Sand Lake
Marshall County, IowaView mapDirections
Clarity, phosphorus, and algae all sit in the cleanest band for this region.
↑ up from B at the last regrade
- Mesotrophic
- #1 of 2 in the county
- 36 ft max depth
Sand Lake in Marshall County, Iowa has a water quality grade of A (Excellent). Water clarity: 6.4 ft visibility. Phosphorus: 25 µg/L. Chlorophyll-a (algae): 3.6 µg/L.
- Clarity
- 6.4 ft
- Max depth
- ~36 ft est.
- Type
- Mesotrophic
- Phosphorus
- 25 µg/L
- Chlorophyll-a
- 3.6 µg/L
- Trend
- ↓ Declining
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Watch Sand Lake’s letter
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Sand Lake is a mesotrophic lake in Marshall County, Iowa with an estimated average depth of about 36 feet. Water quality is graded A based on 2 sampling years through 2024. Overall water quality is declining over recent sampling years. Compared to the 1 other monitored lakes in Marshall County, Sand Lake ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, Iowa DNR, last sampled 2024-09-11. Grade methodology: LakeQuality methodology.
Swimming Safety
Grade onlyLow algae
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 A is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
Water Quality Grade: A (Excellent)
Murky, only visible to about 6.4 ft. Phosphorus 25 µg/L. Chlorophyll-a 3.6 µg/L. TSI 48. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 6.4 ft | Not graded |
| Phosphorus | 25 µg/L | Good |
| Chlorophyll-a (Algae) | 3.6 µg/L | Good |
| Trophic State Index (TSI) | 48 | Mesotrophic |
Moderate nutrients, good water quality
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~36 ft est. |
| Average Depth | ~9 ft est. |
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Iowa has not published bathymetry for Sand Lake.
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth here is modelled, not surveyed — HydroLAKES v1.0 estimates lake depth from surrounding terrain rather than from soundings. Treat it as an approximation, and prefer a state bathymetric survey where one exists.
Fishing Sand Lake
Water Quality Trend: ↓ Declining
Based on 2 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -1.35 m/yr | 2 |
| Phosphorus | ↓ Declining | +20.5 µg/L/yr | 2 |
| Chlorophyll-a | ↓ Declining | +6.8 µg/L/yr | 2 |
Regulated Pollution Sources Nearby
10 EPA-permitted facilities operate within about 5 miles of Sand Lake under Clean Water Act (NPDES) discharge permits, including 1 classified by the EPA as major discharger. 2 facilities have a reported Clean Water Act violation in the past three years.
- Marshalltown City Of Water Pollution ControlMarshalltown · 2 mi away · NPDES IA0038610MajorRecent violation
- Bruin Manufacturing Co., Inc.Marshalltown · 2.1 mi away · NPDES IA0081434Recent violation
- Ipl - Sutherland StationMarshalltown · 0.8 mi away · NPDES IA0000108
- Ipl - Precision Pipeline, LlcCedar Rapids · 1.5 mi away · NPDES IA0052365
- Marshalltown, City Of MS4Marshalltown · 2 mi away · NPDES IA0080039
- Fisher Controls International Llc (Main Office)Marshalltown · 2.1 mi away · NPDES IA0000230
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 #1 of 2 lakes in Marshall County
Nearby Lakes in Marshall County
Frequently asked questions about Sand Lake
Where is Sand Lake?
- Sand Lake is a lake in Marshall County, Iowa. LakeQuality grades it A for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Sand Lake?
- Sand Lake in Marshall County, Iowa has a water quality grade of A (Excellent). Water clarity: 6.4 ft visibility. Phosphorus: 25 µg/L. Chlorophyll-a (algae): 3.6 µg/L.
Is Sand Lake safe to swim in?
- The A is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
How deep is Sand Lake?
- No published bathymetric survey covers Sand Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 36 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate.
Explore Sand Lake across LakeQuality
More Iowa Lake Rankings
Other Grade A Lakes in Iowa
Mesotrophic Lakes in Iowa
Where this data comes from
36 measurements from 1 monitoring station, 2023–2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Iowa DNR Surface Water Monitoring Data
21IOWA_WQX36 samples · 2023–2024
Analytical methods
- Unknown
- Phosphorus by Colorimetry
- 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
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Lake size & watershed from HydroLAKES (HydroSHEDS)