Don Williams Lake
Boone County, Iowa160 acresView mapDirections
Nutrients and algae run well above the regional average.
- Hypereutrophic
- Impaired · Algal growth
- #1 of 1 in the county
- 40 ft max depth
- Public access
Don Williams Lake in Boone County, Iowa has a water quality grade of F (Algae-prone). Water clarity: 1.8 ft visibility. Phosphorus: 75 µg/L. Chlorophyll-a (algae): 45.2 µg/L. Surface area: 160 acres.
- Clarity
- 1.8 ft
- Typical in August
- 76°F
- Max depth
- ~40 ft est.
- Area
- 160 acres
- Type
- Hypereutrophic
- Phosphorus
- 75 µg/L
- Chlorophyll-a
- 45.2 µg/L
- Trend
- ↓ Declining
- Public access
- Yes
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Stays near Don Williams Lake
Compare lakeside cabins, hotels, and vacation rentals near Don Williams Lake in Boone 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 Don Williams Lake are listed below.
Top-rated places to stay near Don Williams Lake
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Free interactive depth-contour map of Don Williams Lake, reaching a maximum surveyed depth of 36 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Iowa DNR.
Don Williams Lake is a 160-acre highly nutrient-loaded hypereutrophic lake in Boone County, Iowa with an estimated average depth of about 40 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.
Source: EPA Water Quality Portal sampling records, Iowa DNR, last sampled 2024-09-04. Grade methodology: LakeQuality methodology.
Swimming Safety
Grade onlyBacteria D
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.
Based on E. coli testing, Don Williams Lake frequently exceeded the EPA safe-swimming threshold (235 MPN/100mL) — on 20% of 10 samples across 3 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.
Water Quality Grade: F (Algae-prone)
Very murky, less than 1.8 ft of visibility. Phosphorus 75 µg/L. Chlorophyll-a 45.2 µg/L. TSI 68. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1.8 ft | Not graded |
| Phosphorus | 75 µg/L | Poor |
| Chlorophyll-a (Algae) | 45.2 µg/L | Poor |
| Trophic State Index (TSI) | 68 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Water Temperature
Don Williams Lake typically sits around 76°F at the surface in August. Summer average is about 74°F. Usually warmest in Aug (about 76°F) and coldest in May (about 62°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 29 field readings (2010–2023) via the EPA Water Quality Portal. See the full Don Williams Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~40 ft est. |
| Average Depth | ~13 ft est. |
| Surface Area | 160 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 Don Williams 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 Don Williams Lake
Water Quality Trend: ↓ Declining
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | -0.005 m/yr | 5 |
| Phosphorus | ↓ Declining | +64.05 µg/L/yr | 4 |
| Chlorophyll-a | ↓ Declining | +4.72 µg/L/yr | 5 |
Reservoir Info (USACE NID)
Don Williams Lake is a man-made reservoir impounded by the Don Williams Lake Dam (completed 1965), built primarily for recreation on the BLUFF CREEK; earth-type dam, 58 ft tall and 600 ft long.
- Surface area
- 160 ac
- Normal storage
- 2,764 ac-ft
- Max storage
- 4,680 ac-ft
- Drainage area
- 33 sq mi
- Hazard class
- Significant
- Owner
- Boone County Conservation Board
Source: USACE National Inventory of Dams, NID ID IA00134 · Operator website
EPA Impairment Status
Don Williams Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit IA 04-UDM-1249 · Official waterbody report
Regulated Pollution Sources Nearby
4 EPA-permitted facilities operate within about 5 miles of Don Williams Lake under Clean Water Act (NPDES) discharge permits. 3 facilities have a reported Clean Water Act violation in the past three years.
- Pilot Mound City Of StpPilot Mound · 2.8 mi away · NPDES IA0058530Recent violation
- Northern Natural Gas Co. Ogden StationOgden · 4.7 mi away · NPDES IA0046957Recent violation
- Boone, City Of WtpBoone · 5 mi away · NPDES IA0079421Recent violation
- Ymca Camp Of BooneBoone · 4.4 mi away · NPDES IA0070874
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 1 lakes in Boone County
Nearby Lakes With Higher Grades
Don Williams Lake holds Grade F. One nearby lake has a higher nutrient-and-algae grade — useful for a swim day, not a reason to skip lodging here.
See full comparison →Nearby Lakes in Boone County
Frequently asked questions about Don Williams Lake
Where is Don Williams Lake?
- Don Williams Lake is a lake in Boone County, Iowa. LakeQuality grades it F for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Don Williams Lake?
- Don Williams Lake in Boone County, Iowa has a water quality grade of F (Algae-prone). Water clarity: 1.8 ft visibility. Phosphorus: 75 µg/L. Chlorophyll-a (algae): 45.2 µg/L. Surface area: 160 acres.
Is Don Williams Lake safe to swim in?
- Based on E. coli testing, Don Williams Lake frequently exceeded the EPA safe-swimming threshold (235 MPN/100mL) — on 20% of 10 samples across 3 seasons. That works out to a bacteria swim-safety grade of D — a historical summary of past testing, not a current reading. Don Williams Lake has a water quality grade of F (Algae-prone). Bacteria levels can spike quickly after heavy rain, so always check Iowa's current beach and health-department advisories before you swim.
What is the water temperature of Don Williams Lake?
- Don Williams Lake typically sits around 76°F at the surface in August, from 29 EPA Water Quality Portal field readings (2010–2023). That is a typical value for the month, not a live reading.
How deep is Don Williams Lake?
- No published bathymetric survey covers Don Williams Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 40 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 160 acres.
Explore Don Williams Lake across LakeQuality
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Where this data comes from
63 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_WQX63 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)