Briggs Woods Lake
Hamilton County, Iowa70 acresView mapDirections
Nutrients and algae run well above the regional average.
- Hypereutrophic
- Impaired · Algal growth
- #1 of 2 in the county
- 23 ft max depth
- Public access
Briggs Woods Lake in Hamilton County, Iowa has a water quality grade of F (Algae-prone). Water clarity: 1.5 ft visibility. Phosphorus: 87 µg/L. Chlorophyll-a (algae): 59.1 µg/L. Surface area: 70 acres.
- Clarity
- 1.5 ft
- Typical in September
- 73°F
- Max depth
- ~23 ft est.
- Area
- 70 acres
- Type
- Hypereutrophic
- Trend
- ↓ Declining
- Public access
- Yes
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Stays near Briggs Woods Lake
Compare lakeside cabins, hotels, and vacation rentals near Briggs Woods Lake in Hamilton 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 grade measures nutrients and algae, not lodging — cabins and rentals around Briggs Woods Lake are listed below.
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Watch Briggs Woods Lake’s letter
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Free interactive depth-contour map of Briggs Woods Lake, reaching a maximum surveyed depth of 26 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Iowa DNR.
Briggs Woods Lake is a 70-acre highly nutrient-loaded hypereutrophic lake in Hamilton County, Iowa with an estimated average depth of about 23 feet. Water quality is graded F based on 2 sampling years through 2024. Overall water quality is declining over recent sampling years. Limited fish-species data available. Public access is available with 2 public boat landings. Compared to the 1 other monitored lakes in Hamilton County, Briggs Woods Lake ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, Iowa DNR, last sampled 2024-10-30. Grade methodology: LakeQuality methodology.
What Briggs Woods Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch2 documented ramps
Swimming Safety
Grade onlyAlgae risk
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 F is nutrients and algae, not a swimming clearance. Briggs Woods Lake is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth, pH / acidity, turbidity. Check local advisories before you swim.
Water Quality Grade: F (Algae-prone)
Very murky, less than 1.5 ft of visibility. Phosphorus 87 µg/L. Chlorophyll-a 59.1 µg/L. TSI 70. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1.5 ft | Not graded |
| Phosphorus | 87 µg/L | Poor |
| Chlorophyll-a (Algae) | 59.1 µg/L | Poor |
| Trophic State Index (TSI) | 70 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Water Temperature
Briggs Woods Lake typically sits around 73°F at the surface in September. Summer average is about 77°F. Usually warmest in Jul (about 82°F) and coldest in May (about 61°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 32 field readings (2010–2023) via the EPA Water Quality Portal. See the full Briggs Woods Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~23 ft est. |
| Average Depth | ~10 ft est. |
| Surface Area | 70 acres |
| Public Access | Yes |
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Iowa has not published bathymetry for Briggs Woods 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.
Recreation & Access
- Briggs Wood ParkPublic
- Briggs Wood ParkPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fishing Briggs Woods Lake
Water Quality Trend: ↓ Declining
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.072 m/yr | 5 |
| Phosphorus | ↓ Declining | +1.9 µg/L/yr | 4 |
| Chlorophyll-a | ↓ Declining | +3.97 µg/L/yr | 5 |
Reservoir Info (USACE NID)
Briggs Woods Lake is a man-made reservoir impounded by the Briggs Woods Lake Dam (completed 1968), built primarily for recreation on the TR-BOONE RIVER; earth-type dam, 44 ft tall and 3,100 ft long.
- Surface area
- 70 ac
- Normal storage
- 1,310 ac-ft
- Max storage
- 2,100 ac-ft
- Drainage area
- 10.62 sq mi
- Hazard class
- Significant
- Owner
- Hamilton County Conservation Board
All listed purposes: Recreation;Water Supply.
Source: USACE National Inventory of Dams, NID ID IA00437 · Operator website
EPA Impairment Status
Briggs Woods Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit IA 04-UDM-1255 · Official waterbody report
Regulated Pollution Sources Nearby
3 EPA-permitted facilities operate within about 5 miles of Briggs Woods Lake under Clean Water Act (NPDES) discharge permits, including 1 classified by the EPA as major discharger. 3 facilities have a reported Clean Water Act violation in the past three years.
- Webster City, City Of StpWebster City · 1.8 mi away · NPDES IA0036625MajorRecent violation
- Webster City Municipal Bldg.Webster City · 2.7 mi away · NPDES IA0066281Recent violation
- Kamrar City Of StpKamrar · 4.7 mi away · NPDES IA0069124Recent 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.
County Ranking
Ranked #1 of 2 lakes in Hamilton County
Nearby Lakes With Higher Grades
Briggs Woods Lake holds Grade F. 2 nearby lakes hold higher nutrient-and-algae grades — useful for a swim day, not a reason to skip lodging here.
See full comparison →Nearby Lakes in Hamilton County
Frequently asked questions about Briggs Woods Lake
Where is Briggs Woods Lake?
- Briggs Woods Lake is a lake in Hamilton County, Iowa. LakeQuality grades it F for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Briggs Woods Lake?
- Briggs Woods Lake in Hamilton County, Iowa has a water quality grade of F (Algae-prone). Water clarity: 1.5 ft visibility. Phosphorus: 87 µg/L. Chlorophyll-a (algae): 59.1 µg/L. Surface area: 70 acres.
Is Briggs Woods Lake safe to swim in?
- The F is nutrients and algae, not a swimming clearance. Briggs Woods Lake is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth, pH / acidity, turbidity. Check local advisories before you swim.
What is the water temperature of Briggs Woods Lake?
- Briggs Woods Lake typically sits around 73°F at the surface in September, from 32 EPA Water Quality Portal field readings (2010–2023). That is a typical value for the month, not a live reading.
How deep is Briggs Woods Lake?
- No published bathymetric survey covers Briggs Woods Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 23 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 70 acres.
Are there boat ramps on Briggs Woods Lake?
- Briggs Woods Lake has 2 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Briggs Wood Park, Briggs Wood Park. Public access is listed as yes.
Explore Briggs Woods Lake across LakeQuality
More Iowa Lake Rankings
Other Grade F Lakes in Iowa
Hypereutrophic Lakes in Iowa
Where this data comes from
79 measurements from 1 monitoring station, 2020–2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Iowa DNR Surface Water Monitoring Data
21IOWA_WQX79 samples · 2020–2024
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)
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
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