Lake of the Hills is a 657-acre productive, nutrient-rich eutrophic lake in Scott County, Iowa. Water quality is graded C based on 2 sampling years through 2024. Overall water quality is improving over recent sampling years. Compared to the 4 other monitored lakes in Scott County, Lake of the Hills ranks #5 for water quality.
Source: EPA Water Quality Portal sampling records, Iowa DNR, last sampled 2024-08-26. Grade methodology: LakeGrade methodology.
Watch Lake of the Hills water quality
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Swimming Safety
Swim with caution, moderate algae may be present
Water Quality Grade: C, Fair
Murky, only visible to about 5.1 ft. Chlorophyll-a: 16.8 µg/L. Trophic State Index: 56.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 5.1 ft | D |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | 16.8 µg/L | C |
| Trophic State Index (TSI) | 56 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 657 acres |
Where to stay near Lake of the Hills
Compare lakeside cabins, hotels, and vacation rentals near Lake of the Hills in Scott 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.
Top-rated places to stay near Lake of the Hills
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Fishing Lake of the Hills
Water Quality Trend: ↑ Improving
Based on 4 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.415 m/yr | 4 |
| Chlorophyll-a | ↑ Improving | -51.81 µg/L/yr | 4 |
Water Temperature
Lake of the Hills averages about 79°F at the surface in summer, usually warmest in Jul (about 79°F) and coldest in Sep (about 69°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 26 field readings (2010–2023) via the EPA Water Quality Portal. See the full Lake of the Hills water temperature breakdown →
Location & Depth Map
Free interactive depth-contour map of Lake of the Hills, reaching a maximum surveyed depth of 20 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Iowa DNR.
County Ranking
Ranked #5 of 5 lakes in Scott County
Cleaner Lakes Within 30 Miles
Lake of the Hills holds Grade C. 2 nearby lakes hold higher grades.
- BLambach LakeScott County · 0.3 mi · Higher grade (C → B)
- CRailroad LakeScott County · 0.4 mi · Higher overall water quality score
Nearby Lakes in Scott County
Explore Lake of the Hills across LakeGrade
More Iowa Lake Rankings
Other Grade C Lakes in Iowa
Eutrophic Lakes in Iowa
More records, surveys & data sources
Reservoir Info (USACE NID)
Lake of the Hills is a man-made reservoir impounded by the Lake of The Hills Dam (completed 1972), built primarily for other on the BLACKHAWK CREEK; earth-type dam, 48 ft tall and 2,400 ft long.
- Surface area
- 657 ac
- Normal storage
- 613 ac-ft
- Max storage
- 1,950 ac-ft
- Drainage area
- 2.6 sq mi
- Hazard class
- High
- Owner
- Iowa Department of Transportation,SCOTT COUNTY CONSERVATION
All listed purposes: Other;Recreation.
Source: USACE National Inventory of Dams, NID ID IA00978 · Operator website
EPA Impairment Status
Lake of the Hills 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 01-NEM-68 · Official waterbody report
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth is a modeled estimate.
Regulated Pollution Sources Nearby
12 EPA-permitted facilities operate within about 5 miles of Lake of the Hills under Clean Water Act (NPDES) discharge permits, including 2 classified by the EPA as major dischargers. 9 facilities have a reported Clean Water Act violation in the past three years.
- Davenport City Of StpDavenport · 3.2 mi away · NPDES IA0043052MajorRecent violation
- Rock Island Main Stp, City OfRock Island · 4.4 mi away · NPDES IL0030783MajorRecent violation
- West Lake ParkDavenport · 0.3 mi away · NPDES IA0066974Recent violation
- Lakeside Manor Mobile Home CommunityDavenport · 1.3 mi away · NPDES IA0064718Recent violation
- Davenport Estates MhcDavenport · 3.2 mi away · NPDES IA0063339Recent violation
- Texpar Energy, LlcDavenport · 3.9 mi away · NPDES IA0001180Recent 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.
Data Sources
Water quality data from the EPA Water Quality Portal
Impairment status from EPA ATTAINS 303(d) database
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Lake size & watershed from HydroLAKES (HydroSHEDS)
Grading methodology based on Metropolitan Council standards
Most recent sample: 2024-08-26
Monitoring stations: 1