Smith Lake
Kossuth County, Iowa53 acresView mapDirections
Iowa DNR publishes the water-quality measurements for Smith Lake. Here is what has been measured.
- Hypereutrophic
- Impaired · Algal growth
- 35 ft max depth
- Public access
Smith Lake in Kossuth County, Iowa has water-quality measurements published by Iowa DNR, shown here as reported. Water clarity: 2.4 ft visibility. Phosphorus: 154.5 µg/L. Chlorophyll-a (algae): 39.1 µg/L. Surface area: 53 acres.
Free interactive depth-contour map of Smith Lake, reaching a maximum surveyed depth of 11 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Iowa DNR.
Smith Lake is a 53-acre highly nutrient-loaded hypereutrophic lake in Kossuth County, Iowa with an estimated average depth of about 35 feet. Water clarity is declining over recent sampling years. Limited fish-species data available. Public access is available.
Source: EPA Water Quality Portal sampling records, Iowa DNR, last sampled 2024-09-19. Methodology: how these readings are compared.
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. Smith Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for algal growth. Check local advisories before you swim.
Whether Smith 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 Smith Lake
These are the measurements Iowa DNR publishes for Smith 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 2.4 ft of visibility. Phosphorus 154.5 µg/L. Chlorophyll-a 39.1 µg/L. TSI 69.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 2.4ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 155µg/L | Poor GoodFairPoor |
| Chlorophyll-a (algae) | 39.1µg/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. | 69 | Hypereutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Very high nutrients, dense algae, poor clarity
Ask about Smith Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Smith Lake typically sits around 69°F at the surface in September. Summer average is about 75°F. Usually warmest in Jul (about 81°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 (81°F).
Typical surface water temperature by month, from 26 field readings (2010–2023) via the EPA Water Quality Portal. See the full Smith Lake water temperature breakdown →
Lake Details
Max depth
~35 ft est.
Surface area
53 acres
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 Smith Lake.
Lake Size & Watershed
Watershed (drainage) area
2 sq mi
HydroLAKES / HydroSHEDS
Shoreline
1.9 mi
HydroLAKES / HydroSHEDS
Elevation
1,155 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.
Stays via Stay22
Stays near Smith Lake
Compare lakeside cabins, hotels, and vacation rentals near Smith Lake in Kossuth 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 Smith Lake are listed below.
Top-rated places to stay near Smith Lake
Prices for Oct 23–25, 4 adults. Change dates on the map below.
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Planning a whole trip? See where to stay at Iowa’s top lakes →
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Fishing Smith Lake
Water Quality Trend: Stable
Based on 4 years of monitoring (2021–2024).
Water clarity
Worsening4 years
Phosphorus
Improving-57.8 µg/L/yr4 years
Chlorophyll-a
Stable+0.09 µg/L/yr4 years
Reservoir Info (USACE NID)
Smith Lake is a man-made reservoir impounded by the Lake Smith Dam (completed 1965), built primarily for recreation on the TR-BLACK CAT CREEK; earth-type dam, 21 ft tall and 570 ft long.
- Surface area
- 53 ac
- Normal storage
- 245 ac-ft
- Max storage
- 463 ac-ft
- Drainage area
- 1.8 sq mi
- Hazard class
- Significant
- Owner
- Kossuth County Conservation Board
Source: USACE National Inventory of Dams, NID ID IA00570 · Operator website
EPA Impairment Status
Smith 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 04-EDM-981 · Official waterbody report
Regulated Pollution Sources Nearby
5 EPA-permitted facilities operate within about 5 miles of Smith Lake under Clean Water Act (NPDES) discharge permits, including 1 classified by the EPA as major discharger. 4 facilities have a reported Clean Water Act violation in the past three years.
- Algona City Of StpAlgona · 4.1 mi away · NPDES IA0022055MajorRecent violation
- Oak Lake Maintenance, Inc.Algona · 3 mi away · NPDES IA0065242Recent violation
- Smithfield Hog Production DivisionAlgona · 4.2 mi away · NPDES IA0073784Recent violation
- Burt City Of StpBurt · 4.9 mi away · NPDES IA0027405Recent violation
- Ag Processing, Inc. - AlgonaAlgona · 3.4 mi away · NPDES IA0081116
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 Kossuth County
Frequently asked questions about Smith Lake
Where is Smith Lake?
- Smith Lake is a lake in Kossuth County, Iowa. Its water-quality measurements are published by Iowa DNR and shown on this page as reported.
What is the water quality of Smith Lake?
- Smith Lake in Kossuth County, Iowa has water-quality measurements published by Iowa DNR, shown here as reported. Water clarity: 2.4 ft visibility. Phosphorus: 154.5 µg/L. Chlorophyll-a (algae): 39.1 µg/L. Surface area: 53 acres.
Is Smith Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Smith Lake 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 Smith Lake?
- Smith Lake 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.
How deep is Smith Lake?
- No published bathymetric survey covers Smith Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 35 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 53 acres.
Can I fish at Smith Lake?
- Public access to Smith Lake is listed as yes on the lake record. 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 Smith Lake across LakeQuality
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Where this data comes from
49 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_WQX49 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)
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)