Smith Lake is a 53-acre productive, nutrient-rich eutrophic lake in Kossuth County, Iowa. 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 with 1 public boat landing.
Source: EPA Water Quality Portal sampling records, Iowa DNR, last sampled 2024-09-19. Grade methodology: LakeGrade methodology.
Watch Smith Lake water quality
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Swimming Safety
Avoid swimming, very poor water quality, potential algae toxins
Water Quality Grade: F, Very Poor
Very murky, less than 2.4 ft of visibility. Chlorophyll-a: 39.1 µg/L. Trophic State Index: 65.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 2.4 ft | F |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | 39.1 µg/L | F |
| Trophic State Index (TSI) | 65 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 53 acres |
| Public Access | Yes |
Where to stay near Smith Lake
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Fishing Smith Lake
Water Quality Trend: ↓ Declining
Based on 4 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.08 m/yr | 4 |
| Chlorophyll-a | → Stable | +0.09 µg/L/yr | 4 |
Recreation & Access
Water Temperature
Smith Lake averages about 75°F at the surface in summer, usually warmest in Jul (about 81°F) and coldest in Sep (about 69°F). These are typical values by month — not a live reading.
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 →
Location & Depth Map
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.
County Ranking
Ranked #1 of 1 lakes in Kossuth County
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Eutrophic Lakes in Iowa
More records, surveys & data sources
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
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit IA 04-EDM-981 · Official waterbody report
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth is a modeled estimate.
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.
Data Sources
Water quality data from the EPA Water Quality Portal
Impairment status from EPA ATTAINS 303(d) database
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Lake size & watershed from HydroLAKES (HydroSHEDS)
Grading methodology based on Metropolitan Council standards
Public boat-access points from the USGS National Boat Ramps inventory
Most recent sample: 2024-09-19
Monitoring stations: 1