Cast Gill

Grand Lake (Millpond)

Green Lake County, Wisconsin · WBIC 161100

Official regulationsDNR lake mapDepth map (PDF)

The DNR lists this lake's watershed (Lower Grand River) as suspect or infected with VHS, a fish virus. The listing covers the watershed, not a test of this lake. About VHS

Size

234 acres

Max depth

8 ft

DNR lake type

Simple, Riverine

Water clarity

5.5 ft

Moderate, measured May 2021

A river-like water type, with flow instead of a still basin. This describes the lake type in general, not this lake in particular.

Outline

Grand Lake Access1

Numbered dots are boat landings; tap one for directions. The list below has the same numbers. Drawn from the DNR's 24K hydrography (surveyed 1980), so the shape is approximate and a landing can sit a little off the shore. Open the DNR lake map.

Water clarity

5.5 ft Secchi depthModerateOlder reading

Last measured May 12, 2021. 15 readings on record, 2017 to 2021.

Typical summer clarity (June to September): 5 ft, moderate, from 11 readings (2018 to 2020).

Nothing has been measured in the last 5 years, so this may not match the lake today.

Measured at the monitoring station named “Grand Lake - CLMN Site (Deepest Spot)”.

Secchi depth is how far down a white disk stays visible. A bigger number means clearer water. Clear means a Secchi depth of 10 feet or more, moderate 5 to 10 feet, low under 5 feet.

Wisconsin DNR water monitoring (volunteer and staff), via the Water Quality Portal; station Grand Lake - CLMN Site (Deepest Spot). Checked Oct 23, 2026.

Water temperature

A typical year Modeled estimate

  • Ice goes outabout Apr 4 (Mar 30 to Apr 12)
  • Surface reaches 48°Fabout Apr 23 (Apr 11 to Apr 28)
  • Surface reaches 64°Fabout May 13 (May 8 to May 22)
  • June surface75°F, usually 74 to 77°F
  • July surface81°F, usually 79 to 82°F
  • August surface77°F, usually 74 to 79°F

Forms a warm top layer around May 17, lasting about 131 days.

A computer model of this lake's typical weather and water, built from 15 years, 2005 to 2019. Ranges show the middle half of years. The model was not calibrated against measured temperatures for this lake. It is an estimate, not a measurement.

Modeled: U.S. Geological Survey lake temperature data release (doi:10.5066/P9CA6XP8).

Today at the lake

Loading today's forecast…

Forecast: National Weather Service (no endorsement implied). Sunrise, sunset and moon phase are calculated. The moon phase can be a day off.

Fish recorded near this lake

Recorded in open fish survey and museum records (GBIF). A record shows a fish was found near this lake in that year, not that it is there now, and says nothing about how many. Most coordinates are rounded to about 1 km, so a record is attached only when one lake is the clear match.

Open fish survey and museum records from GBIF; datasets are listed on the sources page. Checked Oct 23, 2026.

Boat landings

Wisconsin DNR public boat access sites. Checked Oct 23, 2026.

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More lakes in Green Lake County

All Green Lake County lakes

Where this comes from

  • Size, depth and lake typeWisconsin DNR lake classifications, checked Oct 23, 2026
  • OutlineWisconsin DNR 24K hydrography, checked Oct 23, 2026
  • Regulations linkWisconsin DNR fishing regulations (linked, not restated), checked Oct 23, 2026
  • Boat landingsWisconsin DNR public boat access sites, checked Oct 23, 2026
  • Water clarityWisconsin DNR water monitoring, via the Water Quality Portal, checked Oct 23, 2026
  • Typical-year temperatureU.S. Geological Survey lake temperature model (modeled estimate), checked Oct 23, 2026
  • Fish recordedOpen fish survey and museum records, via GBIF, checked Oct 23, 2026
  • VHS statusWisconsin DNR VHS status by watershed, checked Oct 24, 2026
  • Depth map linkWisconsin DNR lake maps list, checked Oct 24, 2026

See data sources for what each source covers, and about for how the numbers are matched to lakes.

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