Lake Cornelia
Wright County, IowaView mapDirections
Iowa DNR publishes the water-quality measurements for Lake Cornelia. Here is what has been measured.
- Eutrophic
- Impaired · Turbidity
- 53 ft max depth
- Public access
Lake Cornelia in Wright County, Iowa has water-quality measurements published by Iowa DNR, shown here as reported. Water clarity: 2.5 ft visibility. Phosphorus: 37 µg/L. Chlorophyll-a (algae): 20.1 µg/L.
Free interactive depth-contour map of Lake Cornelia, reaching a maximum surveyed depth of 20 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Iowa DNR.
Lake Cornelia is a productive, nutrient-rich eutrophic lake in Wright County, Iowa with an estimated average depth of about 53 feet. Overall water quality is improving over recent sampling years. Limited fish-species data available. Public access is available with 1 public boat landing.
Source: EPA Water Quality Portal sampling records, Iowa DNR, last sampled 2024-10-22. Methodology: how these readings are compared.
Lake Cornelia has one public boat landing. If you are planning to stay, you can search lake houses and cabins around Lake Cornelia on Vrbo, or look for a hotel room near the lake on Booking.com or Expedia.
What Lake Cornelia is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
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.
Based on E. coli testing, Lake Cornelia never exceeded the EPA safe-swimming threshold (235 MPN/100mL) — on 0% of 11 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 Lake Cornelia 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 Cornelia
These are the measurements Iowa DNR publishes for Lake Cornelia, 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 2.5 ft of visibility. Phosphorus 37 µg/L. Chlorophyll-a 20.1 µg/L. TSI 60.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 2.5ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 37µg/L | Good GoodFairPoor |
| Chlorophyll-a (algae) | 20.1µg/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. | 60 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Lake Cornelia
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Lake Cornelia typically sits around 71°F at the surface in September. Summer average is about 76°F. Usually warmest in Jul (about 81°F) and coldest in May (about 61°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (61°F) to its warmest (81°F).
Typical surface water temperature by month, from 29 field readings (2010–2023) via the EPA Water Quality Portal. See the full Lake Cornelia water temperature breakdown →
Lake Details
Max depth
~53 ft est.
Public access
Yes
Listed by Iowa DNR
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Iowa has not published bathymetry for Lake Cornelia.
Lake Size & Watershed
Watershed (drainage) area
1 sq mi
HydroLAKES / HydroSHEDS
Surface area
215 acres
HydroLAKES / HydroSHEDS
Shoreline
2.3 mi
HydroLAKES / HydroSHEDS
Elevation
1,191 ft
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth here is modelled, not surveyed — HydroLAKES v1.0 estimates lake depth from surrounding terrain rather than from soundings. Treat it as an approximation, and prefer a state bathymetric survey where one exists.
Recreation & Access
- Lake Cornelia State Management AreaPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Stays via Stay22
Stays near Lake Cornelia
Compare lakeside cabins, hotels, and vacation rentals near Lake Cornelia in Wright 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 Lake Cornelia are listed below.
Top-rated places to stay near Lake Cornelia
Prices for Oct 23–25, 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 Lake Cornelia → · more Iowa lake trips
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Fishing Lake Cornelia
Water Quality Trend: Improving
Based on 5 years of monitoring (2020–2024).
Water clarity
Improving5 years
Phosphorus
Improving-5.65 µg/L/yr4 years
Chlorophyll-a
Improving-1.78 µg/L/yr5 years
EPA Impairment Status
Lake Cornelia 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 04-UDM-1264 · Official waterbody report
Regulated Pollution Sources Nearby
1 EPA-permitted facility operate within about 5 miles of Lake Cornelia under Clean Water Act (NPDES) discharge permits. 1 facility has a reported Clean Water Act violation in the past three years.
- Lake Cornelia Sanitary DistrictClarion · 0.3 mi away · NPDES IA0066401Recent 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 Wright County
Frequently asked questions about Lake Cornelia
Where is Lake Cornelia?
- Lake Cornelia is a lake in Wright 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 Cornelia?
- Lake Cornelia in Wright County, Iowa has water-quality measurements published by Iowa DNR, shown here as reported. Water clarity: 2.5 ft visibility. Phosphorus: 37 µg/L. Chlorophyll-a (algae): 20.1 µg/L.
Is Lake Cornelia safe to swim in?
- Based on E. coli testing, Lake Cornelia never exceeded the EPA safe-swimming threshold (235 MPN/100mL) — on 0% of 11 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 Lake Cornelia 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 Lake Cornelia?
- Lake Cornelia typically sits around 71°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.
How deep is Lake Cornelia?
- No published bathymetric survey covers Lake Cornelia, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 53 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate.
Are there boat ramps on Lake Cornelia?
- Lake Cornelia has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Lake Cornelia State Management Area. Public access is listed as yes.
Can I fish at Lake Cornelia?
- Lake Cornelia 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 Lake Cornelia across LakeQuality
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Where this data comes from
77 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_WQX77 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)
Lake size & watershed from HydroLAKES (HydroSHEDS)
Named boat-access points from the USGS National Boat Ramps inventory