Crystal Lake Max Depth
Hancock County, Iowa10 acresView mapDirections
Iowa DNR publishes the water-quality measurements for Crystal Lake Max Depth. Here is what has been measured.
- Hypereutrophic
- Impaired · Algal growth
- 58 ft max depth
- Public access
Crystal Lake Max Depth in Hancock County, Iowa has water-quality measurements published by Iowa DNR, shown here as reported. Water clarity: 1.6 ft visibility. Phosphorus: 99 µg/L. Chlorophyll-a (algae): 50.3 µg/L. Surface area: 9.7 acres.
Free interactive depth-contour map of Crystal Lake Max Depth, reaching a maximum surveyed depth of 18 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Iowa DNR.
Crystal Lake Max Depth is a 10-acre highly nutrient-loaded hypereutrophic lake in Hancock County, Iowa with an estimated average depth of about 58 feet. Overall water quality is improving over recent sampling years. Limited fish-species data available. Public access is available. Compared to the 1 other monitored lakes in Hancock County, Crystal Lake Max Depth ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, Iowa DNR, last sampled 2024-10-22. Methodology: how these readings are compared.
Swimming conditions
Readings onlyRecreation use not supported
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. Crystal Lake Max Depth is listed impaired under Clean Water Act §303(d) (IR 4A) for algal growth, turbidity. Check local advisories before you swim.
Whether Crystal Lake Max Depth 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 Crystal Lake Max Depth
These are the measurements Iowa DNR publishes for Crystal Lake Max Depth, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Very murky, less than 1.6 ft of visibility. Phosphorus 99 µg/L. Chlorophyll-a 50.3 µg/L. TSI 70.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 1.6ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 99µg/L | Poor GoodFairPoor |
| Chlorophyll-a (algae) | 50.3µg/L | Poor GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 70 | Hypereutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Very high nutrients, dense algae, poor clarity
Ask about Crystal Lake Max Depth
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Crystal Lake Max Depth typically sits around 70°F at the surface in September. Summer average is about 76°F. Usually warmest in Jul (about 80°F) and coldest in May (about 59°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (59°F) to its warmest (80°F).
Typical surface water temperature by month, from 29 field readings (2010–2023) via the EPA Water Quality Portal. See the full Crystal Lake Max Depth water temperature breakdown →
Lake Details
Max depth
~58 ft est.
Surface area
10 acres
Public access
Yes
Listed by Iowa DNR
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Iowa has not published bathymetry for Crystal Lake Max Depth.
Lake Size & Watershed
Watershed (drainage) area
5 sq mi
HydroLAKES / HydroSHEDS
Shoreline
2.8 mi
HydroLAKES / HydroSHEDS
Elevation
1,237 ft
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.
Stays via Stay22
Stays near Crystal Lake Max Depth
Compare lakeside cabins, hotels, and vacation rentals near Crystal Lake Max Depth in Hancock 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 readings cover nutrients and algae, not lodging. Cabins and rentals around Crystal Lake Max Depth are listed below.
Top-rated places to stay near Crystal Lake Max Depth
Prices for Oct 30–Nov 1, 4 adults. Change dates on the map below.
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Fishing Crystal Lake Max Depth
Water Quality Trend: Improving
Based on 5 years of monitoring (2020–2024).
Water clarity
Stable5 years
Phosphorus
Improving-4.45 µg/L/yr4 years
Chlorophyll-a
Improving-17.83 µg/L/yr5 years
Reservoir Info (USACE NID)
Crystal Lake Max Depth is a man-made reservoir impounded by the Crystal Lake Sediment Control Dam (completed 2003) on the Tr- West Fork Iowa River; earth-type dam, 27 ft tall and 625 ft long.
- Surface area
- 9.7 ac
- Normal storage
- 89 ac-ft
- Max storage
- 148 ac-ft
- Drainage area
- 0.36 sq mi
- Hazard class
- Low
- Owner
- Iowa Department of Natural Resources
Source: USACE National Inventory of Dams, NID ID IA03525 · Operator website · Matched by proximity (0.82 km)
EPA Impairment Status
Crystal Lake Max Depth is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).
Causes of impairment
Designated uses not supporting: Recreation.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit IA 02-IOW-781 · Official waterbody report
Nearby Lakes in Hancock County
Frequently asked questions about Crystal Lake Max Depth
Where is Crystal Lake Max Depth?
- Crystal Lake Max Depth is a lake in Hancock County, Iowa. Its water-quality measurements are published by Iowa DNR and shown on this page as reported.
What is the water quality of Crystal Lake Max Depth?
- Crystal Lake Max Depth in Hancock County, Iowa has water-quality measurements published by Iowa DNR, shown here as reported. Water clarity: 1.6 ft visibility. Phosphorus: 99 µg/L. Chlorophyll-a (algae): 50.3 µg/L. Surface area: 9.7 acres.
Is Crystal Lake Max Depth safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Crystal Lake Max Depth is listed impaired under Clean Water Act §303(d) (IR 4A) for algal growth, turbidity. Check local advisories before you swim.
What is the water temperature of Crystal Lake Max Depth?
- Crystal Lake Max Depth typically sits around 70°F at the surface in September, from 29 EPA Water Quality Portal field readings (2010–2023). That is a typical value for the month, not a live reading.
How deep is Crystal Lake Max Depth?
- No published bathymetric survey covers Crystal Lake Max Depth, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 58 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate. The lake covers 9.7 acres.
Can I fish at Crystal Lake Max Depth?
- Public access to Crystal Lake Max Depth is listed as yes on the lake record. Seasons, size and bag limits, and whether you need a license are set by Iowa's fish and wildlife agency, so check its current regulations before you go.
Explore Crystal Lake Max Depth across LakeQuality
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Where this data comes from
76 measurements from 1 monitoring station, 2020–2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Iowa DNR Surface Water Monitoring Data
21IOWA_WQX76 samples · 2020–2024
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
Impairment status from EPA ATTAINS 303(d) database
Lake size & watershed from HydroLAKES (HydroSHEDS)