Lake Orient is a 23-acre highly nutrient-loaded hypereutrophic lake in Adair County, Iowa. Water quality is graded F based on 2 sampling years through 2024. Overall water quality is declining over recent sampling years. Compared to the 4 other monitored lakes in Adair County, Lake Orient ranks #5 for water quality.
Source: EPA Water Quality Portal sampling records, Iowa DNR, last sampled 2024-09-29. Grade methodology: LakeGrade methodology.
Watch Lake Orient water quality
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Swimming Safety
Avoid swimming, very poor water quality, potential algae toxins
Water Quality Grade: F, Very Poor
Very murky, less than 1.3 ft of visibility. Chlorophyll-a: 110 µg/L. Trophic State Index: 75.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1.3 ft | F |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | 110 µg/L | F |
| Trophic State Index (TSI) | 75 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 23 acres |
Where to stay near Lake Orient
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Fishing Lake Orient
Water Quality Trend: ↓ Declining
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.02 m/yr | 5 |
| Chlorophyll-a | ↓ Declining | +19.48 µg/L/yr | 5 |
Water Temperature
Lake Orient averages about 78°F at the surface in summer, usually warmest in Jul (about 80°F) and coldest in Sep (about 70°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 29 field readings (2010–2023) via the EPA Water Quality Portal. See the full Lake Orient water temperature breakdown →
Location & Depth Map
Free interactive depth-contour map of Lake Orient, reaching a maximum surveyed depth of 10 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Iowa DNR.
County Ranking
Ranked #5 of 5 lakes in Adair County
Cleaner Lakes Within 30 Miles
Lake Orient holds Grade F. 2 nearby lakes hold higher grades.
- CMormon Trail LakeAdair County · 10.9 mi · Two grade letters higher (F → C)
- DNodaway LakeAdair County · 7.2 mi · Higher grade (F → D)
Nearby Lakes in Adair County
Explore Lake Orient across LakeGrade
More Iowa Lake Rankings
Other Grade F Lakes in Iowa
Hypereutrophic Lakes in Iowa
More records, surveys & data sources
Reservoir Info (USACE NID)
Lake Orient is a man-made reservoir impounded by the Orient Lake Dam (completed 1969), built primarily for water supply on the TR-EAST NODAWAY RIVER; earth-type dam, 23 ft tall and 867 ft long.
- Surface area
- 23.4 ac
- Normal storage
- 135 ac-ft
- Max storage
- 398 ac-ft
- Drainage area
- 0.94 sq mi
- Hazard class
- Significant
- Owner
- City of Orient
All listed purposes: Water Supply;Recreation.
Source: USACE National Inventory of Dams, NID ID IA00033 · Operator website
EPA Impairment Status
Lake Orient is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit IA 05-NOD-1396 · Official waterbody report
Regulated Pollution Sources Nearby
1 EPA-permitted facility operate within about 5 miles of Lake Orient under Clean Water Act (NPDES) discharge permits. 1 facility has a reported Clean Water Act violation in the past three years.
- Orient Stp (Sirwa)Orient · 1.5 mi away · NPDES IA0074535Recent 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)
Grading methodology based on Metropolitan Council standards
Most recent sample: 2024-09-29
Monitoring stations: 1