Rudd Lake
Floyd County, IowaView mapDirections
Iowa DNR publishes the water-quality measurements for Rudd Lake. Here is what has been measured.
- Mesotrophic
Rudd Lake in Floyd County, Iowa has water-quality measurements published by Iowa DNR, shown here as reported. Water clarity: 8.1 ft visibility. Phosphorus: 14 µg/L. Chlorophyll-a (algae): 4.5 µg/L.
Free interactive depth-contour map of Rudd Lake, reaching a maximum surveyed depth of 18 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Iowa DNR.
Rudd Lake is a mesotrophic lake in Floyd County, Iowa. Overall water quality is declining over recent sampling years.
Source: EPA Water Quality Portal sampling records, Iowa DNR, last sampled 2024-10-22. Methodology: how these readings are compared.
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Swimming conditions
Readings onlyLow algae
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. Check local advisories before you swim.
Whether Rudd 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 Rudd Lake
These are the measurements Iowa DNR publishes for Rudd Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Moderate clarity, visible to about 8.1 ft. Phosphorus 14 µg/L. Chlorophyll-a 4.5 µg/L. TSI 45.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 8.1ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 14µg/L | Good GoodFairPoor |
| Chlorophyll-a (algae) | 4.5µg/L | Good GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 45 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
Ask about Rudd Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Rudd Lake typically sits around 72°F at the surface in September. Summer average is about 77°F. Usually warmest in Jul (about 81°F) and coldest in Sep (about 72°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (72°F) to its warmest (81°F).
Typical surface water temperature by month, from 23 field readings (2011–2023) via the EPA Water Quality Portal. See the full Rudd Lake water temperature breakdown →
Stays via Stay22
Stays near Rudd Lake
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Fishing Rudd Lake
Water Quality Trend: Worsening
Based on 4 years of monitoring (2021–2024).
Water clarity
Worsening4 years
Phosphorus
Improving-2.7 µg/L/yr4 years
Chlorophyll-a
Worsening+2.49 µg/L/yr4 years
Regulated Pollution Sources Nearby
1 EPA-permitted facility operate within about 5 miles of Rudd Lake under Clean Water Act (NPDES) discharge permits. 1 facility has a reported Clean Water Act violation in the past three years.
- Rudd City Of StpRudd · 1.3 mi away · NPDES IA0061344Recent 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.
Nearby Lakes in Floyd County
Frequently asked questions about Rudd Lake
Where is Rudd Lake?
- Rudd Lake is a lake in Floyd County, Iowa. Its water-quality measurements are published by Iowa DNR and shown on this page as reported.
What is the water quality of Rudd Lake?
- Rudd Lake in Floyd County, Iowa has water-quality measurements published by Iowa DNR, shown here as reported. Water clarity: 8.1 ft visibility. Phosphorus: 14 µg/L. Chlorophyll-a (algae): 4.5 µg/L.
Is Rudd Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
What is the water temperature of Rudd Lake?
- Rudd Lake typically sits around 72°F at the surface in September, from 23 EPA Water Quality Portal field readings (2011–2023). That is a typical value for the month, not a live reading.
Explore Rudd Lake across LakeQuality
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Where this data comes from
66 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_WQX66 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
Regulated discharger data from EPA ECHO (ICIS-NPDES)