What is the water clarity of Marion Lake?

Secchi depth (water clarity) data is not available for Marion Lake.

Does Marion Lake have an algae problem?

Marion Lake has a chlorophyll-a (algae) level of 73 µg/L. That is high — the lake is at meaningful risk of harmful algal bloom advisories in summer.

How Clean Is Marion Lake?

Q: Is Marion Lake polluted?

Marion Lake shows pollution indicators consistent with nutrient over-enrichment (typically phosphorus from agricultural runoff, fertilizer, or failing septic systems). Its has a water quality grade of F (Algae-prone), reflecting elevated nutrient and algae levels.

Marion Lake is algae-prone, with a higher bloom risk in warm months. It received a water quality grade of F (Algae-prone) based on EPA monitoring data. Phosphorus: 71 µg/L. Chlorophyll-a (algae): 73 µg/L. Trophic State Index: 69.

Cleanliness Snapshot

Metric	Marion Lake	Minnesota avg
Overall Grade	F	C
Phosphorus	71 µg/L	<30 = clean
Chlorophyll-a (Algae)	73 µg/L	<10 = clean
Trophic State Index	69	<50 = clean

How does Marion Lake compare?

Marion Lake's grade of F falls below the Minnesota state average of C. It ranks #3 of 5 lakes in McLeod County by water quality score.

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More on Marion Lake

Is Marion Lake safe for swimming? →What fish are in Marion Lake? →Is Marion Lake polluted? →Full water quality report →McLeod County lakes →Cleanest lakes in McLeod County →Cleanest lakes in Minnesota →