Ak-Chin Reservoir
Pinal County, ArizonaView mapDirections
Clarity, phosphorus, and algae sit in the clean band for this region.
- Mesotrophic
- #1 of 1 in the county
Ak-Chin Reservoir in Pinal County, Arizona has a water quality grade of B (Good). Phosphorus: 27.5 µg/L. Chlorophyll-a (algae): 4.2 µg/L.
- Type
- Mesotrophic
- Phosphorus
- 27.5 µg/L
- Chlorophyll-a
- 4.2 µg/L
- Trend
- ↑ Improving
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Watch Ak-Chin Reservoir’s letter
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Ak-Chin Reservoir is a mesotrophic lake in Pinal County, Arizona. Water quality is graded B based on 1 sampling years through 2026. Overall water quality is improving over recent sampling years.
Source: EPA Water Quality Portal sampling records, ADEQ, last sampled 2026-04-28. Grade methodology: LakeQuality methodology.
Swimming Safety
Grade onlyLow algae
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 B is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
Water Quality Grade: B (Good)
No clarity data. Phosphorus 27.5 µg/L. Chlorophyll-a 4.2 µg/L. TSI 48. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | 27.5 µg/L | Good |
| Chlorophyll-a (Algae) | 4.2 µg/L | Not graded |
| Trophic State Index (TSI) | 48 | Mesotrophic |
Moderate nutrients, good water quality
Fishing Ak-Chin Reservoir
Water Quality Trend: ↑ Improving
Based on 10 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Phosphorus | ↑ Improving | -0.8 µg/L/yr | 10 |
| Chlorophyll-a | ↑ Improving | -0.3 µg/L/yr | 2 |
County Ranking
Ranked #1 of 1 lakes in Pinal County
Nearby Lakes in Pinal County
Frequently asked questions about Ak-Chin Reservoir
Where is Ak-Chin Reservoir?
- Ak-Chin Reservoir is a lake in Pinal County, Arizona. LakeQuality grades it B for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Ak-Chin Reservoir?
- Ak-Chin Reservoir in Pinal County, Arizona has a water quality grade of B (Good). Phosphorus: 27.5 µg/L. Chlorophyll-a (algae): 4.2 µg/L.
Is Ak-Chin Reservoir safe to swim in?
- The B is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
Explore Ak-Chin Reservoir across LakeQuality
More Arizona Lake Rankings
Other Grade B Lakes in Arizona
Mesotrophic Lakes in Arizona
Where this data comes from
63 measurements from 1 monitoring station, 2012–2026. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Ak-Chin Indian Community (Tribal)
AK-CHIN_WQX63 samples · 2012–2026
Analytical methods
- DO NOT USE***4500 NH3 C ~ Ammonia in Water by Titrimetric Method
- 4500 SO4 D ~ Sulfate in Water by Gravimetric Analysis
- Phosphorus by Two Reagent Colorimetry
- 4500 P E ~ Phosphorus in Water by Colorimetry- Ascorbic Acid Method
- 4500 P F ~ Phosphorus in Water by Colorimetry Automated Ascorbic Acid Method
- 10200 H ~ Chlorophyll a-b-c Determination
- 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.