Eldred Sherwood Lake
Hancock County, Iowa23 acresView mapDirections
Nutrients and algae run well above the regional average.
- Hypereutrophic
- Impaired · Pathogens (E. coli, fecal)
- #2 of 2 in the county
Eldred Sherwood Lake in Hancock County, Iowa has a water quality grade of F (Algae-prone). Water clarity: 3 ft visibility. Phosphorus: 89 µg/L. Chlorophyll-a (algae): 31.3 µg/L. Surface area: 23 acres.
- Clarity
- 3 ft
- Typical in September
- 71°F
- Area
- 23 acres
- Type
- Hypereutrophic
- Trend
- ↑ Improving
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Stays near Eldred Sherwood Lake
Compare lakeside cabins, hotels, and vacation rentals near Eldred Sherwood Lake in Hancock 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 Eldred Sherwood Lake are listed below.
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Watch Eldred Sherwood Lake’s letter
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Free interactive depth-contour map of Eldred Sherwood Lake, reaching a maximum surveyed depth of 21 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Iowa DNR.
Eldred Sherwood Lake is a 23-acre highly nutrient-loaded hypereutrophic lake in Hancock County, Iowa. Water quality is graded F based on 2 sampling years through 2024. Overall water quality is improving over recent sampling years. Compared to the 1 other monitored lakes in Hancock County, Eldred Sherwood Lake ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, Iowa DNR, last sampled 2024-10-28. Grade methodology: LakeQuality methodology.
Swimming Safety
Grade onlyBacteria A · advisory
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, Eldred Sherwood Lake never exceeded the EPA safe-swimming threshold (235 MPN/100mL) — on 0% of 21 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.
Water Quality Grade: F (Algae-prone)
Very murky, less than 3 ft of visibility. Phosphorus 89 µg/L. Chlorophyll-a 31.3 µg/L. TSI 65. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 3 ft | Not graded |
| Phosphorus | 89 µg/L | Poor |
| Chlorophyll-a (Algae) | 31.3 µg/L | Poor |
| Trophic State Index (TSI) | 65 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Water Temperature
Eldred Sherwood Lake typically sits around 71°F at the surface in September. Summer average is about 72°F. Usually warmest in Jul (about 76°F) and coldest in May (about 60°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 35 field readings (2010–2023) via the EPA Water Quality Portal. See the full Eldred Sherwood Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 23 acres |
No bathymetric survey has been published for Eldred Sherwood Lake, so its depth is not documented here.
Fishing Eldred Sherwood Lake
Water Quality Trend: ↑ Improving
Based on 4 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.153 m/yr | 4 |
| Phosphorus | ↑ Improving | -22.88 µg/L/yr | 4 |
| Chlorophyll-a | → Stable | +0.35 µg/L/yr | 4 |
Reservoir Info (USACE NID)
Eldred Sherwood Lake is a man-made reservoir impounded by the Eldred Sherwood Park Lake Dam (completed 1967), built primarily for other on the TR-EAST BRANCH IOWA RIVER; earth-type dam, 33 ft tall and 555 ft long.
- Surface area
- 23 ac
- Normal storage
- 220 ac-ft
- Max storage
- 360 ac-ft
- Drainage area
- 4.45 sq mi
- Hazard class
- Low
- Owner
- Hancock County Conservation Board
Source: USACE National Inventory of Dams, NID ID IA00438 · Operator website · Matched by proximity (0.05 km)
EPA Impairment Status
Eldred Sherwood 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 02-IOW-773 · Official waterbody report
Regulated Pollution Sources Nearby
2 EPA-permitted facilities operate within about 5 miles of Eldred Sherwood Lake under Clean Water Act (NPDES) discharge permits. 2 facilities have a reported Clean Water Act violation in the past three years.
- Goodell City Of StpGoodell · 2.5 mi away · NPDES IA0082562Recent violation
- Klemme City Of StpKlemme · 4.7 mi away · NPDES IA0038466Recent 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 #2 of 2 lakes in Hancock County
Nearby Lakes With Higher Grades
Eldred Sherwood Lake holds Grade F. 3 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 Hancock County
Frequently asked questions about Eldred Sherwood Lake
Where is Eldred Sherwood Lake?
- Eldred Sherwood Lake is a lake in Hancock County, Iowa. LakeQuality grades it F for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Eldred Sherwood Lake?
- Eldred Sherwood Lake in Hancock County, Iowa has a water quality grade of F (Algae-prone). Water clarity: 3 ft visibility. Phosphorus: 89 µg/L. Chlorophyll-a (algae): 31.3 µg/L. Surface area: 23 acres.
Is Eldred Sherwood Lake safe to swim in?
- Based on E. coli testing, Eldred Sherwood Lake never exceeded the EPA safe-swimming threshold (235 MPN/100mL) — on 0% of 21 samples across 2 seasons. That works out to a bacteria swim-safety grade of A — a historical summary of past testing, not a current reading. Eldred Sherwood 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 Eldred Sherwood Lake?
- Eldred Sherwood Lake typically sits around 71°F at the surface in September, from 35 EPA Water Quality Portal field readings (2010–2023). That is a typical value for the month, not a live reading.
Explore Eldred Sherwood Lake across LakeQuality
More Iowa Lake Rankings
Other Grade F Lakes in Iowa
Hypereutrophic Lakes in Iowa
Where this data comes from
82 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_WQX82 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
- 2130 B ~ Nephelometric Method
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)