Portage Lake
St. Joseph County, MichiganView mapDirections
EGLE publishes the water-quality measurements for Portage Lake. Here is what has been measured.
- Oligotrophic
- Public access
- Limited data
Portage Lake in St. Joseph County, Michigan has water-quality measurements published by EGLE, shown here as reported. Water clarity: 5.5 ft visibility. Phosphorus: 31 µg/L. Chlorophyll-a (algae): 1.6 µg/L.
Portage Lake is a cold, clear oligotrophic lake in St. Joseph County, Michigan. Overall water quality is declining over recent sampling years. The lake supports 3 documented fish species including Chestnut lamprey, Common shiner, and Rainbow darter. Public access is available. Compared to the 7 other monitored lakes in St. Joseph County, Portage Lake ranks #7 for water quality.
Source: EPA Water Quality Portal sampling records, EGLE, last sampled 2023-09-23. Methodology: how these readings are compared.
What Portage Lake is good for
From access and monitoring records, not editorial picks.
- Fishing3 species recorded
Swimming conditions
Readings onlyLimited data
Based on clarity and algae readings from past sampling — there is no live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Whether Portage 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 Portage Lake
These are the measurements EGLE publishes for Portage 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 5.5 ft. Phosphorus 31 µg/L. Chlorophyll-a 1.6 µg/L. TSI 47.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 5.5ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 31µg/L | Fair GoodFairPoor |
| Chlorophyll-a (algae) | 1.6µg/L | Good GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 47 | Oligotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Low nutrients, clear water. No reading is a swimming clearance.
Ask about Portage Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Portage Lake typically sits around 64°F at the surface in September. Summer average is about 64°F. Usually warmest in Jul (about 65°F) and coldest in May (about 58°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (58°F) to its warmest (65°F).
Typical surface water temperature by month, from 277 field readings (2016–2019) via the EPA Water Quality Portal. See the full Portage Lake water temperature breakdown →
Stays via Stay22
Stays near Portage Lake
Compare lakeside cabins, hotels, and vacation rentals near Portage Lake in St. Joseph 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 Portage Lake
Prices for Oct 23–25, 4 adults. Change dates on the map below.
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Planning a whole trip? See where to stay at Michigan’s top lakes →
Follow Portage Lake’s readings
Email me when new measurements post for this lake. Updates stay free.
Or email
Fish Species
Click a species to see every lake where it is documented.
Fishing Portage Lake
Water Quality Trend: Worsening
Based on 7 years of monitoring (2016–2023).
Water clarity
Stable7 years
Phosphorus
Stable-0.01 µg/L/yr6 years
Chlorophyll-a
Worsening+0.21 µg/L/yr4 years
Regulated Pollution Sources Nearby
2 EPA-permitted facilities operate within about 5 miles of Portage Lake under Clean Water Act (NPDES) discharge permits. 1 facility has a reported Clean Water Act violation in the past three years.
- Th Plastics IncMendon · 4.4 mi away · NPDES MIG250278Recent violation
- Parkville Prairie FarmsThree Rivers · 1.6 mi away · NPDES MIG440036
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 St. Joseph County
Frequently asked questions about Portage Lake
Where is Portage Lake?
- Portage Lake is a lake in St. Joseph County, Michigan. Its water-quality measurements are published by EGLE and shown on this page as reported.
What is the water quality of Portage Lake?
- Portage Lake in St. Joseph County, Michigan has water-quality measurements published by EGLE, shown here as reported. Water clarity: 5.5 ft visibility. Phosphorus: 31 µg/L. Chlorophyll-a (algae): 1.6 µg/L.
Is Portage Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
What is the water temperature of Portage Lake?
- Portage Lake typically sits around 64°F at the surface in September, from 277 EPA Water Quality Portal field readings (2016–2019). That is a typical value for the month, not a live reading.
What fish are in Portage Lake?
- Fish species found in Portage Lake include Chestnut lamprey, Common shiner, Rainbow darter. Portage Lake is located in St. Joseph County, Michigan.
Can I fish at Portage Lake?
- Public access to Portage Lake is listed as yes on the lake record. 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 Portage Lake across LakeQuality
Fish species and the cleanest lakes across Michigan
Fish species and best lakes in St. Joseph County
Species activity outlook by water temperature and season
Where to stay at Michigan's top lakes, each with its readings
Michigan's cleanest lakes, ranked on agency measurements
More lakes in Michigan
Other Lakes in Michigan
Oligotrophic Lakes in Michigan
Where this data comes from
145 measurements from 1 monitoring station, 2016–2023. Retrieved from the EPA Water Quality Portal on 2026-08-26.
Collected and reported by
- Michigan EGLE - MiCorps
21MICH_MICORPS145 samples · 2016–2023
Analytical methods
- Phosphorus by Colorimetry
- 445.0 ~ EPA; Chlorophyll and Pheophytin in Algae by Fluorescence
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
Regulated discharger data from EPA ECHO (ICIS-NPDES)