Rock Creek Max Depth Lake
Jasper County, Iowa640 acresView mapDirections
Iowa DNR publishes the water-quality measurements for Rock Creek Max Depth Lake. Here is what has been measured.
- Hypereutrophic
- Impaired · Algal growth
Rock Creek Max Depth Lake in Jasper County, Iowa has water-quality measurements published by Iowa DNR, shown here as reported. Water clarity: 1.1 ft visibility. Phosphorus: 167.5 µg/L. Chlorophyll-a (algae): 107.5 µg/L. Surface area: 640 acres.
Rock Creek Max Depth Lake is a 640-acre highly nutrient-loaded hypereutrophic lake in Jasper County, Iowa. Overall water quality is improving over recent sampling years. Compared to the 1 other monitored lakes in Jasper County, Rock Creek Max Depth Lake ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, Iowa DNR, last sampled 2024-09-05. Methodology: how these readings are compared.
Rock Creek Max Depth Lake covers about 640 acres in Jasper County. For a place on the water, look through cabin and lake-house rentals near Rock Creek Max Depth Lake on Vrbo. For a hotel or motel room, Booking.com and Expedia both search around the lake.
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.
Based on E. coli testing, Rock Creek Max Depth Lake never exceeded the EPA safe-swimming threshold (235 MPN/100mL) — on 0% of 25 samples across 7 seasons.
This is a historical summary of past testing, not a current condition — bacteria levels change quickly, especially after rain. Always check Iowa’s current beach and health-department advisories before swimming.
Whether Rock Creek Max Depth 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 Rock Creek Max Depth Lake
These are the measurements Iowa DNR publishes for Rock Creek Max Depth Lake, 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 1.1 ft of visibility. Phosphorus 167.5 µg/L. Chlorophyll-a 107.5 µg/L. TSI 77.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 1.1ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 168µg/L | Poor GoodFairPoor |
| Chlorophyll-a (algae) | 108µg/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. | 77 | Hypereutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Very high nutrients, dense algae, poor clarity
Ask about Rock Creek Max Depth Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Rock Creek Max Depth Lake typically sits around 67°F at the surface in September. Summer average is about 79°F. Usually warmest in Jul (about 81°F) and coldest in Sep (about 67°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (67°F) to its warmest (81°F).
Typical surface water temperature by month, from 33 field readings (2010–2023) via the EPA Water Quality Portal.
Lake Details
Surface area
640 acres
No bathymetric survey has been published for Rock Creek Max Depth Lake, so its depth is not documented here.
Stays via Stay22
Stays near Rock Creek Max Depth Lake
Compare lakeside cabins, hotels, and vacation rentals near Rock Creek Max Depth Lake in Jasper 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 Rock Creek Max Depth Lake are listed below.
Top-rated places to stay near Rock Creek Max Depth Lake
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Fishing Rock Creek Max Depth Lake
Water Quality Trend: Improving
Based on 5 years of monitoring (2020–2024).
Water clarity
Improving5 years
Phosphorus
Improving-12.2 µg/L/yr4 years
Chlorophyll-a
Improving-2.11 µg/L/yr5 years
Reservoir Info (USACE NID)
Rock Creek Max Depth Lake is a man-made reservoir impounded by the Rock Creek Dam, built primarily for recreation on the ROCK CREEK; earth-type dam, 33 ft tall and 1,500 ft long.
- Surface area
- 640 ac
- Normal storage
- 5,500 ac-ft
- Max storage
- 13,700 ac-ft
- Drainage area
- 41.4 sq mi
- Hazard class
- Significant
- Owner
- Iowa Department of Natural Resources
Source: USACE National Inventory of Dams, NID ID IA00537 · Operator website · Matched by proximity (0.19 km)
EPA Impairment Status
Rock Creek Max Depth Lake 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: Aquatic life, Recreation.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit IA 03-NSK-865 · Official waterbody report
Nearby Lakes in Jasper County
Frequently asked questions about Rock Creek Max Depth Lake
Where is Rock Creek Max Depth Lake?
- Rock Creek Max Depth Lake is a lake in Jasper County, Iowa. Its water-quality measurements are published by Iowa DNR and shown on this page as reported.
What is the water quality of Rock Creek Max Depth Lake?
- Rock Creek Max Depth Lake in Jasper County, Iowa has water-quality measurements published by Iowa DNR, shown here as reported. Water clarity: 1.1 ft visibility. Phosphorus: 167.5 µg/L. Chlorophyll-a (algae): 107.5 µg/L. Surface area: 640 acres.
Is Rock Creek Max Depth Lake safe to swim in?
- Based on E. coli testing, Rock Creek Max Depth Lake never exceeded the EPA safe-swimming threshold (235 MPN/100mL) — on 0% of 25 samples across 7 seasons. That is a historical summary of past bacteria testing, not a current reading and not a swimming clearance. Bacteria levels can spike quickly after heavy rain, so whether Rock Creek Max Depth Lake is safe to swim in today is a call for Iowa's water agency and the county health department; check their current beach advisories before you swim.
What is the water temperature of Rock Creek Max Depth Lake?
- Rock Creek Max Depth Lake typically sits around 67°F at the surface in September, from 33 EPA Water Quality Portal field readings (2010–2023). That is a typical value for the month, not a live reading.
Explore Rock Creek Max Depth Lake 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
- 2130 B ~ Nephelometric Method
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