Siloam Springs Lake
Benton County, ArkansasView mapDirections
Nutrients and algae run well above the regional average.
↓ down from D at the last regrade
- Hypereutrophic
- #3 of 4 in the county
- 37 ft max depth
- Limited data
Siloam Springs Lake in Benton County, Arkansas has a water quality grade of F (Algae-prone). Phosphorus: 70 µg/L. Chlorophyll-a (algae): 34.4 µg/L.
- Max depth
- ~37 ft est.
- Type
- Hypereutrophic
- Phosphorus
- 70 µg/L
- Chlorophyll-a
- 34.4 µg/L
- Trend
- ↑ Improving
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Stays near Siloam Springs Lake
Compare lakeside cabins, hotels, and vacation rentals near Siloam Springs Lake in Benton County, Arkansas — 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 Siloam Springs Lake are listed below.
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Watch Siloam Springs Lake’s letter
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Siloam Springs Lake is a highly nutrient-loaded hypereutrophic lake in Benton County, Arkansas with an estimated average depth of about 37 feet. Water quality is graded F based on 2 sampling years through 2026. Overall water quality is improving over recent sampling years. Compared to the 3 other monitored lakes in Benton County, Siloam Springs Lake ranks #3 for water quality.
Source: EPA Water Quality Portal sampling records, ADEQ, last sampled 2026-02-23. 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 F is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
Water Quality Grade: F (Algae-prone)
No clarity data. Phosphorus 70 µg/L. Chlorophyll-a 34.4 µg/L. TSI 65. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | 70 µg/L | Poor |
| Chlorophyll-a (Algae) | 34.4 µg/L | Poor |
| Trophic State Index (TSI) | 65 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~37 ft est. |
| Average Depth | ~13 ft est. |
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Arkansas has not published bathymetry for Siloam Springs 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 Siloam Springs Lake
Water Quality Trend: ↑ Improving
Based on 4 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Phosphorus | ↑ Improving | -2.08 µg/L/yr | 3 |
| Chlorophyll-a | → Stable | +0.11 µg/L/yr | 4 |
Reservoir Info (USACE NID)
Siloam Springs Lake is a man-made reservoir impounded by the Siloam Springs Lake Dam (completed 1952), built primarily for recreation on the Flint Creek; earth-type dam, 20 ft tall and 900 ft long.
- Normal storage
- 132 ac-ft
- Max storage
- 381 ac-ft
- Hazard class
- Low
- Owner
- City of Siloam Springs
Source: USACE National Inventory of Dams, NID ID AR00259 · Operator website
County Ranking
Ranked #3 of 4 lakes in Benton County
Nearby Lakes With Higher Grades
Siloam Springs Lake holds Grade F. 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 Benton County
Frequently asked questions about Siloam Springs Lake
Where is Siloam Springs Lake?
- Siloam Springs Lake is a lake in Benton County, Arkansas. LakeQuality grades it F for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Siloam Springs Lake?
- Siloam Springs Lake in Benton County, Arkansas has a water quality grade of F (Algae-prone). Phosphorus: 70 µg/L. Chlorophyll-a (algae): 34.4 µg/L.
Is Siloam Springs Lake safe to swim in?
- The F is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
How deep is Siloam Springs Lake?
- No published bathymetric survey covers Siloam Springs Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 37 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate.
Explore Siloam Springs Lake across LakeQuality
2 documented falls within 8 mi, nearest Natural Falls
Species activity outlook by water temperature and season
Where to stay at Arkansas's top lakes, each with its grade
Very high nutrients, dense algae, poor clarity
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Where this data comes from
39 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_WQX39 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)