Loch Ayr Lake is a 78-acre productive, nutrient-rich eutrophic lake in Ringgold County, Iowa. 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: LakeGrade methodology.
Watch Loch Ayr Lake water quality
Subscribe for LakeQuality updates by email. No spam, unsubscribe anytime.
Swimming Safety
Swimming not recommended, poor water quality with high algae risk
Water Quality Grade: D, Poor
Very murky, less than 2 ft of visibility. Chlorophyll-a: 29.7 µg/L. Trophic State Index: 66.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 2 ft | F |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | 29.7 µg/L | D |
| Trophic State Index (TSI) | 66 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 78 acres |
Where to stay 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.
Top-rated places to stay near Loch Ayr Lake
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Planning a trip to Loch Ayr Lake?
Get lake water-quality report cards plus the best cabin & lodging deals near Loch Ayr Lake — straight to your inbox. No spam, unsubscribe anytime.
Planning a whole trip? See where to stay at Iowa’s top lakes →
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 |
| Chlorophyll-a | ↓ Declining | +6.5 µg/L/yr | 3 |
Water Temperature
Loch Ayr Lake averages about 82°F at the surface in summer, 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 →
Location & Depth Map
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.
County Ranking
Ranked #1 of 2 lakes in Ringgold County
Cleaner Lakes Within 30 Miles
Loch Ayr Lake holds Grade D. One nearby lake has a higher grade.
See full comparison →Nearby Lakes in Ringgold County
Explore Loch Ayr Lake across LakeGrade
More Iowa Lake Rankings
Other Grade D Lakes in Iowa
Eutrophic Lakes in Iowa
More records, surveys & data sources
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
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth is a modeled estimate.
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.
Data Sources
Water quality data from the EPA Water Quality Portal
Impairment status from EPA ATTAINS 303(d) database
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Lake size & watershed from HydroLAKES (HydroSHEDS)
Grading methodology based on Metropolitan Council standards
Most recent sample: 2022-09-06
Monitoring stations: 1