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Iola Lake

Waupaca County, WisconsinMesotrophic

Iola Lake sits at the top of the Wisconsin DNR grading rubric with an A, a mark reached by the cleanest lakes in Wisconsin. The three sub-grades — clarity, phosphorus, and chlorophyll-a — track close together, so no single parameter is dragging the average.

A TSI near 44 places Iola Lake in the mesotrophic band — moderate productivity, with seasonal swings between clearer spring water and richer late-summer conditions. The lake's maximum depth is not yet documented in state morphometric records — context for its physical structure remains limited. At 220 acres, Iola Lake fits the Wisconsin median for monitored lakes, with partial shoreline records. Iola Lake sits at rank 13 of 25 in Waupaca County, in the lower half of the local distribution.

Iola Lake carries an invasive watermilfoil record — boat-launch decontamination and shoreline care matter more here than at uninfested lakes. The fishery is bass-led, with 3 documented species across the lake's records. Public access is available — the lake is on the Wisconsin DNR public-access list. Monitoring depth is thin here: the LakeGrade rubric is applied to a small number of sample years, and the grade will be revised as more data accumulates.

Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2023-08-22. Grade methodology: LakeGrade methodology.

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Swimming Safety

Excellent for swimming, crystal clear water with minimal algae

Water Quality Grade: A, Excellent

Good clarity, visible to about 10 ft. Phosphorus level: 16.4 µg/L. Trophic State Index: 44.

MetricValueGrade
Water Clarity (Secchi Depth)10 ftB
Phosphorus16.4 µg/LA
Chlorophyll-a (Algae)No data
Trophic State Index (TSI)44Mesotrophic

Moderate nutrients, good water quality

Lake Details

CharacteristicValue
Surface Area220 acres
Public AccessYes

Fish Species

Click a species to see every graded lake where it is documented.

→ Best fishing times for Iola Lake (14-day solunar calendar)

→ Is it safe to eat fish from Iola Lake? (mercury & PFAS guide)

Iola Lake fishing regulations (limits, seasons, special rules)

Invasive & Introduced Species

Red chips are ecologically harmful invasive species. Gray chips are stocked or introduced fish that aren't a current ecological concern.

Banded Mystery SnailCurly-Leaf PondweedEurasian Water-MilfoilHybrid Eurasian / Northern Water-MilfoilPurple Loosestrife

Water Quality Trend: Declining

Based on 7 years of monitoring data (2020-2025).

MetricTrendChange/YearYears
Water Clarity Declining-0.357 m/yr6
Phosphorus Stable-0.25 µg/L/yr7
See year-by-year chart →

Recreation & Access

1
Boat Landings
Yes
Public Access

Location

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County Ranking

Ranked #13 of 25 lakes in Waupaca County

Nearby Lakes in Waupaca County

WI DNR Lake Profile

Authoritative data from the Wisconsin DNR LakePages. 4 stations on file (most recent sample 2023).

DNR Assessment
Excellent · Reservoir lake
Trophic State Index 41 (mesotrophic) · 5-year average

Fish Species (DNR-rated)

Panfish(Abundant)Largemouth Bass(Common)Northern Pike(Common)

Reservoir Info (USACE NID)

Iola Lake is a man-made reservoir impounded by the Iola (completed 1865), built primarily for recreation on the SOUTH BRANCH LITTLE WOLF; gravity-type dam, 12 ft tall and 694 ft long.

Surface area
206 ac
Normal storage
638 ac-ft
Max storage
1,000 ac-ft
Drainage area
100 sq mi
Hazard class
Significant
Owner
Village Of Iola

Source: USACE National Inventory of Dams, NID ID WI00337 · Operator website

Data Sources

Water quality data from the EPA Water Quality Portal

Grading methodology based on Metropolitan Council standards

Fish and recreation data from Wisconsin DNR Lakes

Public boat-access points from the USGS National Boat Ramps inventory

Most recent sample: 2023-08-22

Monitoring stations: 1

Where to stay near Iola Lake

Compare lakeside cabins, hotels, and vacation rentals near Iola Lake in Waupaca County, Wisconsin — live availability and prices for your trip.

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