Viking Lake is a 148-acre productive, nutrient-rich eutrophic lake in Montgomery County, Iowa. Water quality is graded F based on 2 sampling years through 2024. Overall water quality is improving over recent sampling years. Limited fish-species data available. Public access is available with 2 public boat landings.
Source: EPA Water Quality Portal sampling records, Iowa DNR, last sampled 2024-09-30. Grade methodology: LakeGrade methodology.
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Swimming Safety
Based on E. coli testing, Viking Lake frequently exceeded the EPA safe-swimming threshold (235 MPN/100mL) — on 10.9% of 101 samples across 7 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.
Water Quality Grade: F, Very Poor
Very murky, less than 3.3 ft of visibility. Chlorophyll-a: 32.7 µg/L. Trophic State Index: 62.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 3.3 ft | F |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | 32.7 µg/L | F |
| Trophic State Index (TSI) | 62 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 148 acres |
| Public Access | Yes |
Where to stay near Viking Lake
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Fishing Viking Lake
Water Quality Trend: ↑ Improving
Based on 4 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.027 m/yr | 4 |
| Chlorophyll-a | → Stable | +0.17 µg/L/yr | 4 |
Recreation & Access
Water Temperature
Viking Lake averages about 80°F at the surface in summer, usually warmest in Jul (about 83°F) and coldest in May (about 70°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 102 field readings (2010–2023) via the EPA Water Quality Portal. See the full Viking Lake water temperature breakdown →
Location & Depth Map
Free interactive depth-contour map of Viking Lake, reaching a maximum surveyed depth of 36 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Iowa DNR.
County Ranking
Ranked #1 of 1 lakes in Montgomery County
Cleaner Lakes Within 30 Miles
Viking Lake holds Grade F. 3 nearby lakes hold higher grades.
- CMormon Trail LakeAdair County · 27.6 mi · Two grade letters higher (F → C)
- DCold Springs LakeCass County · 22 mi · Higher grade (F → D)
- DBinder LakeAdams County · 16.8 mi · Higher grade (F → D)
Nearby Lakes in Montgomery County
Explore Viking Lake across LakeGrade
More Iowa Lake Rankings
Other Grade F Lakes in Iowa
Eutrophic Lakes in Iowa
More records, surveys & data sources
Reservoir Info (USACE NID)
Viking Lake is a man-made reservoir impounded by the Viking Lake Dam (completed 1957), built primarily for recreation on the DUNNS CREEK; earth-type dam, 69 ft tall and 1,220 ft long.
- Surface area
- 148 ac
- Normal storage
- 1,900 ac-ft
- Max storage
- 3,450 ac-ft
- Drainage area
- 3.42 sq mi
- Hazard class
- Significant
- Owner
- Iowa Department of Natural Resources
Source: USACE National Inventory of Dams, NID ID IA01366 · Operator website
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth is a modeled estimate.
Regulated Pollution Sources Nearby
3 EPA-permitted facilities operate within about 5 miles of Viking Lake under Clean Water Act (NPDES) discharge permits. 3 facilities have a reported Clean Water Act violation in the past three years.
- Dnr Viking Lake State ParkStanton · 1.1 mi away · NPDES IA0066036Recent violation
- Stanton City Of StpStanton · 4.3 mi away · NPDES IA0042978Recent violation
- Villisca City Of StpVillisca · 4.9 mi away · NPDES IA0032549Recent 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.
Data Sources
Water quality data from the EPA Water Quality Portal
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: 2024-09-30
Monitoring stations: 1