Lake Lillinonah
Lake Lillinonah in Litchfield County, Connecticut is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 8.3 ft visibility.
- Clarity
- 8.3 ft
- Public access
- Yes
Why Lake Lillinonah has no grade
We grade a lake only when its monitoring record clears the evidence bar: 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 Lake Lillinonah, 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. Sampling here has recorded water clarity, but not phosphorus and 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 your state environmental agency and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
Lake Lillinonah is a lake in Litchfield County, Connecticut. Limited fish-species data available. Public access is available with 2 public boat landings.
Source: EPA Water Quality Portal sampling records, your state environmental agency, last sampled 2024-08-27. Grade methodology: LakeGrade methodology.
Watch Lake Lillinonah water quality
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Swimming Safety
Not ratedLimited data
Not rated for swimming — there is not enough monitoring data to judge this lake
Water quality measurements for Lake Lillinonah
These readings exist but do not meet the evidence bar for an A–F grade — see why.
Moderate clarity, visible to about 8.3 ft. Trophic State Index: 47.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 8.3 ft | Not graded |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 47 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Lake Lillinonah
Compare lakeside cabins, hotels, and vacation rentals near Lake Lillinonah in Litchfield County, Connecticut — 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.
Top-rated places to stay near Lake Lillinonah
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Recreation & Access
- Lake LillinonahPublic
- Lake Lillinonah (Pond Brook)Public
Named access points from the USGS National Boat Ramps inventory, snapped within 5 km. More lakes with boat ramps
Fishing Lake Lillinonah
EPA Impairment Status
Lake Lillinonah is officially listed as impaired under Clean Water Act §303(d) in the 2022 EPA reporting cycle (IR category 5).
Causes of impairment
Source: EPA ATTAINS assessment unit CT6000-00-5+L1_01 · Official waterbody report · Matched by proximity (1.4 km)
Graded lakes near Lake Lillinonah
Lake Lillinonah has no grade, but these lakes within a short drive do.
Nearby Lakes in Litchfield County
Frequently asked questions about Lake Lillinonah
Where is Lake Lillinonah?
- Lake Lillinonah is a lake in Litchfield County, Connecticut. LakeQuality has not rated this lake (UNRATED) — there is not enough recent sampling to assign a letter.
What is the water quality grade for Lake Lillinonah?
- Lake Lillinonah in Litchfield County, Connecticut is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 8.3 ft visibility.
Is Lake Lillinonah safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. Lake Lillinonah is not rated for water quality — its monitoring record does not meet the evidence bar. Always check local health department advisories before swimming.
Are there boat ramps on Lake Lillinonah?
- Lake Lillinonah has 2 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Lake Lillinonah, Lake Lillinonah (Pond Brook). Public access is listed as yes.
Explore Lake Lillinonah across LakeGrade
More Connecticut Lake Rankings
Other Lakes in Connecticut
Mesotrophic Lakes in Connecticut
Where this data comes from
45 measurements from 3 monitoring stations, 2024. Retrieved from the EPA Water Quality Portal on 2026-08-21.
Collected and reported by
- CT DEEP Volunteer Water Monitoring Program (Volunteer)
CTVOLMON44 samples · 2024 - North American Lake Management Society
NALMS1 sample · 2024
Monitoring station identifiers (3)
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
Named boat-access points from the USGS National Boat Ramps inventory