Union Lake
Branch County, Michigan544 acresView mapDirections
EGLE publishes the water-quality measurements for Union Lake. Here is what has been measured.
- Impaired · Nutrients (phosphorus, nitrogen)
- Public access
- Limited data
Union Lake in Branch County, Michigan has water-quality measurements published by EGLE, shown here as reported. Water clarity: 3.5 ft visibility. Surface area: 543.6 acres.
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.
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. Methodology: how these readings are compared.
What Union Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
- Fishing22 species recorded
Swimming conditions
No readingLimited data
Nutrient and algae readings are not a swimming clearance. Union Lake is listed impaired under Clean Water Act §303(d) (IR 5) for nutrients (phosphorus, nitrogen), pCBs. Check local advisories before you swim.
Whether Union Lake is safe to swim in today is a call for the Michigan Department of Environment, Great Lakes, and Energy (EGLE) and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Union Lake
These are the measurements EGLE publishes for Union Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Murky, only visible to about 3.5 ft. TSI 59.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 3.5ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | No reading The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential. | |
| Chlorophyll-a (algae) | No reading The green pigment in algae — a direct measure of how much algae is in the water. | |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 59 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Union Lake
Answers come straight from the public measurements and survey records on this page.
Lake Details
Surface area
544 acres
Public access
Yes
Listed by EGLE
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
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Stays near Union Lake
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Follow Union Lake’s readings
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Fish Species
Click a species to see every lake where it is documented.
Fishing Union Lake
Water quality readings over time
3 seasons of samples on record (2021–2023). Calling a direction takes at least 4 years of the same measurement.
Water clarity
Improving3 years
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
Designated uses not supporting: Aquatic life, Fish consumption.
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.
Nearby Lakes in Branch County
Frequently asked questions about Union Lake
Where is Union Lake?
- Union Lake is a lake in Branch County, Michigan. Its water-quality measurements are published by EGLE and shown on this page as reported.
What is the water quality of Union Lake?
- Union Lake in Branch County, Michigan has water-quality measurements published by EGLE, shown here as reported. Water clarity: 3.5 ft visibility. Surface area: 543.6 acres.
Is Union Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Union Lake is listed impaired under Clean Water Act §303(d) (IR 5) for nutrients (phosphorus, nitrogen), pCBs. Check local advisories before you swim.
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.
Can I fish at Union Lake?
- Union Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Seasons, size and bag limits, and whether you need a license are set by Michigan's fish and wildlife agency, so check its current regulations before you go.
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)
EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from 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