Lake Geode
Des Moines County, Iowa195 acresView mapDirections
Nutrients and algae run well above the regional average.
- Hypereutrophic
- Impaired · Mercury
- #2 of 2 in the county
- Public access
Lake Geode in Des Moines County, Iowa has a water quality grade of F (Algae-prone). Water clarity: 2.1 ft visibility. Phosphorus: 53.5 µg/L. Chlorophyll-a (algae): 30.5 µg/L. Surface area: 195 acres.
- Clarity
- 2.1 ft
- Typical in September
- 73°F
- Area
- 195 acres
- Type
- Hypereutrophic
- Trend
- → Stable
- Public access
- Yes
Stays via Stay22
Stays near Lake Geode
Compare lakeside cabins, hotels, and vacation rentals near Lake Geode in Des Moines 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 Lake Geode are listed below.
Top-rated places to stay near Lake Geode
Prices for Sep 11–13, 4 adults. Change dates on the map below.
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Watch Lake Geode’s letter
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Lake Geode is a 195-acre highly nutrient-loaded hypereutrophic lake in Des Moines County, Iowa. Water quality is graded F based on 2 sampling years through 2024. Phosphorus level is improving over recent sampling years. Limited fish-species data available. Public access is available. Compared to the 1 other monitored lakes in Des Moines County, Lake Geode ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, Iowa DNR, last sampled 2024-09-16. Grade methodology: LakeQuality methodology.
Swimming Safety
Grade onlyBacteria advisory
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. Lake Geode is listed impaired under Clean Water Act §303(d) (IR 5) for mercury, pathogens (E. coli, fecal), pH / acidity. Check local advisories before you swim.
Water Quality Grade: F (Algae-prone)
Very murky, less than 2.1 ft of visibility. Phosphorus 53.5 µg/L. Chlorophyll-a 30.5 µg/L. TSI 64. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 2.1 ft | Not graded |
| Phosphorus | 53.5 µg/L | Fair |
| Chlorophyll-a (Algae) | 30.5 µg/L | Poor |
| Trophic State Index (TSI) | 64 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Water Temperature
Lake Geode typically sits around 73°F at the surface in September. Summer average is about 78°F. Usually warmest in Jul (about 81°F) and coldest in May (about 71°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 23 field readings (2010–2023) via the EPA Water Quality Portal. See the full Lake Geode water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 195 acres |
| Public Access | Yes |
No bathymetric survey has been published for Lake Geode, so its depth is not documented here.
Fishing Lake Geode
Water Quality Trend: → Stable
Based on 4 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | -0.012 m/yr | 4 |
| Phosphorus | ↑ Improving | -11.85 µg/L/yr | 4 |
| Chlorophyll-a | ↓ Declining | +10.4 µg/L/yr | 4 |
Reservoir Info (USACE NID)
Lake Geode is a man-made reservoir impounded by the Geode Lake Dam (completed 1949), built primarily for recreation on the TR-SKUNK RIVER; earth-type dam, 59 ft tall and 1,060 ft long.
- Surface area
- 195 ac
- Normal storage
- 4,700 ac-ft
- Max storage
- 6,200 ac-ft
- Drainage area
- 15.35 sq mi
- Hazard class
- Significant
- Owner
- Iowa Department of Natural Resources
Source: USACE National Inventory of Dams, NID ID IA01347 · Operator website
EPA Impairment Status
Lake Geode is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit IA 03-SKU-896 · Official waterbody report
Regulated Pollution Sources Nearby
3 EPA-permitted facilities operate within about 5 miles of Lake Geode under Clean Water Act (NPDES) discharge permits. 2 facilities have a reported Clean Water Act violation in the past three years.
- Dnr Geode State ParkDanville · 0.8 mi away · NPDES IA0052732Recent violation
- Danville City Of StpDanville · 4.8 mi away · NPDES IA0025861Recent violation
- Dnr Geode State ParkDanville · 0.8 mi away · NPDES IA0066061
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.
County Ranking
Ranked #2 of 2 lakes in Des Moines County
Nearby Lakes With Higher Grades
Lake Geode holds Grade F. One nearby lake has a higher nutrient-and-algae grade — useful for a swim day, not a reason to skip lodging here.
See full comparison →Nearby Lakes in Des Moines County
Frequently asked questions about Lake Geode
Where is Lake Geode?
- Lake Geode is a lake in Des Moines County, Iowa. LakeQuality grades it F for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Lake Geode?
- Lake Geode in Des Moines County, Iowa has a water quality grade of F (Algae-prone). Water clarity: 2.1 ft visibility. Phosphorus: 53.5 µg/L. Chlorophyll-a (algae): 30.5 µg/L. Surface area: 195 acres.
Is Lake Geode safe to swim in?
- The F is nutrients and algae, not a swimming clearance. Lake Geode is listed impaired under Clean Water Act §303(d) (IR 5) for mercury, pathogens (E. coli, fecal), pH / acidity. Check local advisories before you swim.
What is the water temperature of Lake Geode?
- Lake Geode typically sits around 73°F at the surface in September, from 23 EPA Water Quality Portal field readings (2010–2023). That is a typical value for the month, not a live reading.
Explore Lake Geode across LakeQuality
More Iowa Lake Rankings
Other Grade F Lakes in Iowa
Hypereutrophic Lakes in Iowa
Where this data comes from
52 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_WQX52 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)
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
Regulated discharger data from EPA ECHO (ICIS-NPDES)