Whitehorse Lake
Coconino County, ArizonaView mapDirections
Not enough samples to grade — no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years). No letter yet. Here is what we do have.
- Public access
- Limited data
Whitehorse Lake in Coconino County, Arizona is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 1.6 ft visibility. Phosphorus: 190 µg/L.
- Clarity
- 1.6 ft
- Phosphorus
- 190 µg/L
- Trend
- ↓ Declining
- Public access
- Yes
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Stays near Whitehorse Lake
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Watch Whitehorse Lake’s letter
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Why Whitehorse Lake has no grade
We grade a lake only when the monitoring record supports a letter: at least three phosphorus or chlorophyll-a samples in the last ten years, scored against EPA National Lakes Assessment thresholds for this lake’s ecoregion. For Whitehorse Lake, no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years). Sampling here has recorded water clarity and phosphorus, but not algae (chlorophyll-a).
Not Rated is not an F. It is EPA Integrated Reporting Category 3 — insufficient information. The water here may be excellent or poor; nobody has measured enough of it to say. Everything below that has been measured is still reported on this page.
Sampling is run by ADEQ and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
Whitehorse Lake is a lake in Coconino County, Arizona. Overall water quality is declining over recent sampling years. Limited fish-species data available. Public access is available with 1 public boat landing.
Source: EPA Water Quality Portal sampling records, ADEQ, last sampled 2025-10-30. Grade methodology: LakeQuality methodology.
What Whitehorse Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
Swimming Safety
Not ratedLimited data
The letter is not a swimming clearance. Check local advisories before you swim.
Water quality measurements for Whitehorse Lake
These readings exist but are not enough for an A–F grade — see why.
Very murky, less than 1.6 ft of visibility. Phosphorus 190 µg/L. TSI 75.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1.6 ft | Not graded |
| Phosphorus | 190 µg/L | Not graded |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 75 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Recreation & Access
- Whitehorse LakePublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fishing Whitehorse Lake
Water Quality Trend: ↓ Declining
Based on 4 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.048 m/yr | 4 |
| Phosphorus | ↓ Declining | +10.84 µg/L/yr | 4 |
Reservoir Info (USACE NID)
Whitehorse Lake is a man-made reservoir impounded by the Whitehorse Dam (completed 1938), built primarily for fish and wildlife pond on the Trib.Of Sycamore Creek; earth-type dam, 31 ft tall and 400 ft long.
- Normal storage
- 260 ac-ft
- Max storage
- 260 ac-ft
- Drainage area
- 3 sq mi
- Hazard class
- Low
- Owner
- USDA FS
All listed purposes: Fish and Wildlife Pond;Recreation.
Source: USACE National Inventory of Dams, NID ID AZ82403 · Operator website
Nearby Lakes in Coconino County
Frequently asked questions about Whitehorse Lake
Where is Whitehorse Lake?
- Whitehorse Lake is a lake in Coconino County, Arizona. LakeQuality has not rated this lake (UNRATED) — no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years).
What is the water quality grade for Whitehorse Lake?
- Whitehorse Lake in Coconino County, Arizona is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 1.6 ft visibility. Phosphorus: 190 µg/L.
Is Whitehorse Lake safe to swim in?
- The letter is not a swimming clearance. Check local advisories before you swim.
Are there boat ramps on Whitehorse Lake?
- Whitehorse Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Whitehorse Lake. Public access is listed as yes.
Explore Whitehorse Lake across LakeQuality
Planning a trip around Montezuma Castle?
Whitehorse Lake is about 36 miles from Montezuma Castle National Monument. Crowds there swing hard by season, so the month you pick changes both how busy the park is and what lodging costs.
Best time to visit Montezuma Castle →More Arizona Lake Rankings
Other Lakes in Arizona
Hypereutrophic Lakes in Arizona
Where this data comes from
11 measurements from 1 monitoring station, 2022–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Great Lakes Environmental Center
GLEC11 samples · 2022–2025
Analytical methods
- 4500 P E ~ Phosphorus in Water by Colorimetry- Ascorbic Acid Method
- 300.0 ~ EPA; Determination of Inorganic Anions by Ion Chromatography
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
Named boat-access points from the USGS National Boat Ramps inventory