Diamond Lake
Izard County, Arkansas116 acresView mapDirections
Clarity, phosphorus, and algae all sit in the cleanest band for this region.
- Oligotrophic
- #1 of 2 in the county
- 33 ft max depth
- Limited data
Diamond Lake in Izard County, Arkansas has a water quality grade of A (Excellent). Phosphorus: 20 µg/L. Chlorophyll-a (algae): 1.9 µg/L. Surface area: 116 acres.
- Max depth
- ~33 ft est.
- Area
- 116 acres
- Type
- Oligotrophic
- Phosphorus
- 20 µg/L
- Chlorophyll-a
- 1.9 µg/L
- Trend
- → Stable
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Diamond Lake is a 116-acre cold, clear oligotrophic lake in Izard County, Arkansas with an estimated average depth of about 33 feet. Water quality is graded A based on 2 sampling years through 2026. Compared to the 1 other monitored lakes in Izard County, Diamond Lake ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, ADEQ, last sampled 2026-02-09. 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 A is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
Water Quality Grade: A (Excellent)
No clarity data. Phosphorus 20 µg/L. Chlorophyll-a 1.9 µg/L. TSI 42. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | 20 µg/L | Not graded |
| Chlorophyll-a (Algae) | 1.9 µg/L | Good |
| Trophic State Index (TSI) | 42 | Oligotrophic |
Low nutrients, clear water. The letter is not a swimming clearance.
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~33 ft est. |
| Average Depth | ~16 ft est. |
| Surface Area | 116 acres |
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Arkansas has not published bathymetry for Diamond 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 Diamond Lake
Water Quality Trend: → Stable
Based on 3 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Chlorophyll-a | → Stable | +0.03 µg/L/yr | 3 |
Reservoir Info (USACE NID)
Diamond Lake is a man-made reservoir impounded by the Diamond Lake Dam (completed 1974), built primarily for recreation on the Bens Creek; earth-type dam, 74 ft tall and 936 ft long.
- Surface area
- 116 ac
- Normal storage
- 2,360 ac-ft
- Max storage
- 3,000 ac-ft
- Drainage area
- 1.9 sq mi
- Hazard class
- Low
- Owner
- Horseshoe Bend MRID
Source: USACE National Inventory of Dams, NID ID AR00228 · Operator website
County Ranking
Ranked #1 of 2 lakes in Izard County
Nearby Lakes in Izard County
Frequently asked questions about Diamond Lake
Where is Diamond Lake?
- Diamond Lake is a lake in Izard County, Arkansas. LakeQuality grades it A for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Diamond Lake?
- Diamond Lake in Izard County, Arkansas has a water quality grade of A (Excellent). Phosphorus: 20 µg/L. Chlorophyll-a (algae): 1.9 µg/L. Surface area: 116 acres.
Is Diamond Lake safe to swim in?
- The A is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
How deep is Diamond Lake?
- No published bathymetric survey covers Diamond Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 33 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 116 acres.
Explore Diamond Lake across LakeQuality
Species activity outlook by water temperature and season
Where to stay at Arkansas's top lakes, each with its grade
Low nutrients, clear water. The letter is not a swimming clearance.
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Other Grade A Lakes in Arkansas
Oligotrophic Lakes in Arkansas
Where this data comes from
31 measurements from 1 monitoring station, 2012–2026. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Arkansas Department of Environmental Quality
ARDEQH2O_WQX31 samples · 2012–2026
Analytical methods
- 4500 P J ~ Persulfate Method for Simultaneous Determination of Total Nitrogen and Total Phosphorus
- 445.0 ~ EPA; Chlorophyll and Pheophytin in Algae by Fluorescence
- Turbidity by Nephelometry
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
Lake size & watershed from HydroLAKES (HydroSHEDS)