Swan Lake Max Depth
Carroll County, Iowa130 acresView mapDirections
Nutrients and algae run well above the regional average.
- Hypereutrophic
- Impaired · Algal growth
- #1 of 1 in the county
- 41 ft max depth
Swan Lake Max Depth in Carroll County, Iowa has a water quality grade of F (Algae-prone). Water clarity: 1.4 ft visibility. Phosphorus: 433 µg/L. Chlorophyll-a (algae): 74 µg/L. Surface area: 130 acres.
- Clarity
- 1.4 ft
- Typical in August
- 76°F
- Max depth
- ~41 ft est.
- Area
- 130 acres
- Type
- Hypereutrophic
- Trend
- ↑ Improving
Stays via Stay22
Stays near Swan Lake Max Depth
Compare lakeside cabins, hotels, and vacation rentals near Swan Lake Max Depth in Carroll 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 Swan Lake Max Depth are listed below.
Top-rated places to stay near Swan Lake Max Depth
Prices for Sep 11–13, 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 →
Watch Swan Lake Max Depth’s letter
Email me if this lake’s grade moves. Grades stay free.
Or email
Free interactive depth-contour map of Swan Lake Max Depth, reaching a maximum surveyed depth of 10 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Iowa DNR.
Swan Lake Max Depth is a 130-acre highly nutrient-loaded hypereutrophic lake in Carroll County, Iowa with an estimated average depth of about 41 feet. Water quality is graded F based on 2 sampling years through 2024. Overall water quality is improving over recent sampling years.
Source: EPA Water Quality Portal sampling records, Iowa DNR, last sampled 2024-09-04. 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. Swan Lake Max Depth is listed impaired under Clean Water Act §303(d) (IR 4A) for algal growth, pH / acidity, turbidity. Check local advisories before you swim.
Water Quality Grade: F (Algae-prone)
Very murky, less than 1.4 ft of visibility. Phosphorus 433 µg/L. Chlorophyll-a 74 µg/L. TSI 79. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1.4 ft | Not graded |
| Phosphorus | 433 µg/L | Poor |
| Chlorophyll-a (Algae) | 74 µg/L | Poor |
| Trophic State Index (TSI) | 79 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Water Temperature
Swan Lake Max Depth typically sits around 76°F at the surface in August. Summer average is about 76°F. Usually warmest in Jul (about 79°F) and coldest in May (about 64°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 29 field readings (2010–2023) via the EPA Water Quality Portal. See the full Swan Lake Max Depth water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~41 ft est. |
| Average Depth | ~14 ft est. |
| Surface Area | 130 acres |
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Iowa has not published bathymetry for Swan Lake Max Depth.
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 Swan Lake Max Depth
Water Quality Trend: ↑ Improving
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.083 m/yr | 5 |
| Phosphorus | ↓ Declining | +56.15 µg/L/yr | 4 |
| Chlorophyll-a | ↑ Improving | -2.07 µg/L/yr | 5 |
Reservoir Info (USACE NID)
Swan Lake Max Depth is a man-made reservoir impounded by the Swan Lake Dam (completed 1935), built primarily for fish and wildlife pond on the Trib to Middle Raccoon; earth-type dam, 10 ft tall and 900 ft long.
- Surface area
- 130 ac
- Normal storage
- 440 ac-ft
- Max storage
- 600 ac-ft
- Drainage area
- 1.4 sq mi
- Hazard class
- Low
- Owner
- Iowa Department of Natural Resources
Source: USACE National Inventory of Dams, NID ID IA04222 · Operator website · Matched by proximity (0.46 km)
EPA Impairment Status
Swan Lake Max Depth 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 04-RAC-1199 · Official waterbody report · Matched by proximity (0.44 km)
County Ranking
Ranked #1 of 1 lakes in Carroll County
Nearby Lakes With Higher Grades
Swan Lake Max Depth 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 Carroll County
Frequently asked questions about Swan Lake Max Depth
Where is Swan Lake Max Depth?
- Swan Lake Max Depth is a lake in Carroll County, Iowa. LakeQuality grades it F for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Swan Lake Max Depth?
- Swan Lake Max Depth in Carroll County, Iowa has a water quality grade of F (Algae-prone). Water clarity: 1.4 ft visibility. Phosphorus: 433 µg/L. Chlorophyll-a (algae): 74 µg/L. Surface area: 130 acres.
Is Swan Lake Max Depth safe to swim in?
- The F is nutrients and algae, not a swimming clearance. Swan Lake Max Depth is listed impaired under Clean Water Act §303(d) (IR 4A) for algal growth, pH / acidity, turbidity. Check local advisories before you swim.
What is the water temperature of Swan Lake Max Depth?
- Swan Lake Max Depth typically sits around 76°F at the surface in August, 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 Swan Lake Max Depth?
- No published bathymetric survey covers Swan Lake Max Depth, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 41 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 130 acres.
Explore Swan Lake Max Depth across LakeQuality
More Iowa Lake Rankings
Other Grade F Lakes in Iowa
Hypereutrophic Lakes in Iowa
Where this data comes from
57 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_WQX57 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)
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
Impairment status from EPA ATTAINS 303(d) database
Lake size & watershed from HydroLAKES (HydroSHEDS)