Cedar Lake
Linn County, Iowa115 acresView mapDirections
Nutrients and algae run well above the regional average.
- Hypereutrophic
- #2 of 2 in the county
- 39 ft max depth
- Public access
Cedar Lake in Linn County, Iowa has a water quality grade of F (Algae-prone). Water clarity: 0.9 ft visibility. Phosphorus: 256.5 µg/L. Chlorophyll-a (algae): 125.4 µg/L. Surface area: 115 acres.
- Clarity
- 0.9 ft
- Max depth
- ~39 ft est.
- Area
- 115 acres
- Type
- Hypereutrophic
- Trend
- ↓ Declining
- Public access
- Yes
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Stays near Cedar Lake
Compare lakeside cabins, hotels, and vacation rentals near Cedar Lake in Linn 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 Cedar Lake are listed below.
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Cedar Lake is a 115-acre highly nutrient-loaded hypereutrophic lake in Linn County, Iowa with an estimated average depth of about 39 feet. Water quality is graded F based on 2 sampling years through 2024. Overall water quality is declining over recent sampling years. Limited fish-species data available. Public access is available. Compared to the 1 other monitored lakes in Linn County, Cedar Lake ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, Iowa DNR, last sampled 2024-08-26. Grade methodology: LakeQuality methodology.
Swimming Safety
Grade onlyAlgae risk
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.
The F is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
Water Quality Grade: F (Algae-prone)
Very murky, less than 0.9 ft of visibility. Phosphorus 256.5 µg/L. Chlorophyll-a 125.4 µg/L. TSI 80. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 0.9 ft | Not graded |
| Phosphorus | 256.5 µg/L | Poor |
| Chlorophyll-a (Algae) | 125.4 µg/L | Poor |
| Trophic State Index (TSI) | 80 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~39 ft est. |
| Average Depth | ~9 ft est. |
| Surface Area | 115 acres |
| Public Access | Yes |
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Iowa has not published bathymetry for Cedar Lake.
Lake Size & Watershed
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.
Fishing Cedar Lake
Water Quality Trend: ↓ Declining
Based on 4 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.041 m/yr | 4 |
| Phosphorus | ↓ Declining | +47.9 µg/L/yr | 4 |
| Chlorophyll-a | ↓ Declining | +6.68 µg/L/yr | 4 |
Reservoir Info (USACE NID)
Cedar Lake is a man-made reservoir impounded by the Cedar Lake Dam, built primarily for flood risk reduction on the Tr to Cedar River; earth-type dam, 15 ft tall and 2,000 ft long.
- Surface area
- 115 ac
- Normal storage
- 200 ac-ft
- Max storage
- 1,350 ac-ft
- Drainage area
- 4.7 sq mi
- Hazard class
- Low
- Owner
- City of Cedar Rapids
Source: USACE National Inventory of Dams, NID ID IA04469 · Operator website
Regulated Pollution Sources Nearby
18 EPA-permitted facilities operate within about 5 miles of Cedar Lake under Clean Water Act (NPDES) discharge permits, including 1 classified by the EPA as major discharger. 3 facilities have a reported Clean Water Act violation in the past three years.
- Ipl - Prairie Creek Generating StationCedar Rapids · 3.5 mi away · NPDES IA0000540Major
- Cargill IncorporatedCedar Rapids · 1.9 mi away · NPDES IA0000647Recent violation
- Cedar Rapids Country ClubCedar Rapids · 2 mi away · NPDES IA0052651Recent violation
- Evergreen Packaging LlcCedar Rapids · 2.6 mi away · NPDES IA0003093Recent violation
- Ipl - Sixth Street Generating StationCedar Rapids · 0.5 mi away · NPDES IA0000132
- Quaker Manufacturing, LlcCedar Rapids · 0.7 mi away · NPDES IA0000761
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 Linn County
Nearby Lakes With Higher Grades
Cedar 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 Linn County
Frequently asked questions about Cedar Lake
Where is Cedar Lake?
- Cedar Lake is a lake in Linn County, Iowa. LakeQuality grades it F for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Cedar Lake?
- Cedar Lake in Linn County, Iowa has a water quality grade of F (Algae-prone). Water clarity: 0.9 ft visibility. Phosphorus: 256.5 µg/L. Chlorophyll-a (algae): 125.4 µg/L. Surface area: 115 acres.
Is Cedar Lake safe to swim in?
- The F is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
How deep is Cedar Lake?
- No published bathymetric survey covers Cedar Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 39 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate. The lake covers 115 acres.
Explore Cedar Lake across LakeQuality
More Iowa Lake Rankings
Other Grade F Lakes in Iowa
Hypereutrophic Lakes in Iowa
Where this data comes from
47 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_WQX47 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
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
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Lake size & watershed from HydroLAKES (HydroSHEDS)