Brown County Basement Water Guide (2026)

Updated October 29, 2026. General information only, not legal, engineering or geological advice. Rules and programs change, so confirm with the agency named before work starts.

Quick reference

Topic	What to know	Source
Precipitation	31.61 inches a year; 55.6 inches of snow (1991 to 2020)	NOAA, via Wikipedia
Soils	Glacial deposits 15 to 30 m thick; clay-rich red till	Wisconsin Geological and Natural History Survey
Near the bay	Flat bench 1 to 5 ft above water on the west side; poorly drained flats	USDA soil survey (1929)
Contracts	ATCP 110 covers basement waterproofing; written contract if you prepay or were solicited	Wisconsin Administrative Code
Permits	Seller must disclose required permits before you sign; no work until issued	ATCP 110.03
Before digging	Notify Diggers Hotline (811) at least 3 working days ahead	Wis. Stat. 182.0175
Sump discharge	Sump connections to the sanitary sewer are prohibited	NEW Water

What is under Brown County basements?

Glacial clay, mostly. In Pleistocene Geology of Brown County, Wisconsin (1985), the Wisconsin Geological and Natural History Survey describes the county as covered by glacial deposits 15 to 30 meters thick, which hold much of the county's groundwater. Early geologists assumed the area's red clay was lake sediment, but the survey notes that W. C. Alden showed in 1918 that much of it is actually till laid down by glaciers. Several till units are clay-rich: the Glenmore Member is a reddish-brown silty clay loam till averaging about 38 percent clay, and the Kirby Lake till averages 16 percent sand, 46 percent silt and 38 percent clay. A proglacial lake, glacial Lake Oshkosh, filled the Fox River lowland whenever ice blocked drainage to Green Bay, leaving fine lake sediment as well.

The USDA's 1929 soil survey of the county describes what that meant at the surface: Superior clay, with a heavy clay or silty clay topsoil that "puddles easily," covering its largest areas on each side of the Fox River southwest of Green Bay; a flat bench about two miles wide along the west side of the bay, 1 to 5 feet above the water; and Granby fine sand in low, poorly drained flats bordering the bay. Elevations ran from about 581 feet at the bay's water level to 590 feet at De Pere.

Why that leads to wet basements and bowed walls

Clay drains slowly, so rain and snowmelt stay in the soil around a foundation and press against the walls and the underside of the floor. In low areas near the bay, groundwater can sit only a few feet below the surface. Wet clay is heavy and swells, and freezing near the surface adds pressure in winter, which is why horizontal cracks and inward bowing are common in block basements. Green Bay's 1991 to 2020 normals are 31.61 inches of precipitation and 55.6 inches of snow a year, and snowmelt reaches the ground all at once in spring thaws.

What does Wisconsin's home improvement rule require?

Wisconsin's Department of Agriculture, Trade and Consumer Protection enforces ATCP 110, the home improvement practices rule, and basement waterproofing is listed as a home improvement. Key points:

A written contract is required when you're asked to pay anything before the work is done, or when the seller solicited you in person, by phone or mail away from its place of business, or by leaving a handbill at your home.
The contract must include the seller's name and address, a description of the work and principal materials, the total price including finance charges, start and completion dates, and any warranty, and you must get a copy before work starts or any payment is taken.
Before you sign, the seller must tell you about required building permits, and it can't start work until all required state and local permits are issued.
Sellers can't misrepresent licensing, bonding or insurance, and can't ask you to sign a completion slip or make final payment before the work is finished.
A buyer who suffers a monetary loss from a violation may sue and recover twice the loss, plus costs and reasonable attorney fees.

Who can pull a permit?

Wisconsin's Department of Safety and Professional Services issues the Dwelling Contractor credential to the owner, partner or chief executive of a contracting business that obtains building permits for one- and two-family homes. A dwelling contractor must carry a bond of at least $25,000 or general liability insurance of at least $250,000 per occurrence. Whether your particular waterproofing job needs a permit depends on your municipality and the scope, so ask the company and your local building inspection office.

What about digging?

Exterior drain tile, wall anchors, window well replacements and buried discharge lines all involve digging. Wisconsin law requires excavators to notify the one-call system, Diggers Hotline, at least three working days before nonemergency digging. Diggers Hotline says the call is free and applies to homeowners too; dial 811.

Where should sump pump water go?

Outside, not into the sanitary sewer. NEW Water, the Green Bay Metropolitan Sewerage District, was established in 1931, cleans an average of 41 million gallons of water a day, and serves 15 municipal customers in Northeast Wisconsin. It says that during wet weather it can receive three to five times its normal flow, and lists prohibited sump pump connections to the sanitary sewer among the sources of that clear water, along with leaky pipes and improper storm connections. If your sump is tied into a floor drain or laundry tub, ask about rerouting it outdoors.

How dry should the basement be?

The U.S. EPA recommends indoor humidity below 60 percent, ideally 30 to 50 percent, and drying water-damaged materials within one to two days to prevent mold. A dehumidifier helps in summer, but it can't keep up with liquid water coming through walls or floors.

What does waterproofing usually cost here?

We don't list price ranges because we couldn't verify a reliable local source, and costs vary widely between a single crack and drain tile plus wall stabilization. Ask for an itemized written proposal, which ATCP 110 effectively requires anyway when you pay up front.

Questions to ask a waterproofing company

Where is the water getting in, and how does your plan fix that spot?
Is my wall moving? Should an engineer look at it?
Does this job need a permit, and who holds the Dwelling Contractor credential that will pull it?
Where will the sump discharge, and how will you keep the line from freezing?
Can I see your written warranty, and does it transfer if I sell?
What payment is due before the work is finished?

Common questions

Why is Green Bay's soil so hard on basements?

Much of Brown County is covered by clay-rich glacial till and lake sediment that drains slowly and swells when wet, and low ground near the bay has a high water table. Both keep water pressing against foundation walls.

Can I connect my sump pump to the sanitary sewer in Brown County?

No. NEW Water lists sump pump connections to the sanitary sewer as prohibited because the clear water overloads the system during wet weather.

How much notice do I need before digging in Wisconsin?

At least three working days. Wisconsin law requires excavators to notify Diggers Hotline before nonemergency digging, and Diggers Hotline says homeowners should call 811 too.

Brown County, WI basement water guide (2026)