Lamb Lake
Johnson County, Indiana56 acresView 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.
- Limited data
Lamb Lake in Johnson County, Indiana is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 7.2 ft visibility. Surface area: 56.3 acres.
- Clarity
- 7.2 ft
- Area
- 56 acres
- Trend
- ↓ Declining
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Stays near Lamb Lake
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Watch Lamb Lake’s letter
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Why Lamb Lake has no grade
Lamb 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, Lamb Lake is Not Rated — not an F. Its 7.2-foot median from 3 readings collected 2021–2023 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 IDEM and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
Lamb Lake is a 56-acre lake in Johnson County, Indiana. Overall water quality is declining over recent sampling years.
Source: EPA Water Quality Portal sampling records, IDEM, last sampled 2023-07-11. Grade methodology: LakeQuality methodology.
Swimming Safety
Not ratedLimited data
The letter is not a swimming clearance. Check local advisories before you swim.
Water quality measurements for Lamb Lake
These readings exist but are not enough for an A–F grade — see why.
Moderate clarity, visible to about 7.2 ft. TSI 49.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 7.2 ft | Not graded |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 49 | Mesotrophic |
Moderate nutrients, good water quality
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 56 acres |
No bathymetric survey has been published for Lamb Lake, so its depth is not documented here.
Fishing Lamb Lake
Water Quality Trend: ↓ Declining
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | -0.023 m/yr | 5 |
| Phosphorus | ↓ Declining | +10.5 µg/L/yr | 5 |
| Chlorophyll-a | ↓ Declining | +1.1 µg/L/yr | 5 |
Reservoir Info (USACE NID)
Lamb Lake is a man-made reservoir impounded by the Lamb Lake Dam (completed 1937), built primarily for recreation on the UNNAMED TRIBUTARY BEAR CREEK; earth-type dam, 45 ft tall and 860 ft long.
- Surface area
- 56.3 ac
- Normal storage
- 1,600 ac-ft
- Max storage
- 1,600 ac-ft
- Drainage area
- 3.1 sq mi
- Hazard class
- High
- Owner
- THOMAS JOHNSON
Source: USACE National Inventory of Dams, NID ID IN00338 · Operator website
Regulated Pollution Sources Nearby
12 EPA-permitted facilities operate within about 5 miles of Lamb Lake under Clean Water Act (NPDES) discharge permits. 1 facility has a reported Clean Water Act violation in the past three years.
- Trafalgar WwtpTrafalgar · 4.7 mi away · NPDES IN0040681Recent violation
- Riviera Club RenovationsIndianapolis · 1.1 mi away · NPDES INR10N641
- Brown County Water Utility Inc Phase Ii Cr 400 W, 650 S & 450 W Water Main ExteTrafalgar · 1.2 mi away · NPDES INRA00857
- Transportation And Maintenance FacilityTrafalgar · 3.1 mi away · NPDES INRA04331
- Indian Creek Elementary SchoolTrafalgar · 3.3 mi away · NPDES INR10J806
- Nhj School Corporation New Facilities And RenovationsTrafalgar · 3.5 mi away · NPDES INRA08253
Facilities permitted to discharge under the Clean Water Act within ~5 miles; proximity does not by itself mean a facility affects this lake. Source: EPA ECHO (ICIS-NPDES), as of 2026-07.
Nearby Lakes in Johnson County
Frequently asked questions about Lamb Lake
Where is Lamb Lake?
- Lamb Lake is a lake in Johnson County, Indiana. 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 Lamb Lake?
- Lamb Lake in Johnson County, Indiana is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 7.2 ft visibility. Surface area: 56.3 acres.
Is Lamb Lake safe to swim in?
- The letter is not a swimming clearance. Check local advisories before you swim.
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Where this data comes from
3 measurements from 1 monitoring station, 2021–2023. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- North American Lake Management Society
NALMS3 samples · 2021–2023
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
Regulated discharger data from EPA ECHO (ICIS-NPDES)