White Oak Lake
Mahaska County, Iowa20 acresView mapDirections
Iowa DNR publishes the water-quality measurements for White Oak Lake. Here is what has been measured.
- Hypereutrophic
- Impaired · Algal growth
- Public access
White Oak Lake in Mahaska County, Iowa has water-quality measurements published by Iowa DNR, shown here as reported. Water clarity: 1.4 ft visibility. Phosphorus: 125.5 µg/L. Chlorophyll-a (algae): 68.7 µg/L. Surface area: 20 acres.
Free interactive depth-contour map of White Oak Lake, reaching a maximum surveyed depth of 16 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Iowa DNR.
White Oak Lake is a 20-acre highly nutrient-loaded hypereutrophic lake in Mahaska County, Iowa. Overall water quality is declining over recent sampling years. Limited fish-species data available. Public access is available. Compared to the 2 other monitored lakes in Mahaska County, White Oak Lake ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, Iowa DNR, last sampled 2024-08-28. Methodology: how these readings are compared.
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.
Nutrient and algae readings are not a swimming clearance. White Oak Lake is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth, turbidity. Check local advisories before you swim.
Whether White Oak 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 White Oak Lake
These are the measurements Iowa DNR publishes for White Oak 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 1.4 ft of visibility. Phosphorus 125.5 µg/L. Chlorophyll-a 68.7 µg/L. TSI 73.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 1.4ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 126µg/L | Poor GoodFairPoor |
| Chlorophyll-a (algae) | 68.7µg/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. | 73 | Hypereutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Very high nutrients, dense algae, poor clarity
Ask about White Oak Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
White Oak Lake typically sits around 68°F at the surface in September. Summer average is about 78°F. Usually warmest in Aug (about 80°F) and coldest in Sep (about 68°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (68°F) to its warmest (80°F).
Typical surface water temperature by month, from 29 field readings (2010–2023) via the EPA Water Quality Portal. See the full White Oak Lake water temperature breakdown →
Lake Details
Surface area
20 acres
Public access
Yes
Listed by Iowa DNR
No bathymetric survey has been published for White Oak Lake, so its depth is not documented here.
Stays via Stay22
Stays near White Oak Lake
Compare lakeside cabins, hotels, and vacation rentals near White Oak Lake in Mahaska 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 White Oak Lake are listed below.
Top-rated places to stay near White Oak Lake
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Fishing White Oak Lake
Water Quality Trend: Worsening
Based on 5 years of monitoring (2020–2024).
Water clarity
Stable5 years
Phosphorus
Worsening+52.3 µg/L/yr4 years
Chlorophyll-a
Stable-0.17 µg/L/yr5 years
Reservoir Info (USACE NID)
White Oak Lake is a man-made reservoir impounded by the White Oak Lake Dam (completed 1983), built primarily for recreation on the TR- SNYDER CR.; earth-type dam, 39 ft tall and 555 ft long.
- Surface area
- 20 ac
- Normal storage
- 168 ac-ft
- Max storage
- 393 ac-ft
- Drainage area
- 0.94 sq mi
- Hazard class
- Significant
- Owner
- Mahaska County Conservation Board
Source: USACE National Inventory of Dams, NID ID IA02274 · Operator website
EPA Impairment Status
White Oak 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 03-SSK-929 · Official waterbody report
Regulated Pollution Sources Nearby
1 EPA-permitted facility operate within about 5 miles of White Oak Lake under Clean Water Act (NPDES) discharge permits. 1 facility has a reported Clean Water Act violation in the past three years.
- Rose Hill City Of StpRose Hill · 2.9 mi away · NPDES IA0072311Recent 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.
Nearby Lakes in Mahaska County
Frequently asked questions about White Oak Lake
Where is White Oak Lake?
- White Oak Lake is a lake in Mahaska County, Iowa. Its water-quality measurements are published by Iowa DNR and shown on this page as reported.
What is the water quality of White Oak Lake?
- White Oak Lake in Mahaska County, Iowa has water-quality measurements published by Iowa DNR, shown here as reported. Water clarity: 1.4 ft visibility. Phosphorus: 125.5 µg/L. Chlorophyll-a (algae): 68.7 µg/L. Surface area: 20 acres.
Is White Oak Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. White Oak Lake is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth, turbidity. Check local advisories before you swim.
What is the water temperature of White Oak Lake?
- White Oak Lake typically sits around 68°F at the surface in September, from 29 EPA Water Quality Portal field readings (2010–2023). That is a typical value for the month, not a live reading.
Can I fish at White Oak Lake?
- Public access to White Oak Lake is listed as yes on the lake record. 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 White Oak 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)
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)