Dale Maffitt Reservoir
Dallas County, Iowa230 acresView mapDirections
Iowa DNR publishes the water-quality measurements for Dale Maffitt Reservoir. Here is what has been measured.
- Mesotrophic
Dale Maffitt Reservoir in Dallas County, Iowa has water-quality measurements published by Iowa DNR, shown here as reported. Water clarity: 9.8 ft visibility. Phosphorus: 20 µg/L. Chlorophyll-a (algae): 2.1 µg/L. Surface area: 230 acres.
Dale Maffitt Reservoir is a 230-acre mesotrophic lake in Dallas County, Iowa. Overall water quality is improving over recent sampling years. Compared to the 1 other monitored lakes in Dallas County, Dale Maffitt Reservoir ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, Iowa DNR, last sampled 2022-09-07. Methodology: how these readings are compared.
Dale Maffitt Reservoir covers about 230 acres in Dallas County. Vrbo is where to look for cabins and lake homes around Dale Maffitt Reservoir, and Booking.com and Expedia search hotels near the lake for your dates.
What Dale Maffitt Reservoir is good for
From access and monitoring records, not editorial picks.
- Clear water9.8 ft of visibility
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 Dale Maffitt Reservoir 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 Dale Maffitt Reservoir
These are the measurements Iowa DNR publishes for Dale Maffitt Reservoir, 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 9.8 ft. Phosphorus 20 µg/L. Chlorophyll-a 2.1 µg/L. TSI 43.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 9.8ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 20µg/L | Good GoodFairPoor |
| Chlorophyll-a (algae) | 2.1µg/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. | 43 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
Ask about Dale Maffitt Reservoir
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Dale Maffitt Reservoir typically sits around 76°F at the surface in September. Summer average is about 78°F. Usually warmest in Jul (about 83°F) and coldest in Jun (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 (83°F).
Typical surface water temperature by month, from 9 field readings (2018–2022) via the EPA Water Quality Portal. See the full Dale Maffitt Reservoir water temperature breakdown →
Lake Details
Surface area
230 acres
No bathymetric survey has been published for Dale Maffitt Reservoir, so its depth is not documented here.
Stays via Stay22
Stays near Dale Maffitt Reservoir
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Fishing Dale Maffitt Reservoir
Water quality readings over time
3 seasons of samples on record (2020–2022). Calling a direction takes at least 4 years of the same measurement.
Water clarity
Improving3 years
Phosphorus
Improving-0.9 µg/L/yr3 years
Chlorophyll-a
Improving-0.4 µg/L/yr3 years
Reservoir Info (USACE NID)
Dale Maffitt Reservoir is a man-made reservoir impounded by the Maffitt Reservoir Dam (completed 1944), built primarily for water supply on the TR-RACCOON RIVER; earth-type dam, 79 ft tall and 1,800 ft long.
- Surface area
- 230 ac
- Normal storage
- 5,200 ac-ft
- Max storage
- 6,700 ac-ft
- Drainage area
- 1.41 sq mi
- Hazard class
- High
- Owner
- Des Moines Water Works
Source: USACE National Inventory of Dams, NID ID IA01338 · Operator website
Regulated Pollution Sources Nearby
3 EPA-permitted facilities operate within about 5 miles of Dale Maffitt Reservoir under Clean Water Act (NPDES) discharge permits. 1 facility has a reported Clean Water Act violation in the past three years.
- West Des Moines Water Works 88TH Street AsrWest Des Moines · 4 mi away · NPDES IA0053682Recent violation
- Cumming City Of StpCumming · 3.1 mi away · NPDES IA0071935
- Iowa Dot Rest Area #21 & #22 I80 WaukeeWaukee · 4.8 mi away · NPDES IA0068888
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 Dallas County
Frequently asked questions about Dale Maffitt Reservoir
Where is Dale Maffitt Reservoir?
- Dale Maffitt Reservoir is a lake in Dallas County, Iowa. Its water-quality measurements are published by Iowa DNR and shown on this page as reported.
What is the water quality of Dale Maffitt Reservoir?
- Dale Maffitt Reservoir in Dallas County, Iowa has water-quality measurements published by Iowa DNR, shown here as reported. Water clarity: 9.8 ft visibility. Phosphorus: 20 µg/L. Chlorophyll-a (algae): 2.1 µg/L. Surface area: 230 acres.
Is Dale Maffitt Reservoir 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 Dale Maffitt Reservoir?
- Dale Maffitt Reservoir typically sits around 76°F at the surface in September, from 9 EPA Water Quality Portal field readings (2018–2022). That is a typical value for the month, not a live reading.
Explore Dale Maffitt Reservoir across LakeQuality
Depth, room, public access, and the state wake-sport rules
Species activity outlook by water temperature and season
Where to stay at Iowa's top lakes, each with its readings
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Where this data comes from
36 measurements from 1 monitoring station, 2020–2022. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Iowa DNR Surface Water Monitoring Data
21IOWA_WQX36 samples · 2020–2022
Analytical methods
- Unknown
- Phosphorus by Colorimetry
- 445.0 ~ EPA; Chlorophyll and Pheophytin in Algae by Fluorescence
- 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)