Pasisades Reservoir
Bonneville County, IdahoView mapDirections
Nutrients and algae sit mid-range for this region.
↓ down from A at the last regrade
- Mesotrophic
- #3 of 6 in the county
- Public access
- Limited data
Pasisades Reservoir in Bonneville County, Idaho has a water quality grade of C (Fair). Water clarity: 10.5 ft visibility. Phosphorus: 15 µg/L. Chlorophyll-a (algae): 2.9 µg/L.
- Clarity
- 10.5 ft
- Type
- Mesotrophic
- Phosphorus
- 15 µg/L
- Chlorophyll-a
- 2.9 µg/L
- Trend
- → Stable
- Public access
- Yes
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Pasisades Reservoir is a mesotrophic lake in Bonneville County, Idaho. Water quality is graded C based on 2 sampling years through 2023. Water clarity is declining over recent sampling years. Limited fish-species data available. Public access is available with 1 public boat landing. Compared to the 5 other monitored lakes in Bonneville County, Pasisades Reservoir ranks #3 for water quality.
Source: EPA Water Quality Portal sampling records, IDEQ, last sampled 2023-06-29. Grade methodology: LakeQuality methodology.
What Pasisades Reservoir is good for
From access and monitoring records, not editorial picks.
- Clear water10.5 ft of visibility
- Boat launch1 documented ramp
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 C is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
Water Quality Grade: C (Fair)
Good clarity, visible to about 10.5 ft. Phosphorus 15 µg/L. Chlorophyll-a 2.9 µg/L. TSI 42. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 10.5 ft | Not graded |
| Phosphorus | 15 µg/L | Good |
| Chlorophyll-a (Algae) | 2.9 µg/L | Fair |
| Trophic State Index (TSI) | 42 | Mesotrophic |
Moderate nutrients, good water quality
Recreation & Access
- Blowout CanyonPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fishing Pasisades Reservoir
Water Quality Trend: → Stable
Based on 13 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.172 m/yr | 13 |
| Phosphorus | ↑ Improving | -1.41 µg/L/yr | 13 |
| Chlorophyll-a | → Stable | +0.03 µg/L/yr | 12 |
County Ranking
Ranked #3 of 6 lakes in Bonneville County
Nearby Lakes in Bonneville County
Frequently asked questions about Pasisades Reservoir
Where is Pasisades Reservoir?
- Pasisades Reservoir is a lake in Bonneville County, Idaho. LakeQuality grades it C for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Pasisades Reservoir?
- Pasisades Reservoir in Bonneville County, Idaho has a water quality grade of C (Fair). Water clarity: 10.5 ft visibility. Phosphorus: 15 µg/L. Chlorophyll-a (algae): 2.9 µg/L.
Is Pasisades Reservoir safe to swim in?
- The C is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
Are there boat ramps on Pasisades Reservoir?
- Pasisades Reservoir has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Blowout Canyon. Public access is listed as yes.
Explore Pasisades Reservoir across LakeQuality
12.5 mi away · 60 ft
4 thermal springs within 20.3 mi, nearest Alpine Warm Spring
Species activity outlook by water temperature and season
Where to stay at Idaho's top lakes, each with its grade
Moderate nutrients, good water quality
Idaho's cleanest and most-polluted lakes, ranked
More Idaho Lake Rankings
Other Grade C Lakes in Idaho
Mesotrophic Lakes in Idaho
Where this data comes from
20 measurements from 1 monitoring station, 2013–2023. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Bureau of Reclamation
1119USBR_WQX20 samples · 2013–2023
Analytical methods
- Depth, Secchi disk depth
- Zebra/Quagga Mussel APHA 10200G Modified
- Phosphorus by Single Reagent Colorimetry
- 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.
Other records on this page
Named boat-access points from the USGS National Boat Ramps inventory