Glen Lake
Lincoln County, Montana300 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.
- Public access
- Limited data
Glen Lake in Lincoln County, Montana is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 19.9 ft visibility. Surface area: 300 acres.
- Clarity
- 19.9 ft
- Area
- 300 acres
- Trend
- ↓ Declining
- Public access
- Yes
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Watch Glen Lake’s letter
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Why Glen Lake has no grade
Glen 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, Glen Lake is Not Rated — not an F. Its 19.9-foot median from 10 readings collected 2020–2023 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 Montana DEQ and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
Glen Lake is a 300-acre lake in Lincoln County, Montana. Overall water quality is declining over recent sampling years. Limited fish-species data available. Public access is available with 1 public boat landing.
Source: EPA Water Quality Portal sampling records, Montana DEQ, last sampled 2023-07-24. Grade methodology: LakeQuality methodology.
What Glen Lake is good for
From access and monitoring records, not editorial picks.
- Clear water19.9 ft of visibility
- Boat launch1 documented ramp
Swimming Safety
Not ratedLimited data
The letter is not a swimming clearance. Check local advisories before you swim.
Water quality measurements for Glen Lake
These readings exist but are not enough for an A–F grade — see why.
Crystal clear, you can see 19.9 ft down. TSI 34.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 19.9 ft | Not graded |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 34 | Oligotrophic |
Low nutrients, clear water. The letter is not a swimming clearance.
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 300 acres |
| Public Access | Yes |
No bathymetric survey has been published for Glen Lake, so its depth is not documented here.
Recreation & Access
- Glen LakePublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fishing Glen Lake
Water Quality Trend: ↓ Declining
Based on 12 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.255 m/yr | 3 |
| Phosphorus | ↓ Declining | +0.21 µg/L/yr | 11 |
| Chlorophyll-a | ↑ Improving | -0.05 µg/L/yr | 12 |
Reservoir Info (USACE NID)
Glen Lake is a man-made reservoir impounded by the Glen Lake (completed 1950), built primarily for irrigation on the Lick Creek; earth-type dam, 14 ft tall and 700 ft long.
- Surface area
- 300 ac
- Normal storage
- 2,660 ac-ft
- Max storage
- 3,580 ac-ft
- Hazard class
- High
- Owner
- GLEN LAKE IRRIGATION DISTRICT
Source: USACE National Inventory of Dams, NID ID MT03756 · Operator website
Graded lakes near Glen Lake
Glen Lake has no grade, but these lakes within a short drive do.
Nearby Lakes in Lincoln County
Frequently asked questions about Glen Lake
Where is Glen Lake?
- Glen Lake is a lake in Lincoln County, Montana. 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 Glen Lake?
- Glen Lake in Lincoln County, Montana is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 19.9 ft visibility. Surface area: 300 acres.
Is Glen Lake safe to swim in?
- The letter is not a swimming clearance. Check local advisories before you swim.
Are there boat ramps on Glen Lake?
- Glen Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Glen Lake. Public access is listed as yes.
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Where this data comes from
10 measurements from 1 monitoring station, 2020–2023. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- North American Lake Management Society
NALMS10 samples · 2020–2023
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
Named boat-access points from the USGS National Boat Ramps inventory