Carp Lake
Pierce County, WashingtonView mapDirections
Not Rated: one monitoring station are on record, but they measured water clarity only. LakeQuality’s A–F method grades total phosphorus, total nitrogen, chlorophyll-a, and turbidity; clarity is shown, not scored.
- Impaired · Nutrients (phosphorus, nitrogen)
- Public access
- Limited data
Carp Lake in Pierce County, Washington is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 6.6 ft visibility.
- Clarity
- 6.6 ft
- Trend
- ↑ Improving
- Public access
- Yes
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Stays near Carp Lake
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Watch Carp Lake’s letter
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Why Carp Lake has no grade
Carp Lake has monitoring on record from one station, but only water clarity was measured. LakeQuality’s A–F letter uses total phosphorus, total nitrogen, chlorophyll-a, and turbidity against EPA National Lakes Assessment condition classes. With none of those grading measurements on record, Carp Lake is Not Rated — not an F. Its 6.6-foot median from 3 readings collected 2012–2016 is still shown as clarity, but clarity alone cannot earn a letter.
Not Rated is EPA Integrated Reporting Category 3 — insufficient information. Everything below that has been measured is still reported on this page.
Sampling is run by WA Ecology and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
Carp Lake is a lake in Pierce County, Washington. Overall water quality is improving over recent sampling years. Limited fish-species data available. Public access is available.
Source: EPA Water Quality Portal sampling records, WA Ecology, last sampled 2016-07-10. Grade methodology: LakeQuality methodology.
Swimming Safety
Not ratedLimited data
The letter is not a swimming clearance. Carp Lake is listed impaired under Clean Water Act §303(d) (IR 5) for nutrients (phosphorus, nitrogen). Check local advisories before you swim.
Water quality measurements for Carp Lake
These readings exist but are not enough for an A–F grade — see why.
Murky, only visible to about 6.6 ft. TSI 50.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 6.6 ft | Not graded |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 50 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Fishing Carp Lake
Water Quality Trend: ↑ Improving
Based on 4 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.337 m/yr | 4 |
EPA Impairment Status
Carp Lake is officially listed as impaired under Clean Water Act §303(d) in the 2018 EPA reporting cycle (IR category 5).
Causes of impairment
Source: EPA ATTAINS assessment unit WA17110019001213_001_001 · Official waterbody report · Matched by proximity (2.17 km)
Graded lakes near Carp Lake
Carp Lake has no grade, but these lakes within a short drive do.
Nearby Lakes in Pierce County
Frequently asked questions about Carp Lake
Where is Carp Lake?
- Carp Lake is a lake in Pierce County, Washington. LakeQuality has not rated this lake (UNRATED) — the only measurement available is water clarity, which is not a water-quality indicator on its own — EPA's National Lakes Assessment does not grade clarity.
What is the water quality grade for Carp Lake?
- Carp Lake in Pierce County, Washington is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 6.6 ft visibility.
Is Carp Lake safe to swim in?
- The letter is not a swimming clearance. Carp Lake is listed impaired under Clean Water Act §303(d) (IR 5) for nutrients (phosphorus, nitrogen). Check local advisories before you swim.
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Where this data comes from
3 measurements from 1 monitoring station, 2012–2016. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- North American Lake Management Society
NALMS3 samples · 2012–2016
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
Impairment status from EPA ATTAINS 303(d) database