Loch Ayr Lake
Ringgold County, Iowa78 acresView mapDirections
Nutrients and algae run above the regional average.
- Eutrophic
- Impaired · Turbidity
- #1 of 2 in the county
- 30 ft max depth
- Limited data
Loch Ayr Lake in Ringgold County, Iowa has a water quality grade of D (Nutrient-rich). Water clarity: 2 ft visibility. Phosphorus: 69.5 µg/L. Chlorophyll-a (algae): 29.7 µg/L. Surface area: 78 acres.
- Clarity
- 2 ft
- Typical in September
- 70°F
- Max depth
- ~30 ft est.
- Area
- 78 acres
- Type
- Eutrophic
- Phosphorus
- 69.5 µg/L
- Chlorophyll-a
- 29.7 µg/L
- Trend
- ↓ Declining
Stays via Stay22
Stays near Loch Ayr Lake
Compare lakeside cabins, hotels, and vacation rentals near Loch Ayr Lake in Ringgold 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 Loch Ayr Lake are listed below.
Top-rated places to stay near Loch Ayr Lake
Prices for Sep 11–13, 4 adults. Change dates on the map below.
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Free interactive depth-contour map of Loch Ayr Lake, reaching a maximum surveyed depth of 17 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Iowa DNR.
Loch Ayr Lake is a 78-acre productive, nutrient-rich eutrophic lake in Ringgold County, Iowa with an estimated average depth of about 30 feet. Water quality is graded D based on 2 sampling years through 2022. Overall water quality is declining over recent sampling years. Compared to the 1 other monitored lakes in Ringgold County, Loch Ayr Lake ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, Iowa DNR, last sampled 2022-09-06. Grade methodology: LakeQuality methodology.
Swimming Safety
Grade onlyLimited data
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 D is nutrients and algae, not a swimming clearance. Loch Ayr Lake is listed impaired under Clean Water Act §303(d) (IR 5) for turbidity. Check local advisories before you swim.
Water Quality Grade: D (Nutrient-rich)
Very murky, less than 2 ft of visibility. Phosphorus 69.5 µg/L. Chlorophyll-a 29.7 µg/L. TSI 66. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 2 ft | Not graded |
| Phosphorus | 69.5 µg/L | Poor |
| Chlorophyll-a (Algae) | 29.7 µg/L | Poor |
| Trophic State Index (TSI) | 66 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Water Temperature
Loch Ayr Lake typically sits around 70°F at the surface in September. Summer average is about 82°F. Usually warmest in Jul (about 82°F) and coldest in May (about 68°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 9 field readings (2018–2022) via the EPA Water Quality Portal. See the full Loch Ayr Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~30 ft est. |
| Average Depth | ~12 ft est. |
| Surface Area | 78 acres |
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Iowa has not published bathymetry for Loch Ayr 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 Loch Ayr Lake
Water Quality Trend: ↓ Declining
Based on 3 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.275 m/yr | 3 |
| Phosphorus | ↓ Declining | +23.75 µg/L/yr | 3 |
| Chlorophyll-a | ↓ Declining | +6.5 µg/L/yr | 3 |
Reservoir Info (USACE NID)
Loch Ayr Lake is a man-made reservoir impounded by the Mount Ayr Reservoir Dam (completed 1930), built primarily for water supply on the TR-WALNUT CREEK; earth-type dam, 40 ft tall and 1,200 ft long.
- Surface area
- 78 ac
- Normal storage
- 780 ac-ft
- Max storage
- 1,410 ac-ft
- Drainage area
- 4.05 sq mi
- Hazard class
- Significant
- Owner
- City of Mounty Ayr
Source: USACE National Inventory of Dams, NID ID IA01370 · Operator website
EPA Impairment Status
Loch Ayr Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Source: EPA ATTAINS assessment unit IA 05-GRA-1381 · Official waterbody report
Regulated Pollution Sources Nearby
1 EPA-permitted facility operate within about 5 miles of Loch Ayr Lake under Clean Water Act (NPDES) discharge permits. 1 facility has a reported Clean Water Act violation in the past three years.
- Mount Ayr City Of StpMount Ayr · 2.5 mi away · NPDES IA0023574Recent violation
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 Ringgold County
Nearby Lakes With Higher Grades
Loch Ayr Lake holds Grade D. One nearby lake has a higher nutrient-and-algae grade — useful for a swim day, not a reason to skip lodging here.
Nearby Lakes in Ringgold County
Frequently asked questions about Loch Ayr Lake
Where is Loch Ayr Lake?
- Loch Ayr Lake is a lake in Ringgold County, Iowa. LakeQuality grades it D for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Loch Ayr Lake?
- Loch Ayr Lake in Ringgold County, Iowa has a water quality grade of D (Nutrient-rich). Water clarity: 2 ft visibility. Phosphorus: 69.5 µg/L. Chlorophyll-a (algae): 29.7 µg/L. Surface area: 78 acres.
Is Loch Ayr Lake safe to swim in?
- The D is nutrients and algae, not a swimming clearance. Loch Ayr Lake is listed impaired under Clean Water Act §303(d) (IR 5) for turbidity. Check local advisories before you swim.
What is the water temperature of Loch Ayr Lake?
- Loch Ayr Lake typically sits around 70°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.
How deep is Loch Ayr Lake?
- No published bathymetric survey covers Loch Ayr Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 30 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 78 acres.
Explore Loch Ayr Lake across LakeQuality
More Iowa Lake Rankings
Other Grade D Lakes in Iowa
Eutrophic Lakes in Iowa
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)
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)
Lake size & watershed from HydroLAKES (HydroSHEDS)