Skip to main content
LakeQuality
A

Day Lake

Vilas County, WisconsinLimited DataOligotrophic

On the LakeGrade rubric, Day Lake pulls an A: clarity readings still being added and 10 µg/L of phosphorus put it in the top bracket for Wisconsin. Sub-grades cluster within a single letter of each other, which usually means the lake is in stable trophic balance rather than fighting one specific stressor.

A TSI value of 38 puts Day Lake in the oligotrophic range, where biological productivity stays low and the water column remains clear. The lake's 57 ft maximum depth is in the upper tier for Wisconsin — deep enough for cold-water fish to find refuge in summer. At 110 acres, Day Lake fits the Wisconsin median for monitored lakes, with partial shoreline records. Among the 191 graded lakes in Vilas County, Day Lake ranks 46 — in the top quartile locally.

Day Lake has no invasive species recorded in Wisconsin state databases as of 2022, though prevention practices still apply at all access points. Bass fishing is part of the appeal: the species list runs to 2, anchored by largemouth and/or smallmouth bass. Public access is available — the lake is on the Wisconsin DNR public-access list. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.

Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2022-09-07. Grade methodology: LakeGrade methodology.

Watch Day Lake water quality

Subscribe for LakeQuality updates by email. No spam, unsubscribe anytime.

Swimming Safety

Excellent for swimming, crystal clear water with minimal algae

Water Quality Grade: A, Excellent

No clarity data. Phosphorus level: 10.2 µg/L. Trophic State Index: 38.

MetricValueGrade
Water Clarity (Secchi Depth)No data
Phosphorus10.2 µg/LA
Chlorophyll-a (Algae)No data
Trophic State Index (TSI)38Oligotrophic

Low nutrients, clear water, excellent for swimming

Lake Details

CharacteristicValue
Maximum Depth57 ft
Surface Area110 acres
Public AccessYes

Fish Species

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

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

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

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

Water Quality Trend: Declining

Based on 2 years of monitoring data (2020-2025).

MetricTrendChange/YearYears
Phosphorus Declining+1.1 µg/L/yr2

Recreation & Access

2
Boat Landings
Yes
Public Access

Location

Loading map…

County Ranking

Ranked #46 of 191 lakes in Vilas County

Nearby Lakes in Vilas County

WI DNR Lake Profile

Authoritative data from the Wisconsin DNR LakePages. 1 station on file (most recent sample 2022).

Fish Species (DNR-rated)

Panfish(Common)Smallmouth Bass(Present)

EPA Impairment Status

Day Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).

Causes of impairment

Mercury

Source: EPA ATTAINS assessment unit WI10003879 · Official waterbody report · Matched by proximity (2.95 km)

Data Sources

Water quality data from the EPA Water Quality Portal

Impairment status from EPA ATTAINS 303(d) database

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: 2022-09-07

Monitoring stations: 1

Where to stay near Day Lake

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

Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.