What is the water quality grade for Marion Reservoir?

Marion Reservoir in Franklin County, Wisconsin received a water quality grade of B (Good). Water clarity: 5.9 ft visibility. Phosphorus: 16 µg/L. Chlorophyll-a (algae): 9.8 µg/L. Surface area: 7 acres.

Is Marion Reservoir safe to swim in?

Good for swimming, clear water with low algae levels. Marion Reservoir has an overall water quality grade of B. Algae concentration (chlorophyll-a) is 9.8 µg/L. Always check local health department advisories before swimming.

Marion Reservoir

Franklin County, WisconsinMesotrophic

Marion Reservoir is a 7-acre mesotrophic lake in Franklin County, MO. Water quality is graded B based on 3 sampling years through 2021. Compared to the 4 other monitored lakes in Franklin County, Marion Reservoir ranks #1 for water quality.

Source: EPA Water Quality Portal sampling records, local state DNR records, last sampled 2021-08-14. Grade methodology: LakeGrade methodology.

Swimming Safety

Good for swimming, clear water with low algae levels

Water Quality Grade: B, Good

Murky, only visible to about 5.9 ft. Phosphorus level: 16 µg/L. Chlorophyll-a: 9.8 µg/L. Trophic State Index: 50.

Metric	Value	Grade
Water Clarity (Secchi Depth)	5.9 ft	D
Phosphorus	16 µg/L	A
Chlorophyll-a (Algae)	9.8 µg/L	B
Trophic State Index (TSI)	50	Mesotrophic

Moderate nutrients, good water quality

Lake Details

Characteristic	Value
Surface Area	7 acres

Location

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County Ranking

Ranked #1 of 5 lakes in Franklin County

Cleaner Lakes Within 30 Miles

Marion Reservoir holds Grade B. 3 nearby lakes hold higher grades.

See full comparison →

Nearby Lakes in Franklin County

More Wisconsin Lake Rankings

Cleanest lakes in Wisconsin

Top 25 by overall water quality score

Best swimming lakes in Wisconsin

Grade A/B + low algae filter

Family fishing lakes in Wisconsin

Panfish-rich, public access

All Wisconsin lakes

Full state directory

Other Grade B Lakes in Wisconsin

Table Rock Lake

Taney County · Clarity: 10 ft

Whippoorwill Lake

Warren County · Clarity: 5 ft

Lake Taneycomo @ Rockaway Beach

Taney County · Clarity: 8.7 ft

Forest Lake

Adair County · Clarity: 4.1 ft

Fox Valley Lake

Clark County · Clarity: 8.5 ft

Sherwood Lake Nr. Dam

Warren County · Clarity: 5.9 ft

Mesotrophic Lakes in Wisconsin

Table Rock Lake Whippoorwill Lake Forest Lake Fox Valley Lake

Reservoir Info (USACE NID)

Marion Reservoir is a man-made reservoir impounded by the Lake Marion Dam (completed 1965), built primarily for recreation on the TR TO CLAVEY CREEK; earth-type dam, 30 ft tall.

Surface area: 7 ac
Normal storage: 70 ac-ft
Max storage: 112 ac-ft
Drainage area: 100 sq mi
Hazard class: Low
Owner: CALVEY LAKE SUBDV HMOWNS

Source: USACE National Inventory of Dams, NID ID MO30571 · Operator website

Data Sources

Water quality data from the EPA Water Quality Portal

Grading methodology based on Metropolitan Council standards

Most recent sample: 2021-08-14

Monitoring stations: 1