Union Lake
Union Lake in Branch County, Michigan is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 3.5 ft visibility. Surface area: 543.6 acres.
- Clarity
- 3.5 ft
- Area
- 544 acres
- Trend
- ↑ Improving
- Public access
- Yes
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Free interactive depth-contour map of Union Lake, reaching a maximum surveyed depth of 16 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Michigan DNR.
Why Union Lake has no grade
We grade a lake only when the monitoring record supports a letter: 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 Union Lake, 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 EGLE and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
Union Lake is a 544-acre lake in Branch County, Michigan. Overall water quality is improving over recent sampling years. The lake supports 22 documented fish species including Barred fantail darter, Blackchin shiner, and Bluegill. Public access is available with 1 public boat landing.
Source: EPA Water Quality Portal sampling records, EGLE, last sampled 2022-09-20. Grade methodology: LakeQuality methodology.
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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 Union Lake
These readings exist but are not enough for an A–F grade — see why.
Murky, only visible to about 3.5 ft. Trophic State Index: 59.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 3.5 ft | Not graded |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 59 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Union Lake
Compare lakeside cabins, hotels, and vacation rentals near Union Lake in Branch County, Michigan — 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 Union Lake
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Planning a whole trip? See where to stay at Michigan’s top lakes →
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 544 acres |
| Public Access | Yes |
No bathymetric survey has been published for Union Lake, so its depth is not documented here.
Recreation & Access
- Union LakePublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Union Lake
Water Quality Trend: ↑ Improving
Based on 3 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.78 m/yr | 3 |
EPA Impairment Status
Union Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MI040500010403-03 · Official waterbody report
Regulated Pollution Sources Nearby
1 EPA-permitted facility operate within about 5 miles of Union Lake under Clean Water Act (NPDES) discharge permits. 1 facility has a reported Clean Water Act violation in the past three years.
- Union City WwtpUnion City · 3 mi away · NPDES MI0024244Recent violation
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.
Graded lakes near Union Lake
Union Lake has no grade, but these lakes within a short drive do.
Nearby Lakes in Branch County
Frequently asked questions about Union Lake
Where is Union Lake?
- Union Lake is a lake in Branch County, Michigan. LakeQuality has not rated this lake (UNRATED) — there is not enough recent sampling to assign a letter.
What is the water quality grade for Union Lake?
- Union Lake in Branch County, Michigan is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 3.5 ft visibility. Surface area: 543.6 acres.
Is Union Lake safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. Union Lake is not rated for water quality — its monitoring record does not meet the evidence bar. Always check local health department advisories before swimming.
What fish are in Union Lake?
- Fish species found in Union Lake include Barred fantail darter, Blackchin shiner, Bluegill, Bluntnose minnow, Brindled madtom, Brook silverside, Central mudminnow, Common shiner, Green sunfish, Iowa darter, Johnny darter, Lake herring, Longnose gar, Mimic shiner, Mottled sculpin, Rainbow darter, Rock bass, Sand shiner, Smallmouth bass, Spottail shiner, Western banded killifish, Yellow perch. Union Lake is located in Branch County, Michigan.
Are there boat ramps on Union Lake?
- Union Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Union Lake. Public access is listed as yes.
Explore Union Lake across LakeQuality
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Where this data comes from
18 measurements from 1 monitoring station, 2021–2022. Retrieved from the EPA Water Quality Portal on 2026-08-26.
Collected and reported by
- North American Lake Management Society
NALMS18 samples · 2021–2022
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
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Named boat-access points from the USGS National Boat Ramps inventory