Base Line Lake
Washtenaw County, Michigan251 acresView mapDirections
EGLE publishes the water-quality measurements for Base Line Lake. Here is what has been measured.
- Impaired · Mercury
- Limited data
Base Line Lake in Washtenaw County, Michigan has water-quality measurements published by EGLE, shown here as reported. Water clarity: 11 ft visibility. Surface area: 251.4 acres.
Base Line Lake is a 251-acre lake in Washtenaw County, Michigan. Overall water quality is declining over recent sampling years. The lake supports 1 documented fish species including Brindled madtom.
Source: EPA Water Quality Portal sampling records, EGLE, last sampled 2024-07-11. Methodology: how these readings are compared.
What Base Line Lake is good for
From access and monitoring records, not editorial picks.
- Clear water11 ft of visibility
Swimming conditions
No readingLimited data
Nutrient and algae readings are not a swimming clearance. Base Line Lake is listed impaired under Clean Water Act §303(d) (IR 5) for mercury, pesticides, pFAS. Check local advisories before you swim.
Whether Base Line 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 Base Line Lake
These are the measurements EGLE publishes for Base Line Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Good clarity, visible to about 11 ft. TSI 43.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 11ft | 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. | 43 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
Ask about Base Line Lake
Answers come straight from the public measurements and survey records on this page.
Lake Details
Surface area
251 acres
No bathymetric survey has been published for Base Line Lake, so its depth is not documented here.
Stays via Stay22
Stays near Base Line Lake
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Fish Species
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Fishing Base Line Lake
Water Quality Trend: Worsening
Based on 9 years of monitoring (2016–2024).
Water clarity
Worsening9 years
Phosphorus
Worsening+1.24 µg/L/yr7 years
EPA Impairment Status
Base Line 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: Fish consumption.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MI040900050307-11 · Official waterbody report
Nearby Lakes in Washtenaw County
Frequently asked questions about Base Line Lake
Where is Base Line Lake?
- Base Line Lake is a lake in Washtenaw County, Michigan. Its water-quality measurements are published by EGLE and shown on this page as reported.
What is the water quality of Base Line Lake?
- Base Line Lake in Washtenaw County, Michigan has water-quality measurements published by EGLE, shown here as reported. Water clarity: 11 ft visibility. Surface area: 251.4 acres.
Is Base Line Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Base Line Lake is listed impaired under Clean Water Act §303(d) (IR 5) for mercury, pesticides, pFAS. Check local advisories before you swim.
What fish are in Base Line Lake?
- Fish species found in Base Line Lake include Brindled madtom. Base Line Lake is located in Washtenaw County, Michigan.
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Where this data comes from
108 measurements from 1 monitoring station, 2016–2024. Retrieved from the EPA Water Quality Portal on 2026-08-26.
Collected and reported by
- North American Lake Management Society
NALMS108 samples · 2016–2024
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