Clear Lake
Cerro Gordo County, IowaView mapDirections
Iowa DNR publishes the water-quality measurements for Clear Lake. Here is what has been measured.
- Eutrophic
- Impaired · Pathogens (E. coli, fecal)
- Public access
Clear Lake in Cerro Gordo County, Iowa has water-quality measurements published by Iowa DNR, shown here as reported. Water clarity: 2.1 ft visibility. Phosphorus: 52 µg/L. Chlorophyll-a (algae): 26.4 µg/L.
Free interactive depth-contour map of Clear Lake, reaching a maximum surveyed depth of 22 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Iowa DNR.
Clear Lake is a productive, nutrient-rich eutrophic lake in Cerro Gordo County, Iowa. Overall water quality is improving over recent sampling years. Limited fish-species data available. Public access is available with 1 public boat landing. Compared to the 3 other monitored lakes in Cerro Gordo County, Clear Lake ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, Iowa DNR, last sampled 2024-10-22. Methodology: how these readings are compared.
Clear Lake has one public boat landing. For a place on the water, look through cabin and lake-house rentals near Clear Lake on Vrbo. For a hotel or motel room, Booking.com and Expedia both search around the lake.
What Clear Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
Clear Lake Water Quality Summary (2026)
A printable one-page summary for Clear Lake: clarity, phosphorus, algae, multi-year trend, depth, and fish — with sources.
Swimming conditions
Readings onlyBacteria advisory
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.
Based on E. coli testing, Clear Lake never exceeded the EPA safe-swimming threshold (235 MPN/100mL) — on 0% of 8 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.
Whether Clear 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 Clear Lake
These are the measurements Iowa DNR publishes for Clear 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 2.1 ft of visibility. Phosphorus 52 µg/L. Chlorophyll-a 26.4 µg/L. TSI 63.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 2.1ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 52µg/L | Fair GoodFairPoor |
| Chlorophyll-a (algae) | 26.4µg/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. | 63 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Clear Lake
Answers come straight from the public measurements and survey records on this page.
Current Conditions
USGS snapshot Jul 6, 2026, 5:00 AM from gauge 05460000 (Clear Lake at Clear Lake, IA). Station page ↗ — a live reading replaces this snapshot when the gauge responds. Missing live data is not an all-clear.
Water Temperature
Clear Lake typically sits around 70°F at the surface in September. Summer average is about 75°F. Usually warmest in Jul (about 80°F) and coldest in May (about 59°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (59°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 Clear Lake water temperature breakdown →
Recreation & Access
- Nelson StreetPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Stays via Stay22
Stays near Clear Lake
Compare lakeside cabins, hotels, and vacation rentals near Clear Lake in Cerro Gordo 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 Clear Lake are listed below.
Top-rated places to stay near Clear Lake
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 trip? Cabins and lodging at Clear Lake → · more Iowa lake trips
Follow Clear Lake’s readings
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Fishing Clear Lake
Water Quality Trend: Improving
Based on 5 years of monitoring (2020–2024).
Water clarity
Worsening5 years
Phosphorus
Improving-6.85 µg/L/yr4 years
Chlorophyll-a
Improving-1.46 µg/L/yr5 years
EPA Impairment Status
Clear Lake 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 02-WIN-841 · Official waterbody report
Regulated Pollution Sources Nearby
3 EPA-permitted facilities operate within about 5 miles of Clear Lake under Clean Water Act (NPDES) discharge permits, including 1 classified by the EPA as major discharger. 2 facilities have a reported Clean Water Act violation in the past three years.
- Clear Lake Sanitary DistrictClear Lake · 1.5 mi away · NPDES IA0058441MajorRecent violation
- Randy'S Neighborhood MarketClear Lake · 2 mi away · NPDES IA0081108Recent violation
- Magellan Pipeline Company, LpClear Lake · 3.3 mi away · NPDES IA0074411
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 Cerro Gordo County
Frequently asked questions about Clear Lake
Where is Clear Lake?
- Clear Lake is a lake in Cerro Gordo County, Iowa. Its water-quality measurements are published by Iowa DNR and shown on this page as reported.
What is the water quality of Clear Lake?
- Clear Lake in Cerro Gordo County, Iowa has water-quality measurements published by Iowa DNR, shown here as reported. Water clarity: 2.1 ft visibility. Phosphorus: 52 µg/L. Chlorophyll-a (algae): 26.4 µg/L.
Is Clear Lake safe to swim in?
- Based on E. coli testing, Clear Lake never exceeded the EPA safe-swimming threshold (235 MPN/100mL) — on 0% of 8 samples across 3 seasons. That is a historical summary of past bacteria testing, not a current reading and not a swimming clearance. Bacteria levels can spike quickly after heavy rain, so whether Clear Lake is safe to swim in today is a call for Iowa's water agency and the county health department; check their current beach advisories before you swim.
What is the water temperature of Clear Lake?
- Clear Lake typically sits around 70°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.
What is the water level at Clear Lake?
- The USGS snapshot on this page for Clear Lake is 5.1 ft of gage height, recorded Jul 6, 2026, 5:00 AM at gauge 05460000. Current Conditions hydrates a live NWIS reading from that same station when the gauge responds. A missed live fetch is not an all-clear.
Are there boat ramps on Clear Lake?
- Clear Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Nelson Street. Public access is listed as yes.
Can I fish at Clear Lake?
- Clear Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. 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 Clear Lake across LakeQuality
More lakes in Iowa
Other Lakes in Iowa
Eutrophic Lakes in Iowa
Where this data comes from
75 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_WQX75 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)
Named boat-access points from the USGS National Boat Ramps inventory