Lake of the Hills
Scott County, Iowa657 acresView mapDirections
Iowa DNR publishes the water-quality measurements for Lake of the Hills. Here is what has been measured.
- Eutrophic
- Impaired · Algal growth
Lake of the Hills in Scott County, Iowa has water-quality measurements published by Iowa DNR, shown here as reported. Water clarity: 5.1 ft visibility. Phosphorus: 53 µg/L. Chlorophyll-a (algae): 16.8 µg/L. Surface area: 657 acres.
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.
Lake of the Hills is a 657-acre productive, nutrient-rich eutrophic lake in Scott County, Iowa. Overall water quality is improving over recent sampling years. Compared to the 4 other monitored lakes in Scott County, Lake of the Hills ranks #4 for water quality.
Source: EPA Water Quality Portal sampling records, Iowa DNR, last sampled 2024-08-26. Methodology: how these readings are compared.
Lake of the Hills covers about 660 acres in Scott County. Vrbo is where to look for cabins and lake homes around Lake of the Hills, and Booking.com and Expedia search hotels near the lake for your dates.
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. Lake of the Hills is listed impaired under Clean Water Act §303(d) (IR 4A) for algal growth. Check local advisories before you swim.
Whether Lake of the Hills 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 Lake of the Hills
These are the measurements Iowa DNR publishes for Lake of the Hills, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Murky, only visible to about 5.1 ft. Phosphorus 53 µg/L. Chlorophyll-a 16.8 µg/L. TSI 58.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 5.1ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 53µg/L | Fair GoodFairPoor |
| Chlorophyll-a (algae) | 16.8µg/L | Fair GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 58 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Lake of the Hills
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Lake of the Hills typically sits around 69°F at the surface in September. Summer average is about 79°F. Usually warmest in Jul (about 79°F) and coldest in Sep (about 69°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (69°F) to its warmest (79°F).
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 →
Lake Details
Surface area
657 acres
No bathymetric survey has been published for Lake of the Hills, so its depth is not documented here.
Stays via Stay22
Stays 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
Prices for Oct 30–Nov 1, 4 adults. Change dates on the map below.
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Planning a whole trip? See where to stay at Iowa’s top lakes →
Follow Lake of the Hills’s readings
Email me when new measurements post for this lake. Updates stay free.
Or email
Fishing Lake of the Hills
Water Quality Trend: Improving
Based on 4 years of monitoring (2020–2024).
Water clarity
Improving4 years
Phosphorus
Improving-41.11 µg/L/yr4 years
Chlorophyll-a
Improving-51.81 µg/L/yr4 years
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
Designated uses not supporting: Recreation.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit IA 01-NEM-68 · Official waterbody report
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.
Nearby Lakes in Scott County
Frequently asked questions about Lake of the Hills
Where is Lake of the Hills?
- Lake of the Hills is a lake in Scott County, Iowa. Its water-quality measurements are published by Iowa DNR and shown on this page as reported.
What is the water quality of Lake of the Hills?
- Lake of the Hills in Scott County, Iowa has water-quality measurements published by Iowa DNR, shown here as reported. Water clarity: 5.1 ft visibility. Phosphorus: 53 µg/L. Chlorophyll-a (algae): 16.8 µg/L. Surface area: 657 acres.
Is Lake of the Hills safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Lake of the Hills is listed impaired under Clean Water Act §303(d) (IR 4A) for algal growth. Check local advisories before you swim.
What is the water temperature of Lake of the Hills?
- Lake of the Hills typically sits around 69°F at the surface in September, from 26 EPA Water Quality Portal field readings (2010–2023). That is a typical value for the month, not a live reading.
Explore Lake of the Hills across LakeQuality
Depth, room, public access, and the state wake-sport rules
Species activity outlook by water temperature and season
Where to stay at Iowa's top lakes, each with its readings
Iowa's cleanest lakes, ranked on agency measurements
More lakes in Iowa
Other Lakes in Iowa
Eutrophic Lakes in Iowa
Where this data comes from
42 measurements from 1 monitoring station, 2022–2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Iowa DNR Surface Water Monitoring Data
21IOWA_WQX42 samples · 2022–2024
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)