 2021–2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Iowa DNR Surface Water Monitoring Data
21IOWA_WQX46 samples · 2021–2024
Analytical methods
- Unknown
- Phosphorus by Colorimetry
- 445.0 ~ EPA; Chlorophyll and Pheophytin in Algae by Fluorescence
- In-Vitro Determination of Chlorophyll
- ISU modification of APHA 2130-B
Monitoring station identifiers (1)
EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from and data sources.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Lake size & watershed from HydroLAKES (HydroSHEDS)
Named boat-access points from the USGS National Boat Ramps inventory