Well Drilling in Door County, WI

Thin soil over cracked rock

Door County sits on dolomite, a limestone-like rock that holds most of the county's well water. Over much of the county, and especially north of Sturgeon Bay, the soil on top is thin or the rock is bare.

The rock near the surface is cracked. Once bacteria reach the water in those cracks, they can travel a long way in a short time. A USGS study of the county found the highest contamination in wells near septic systems and in areas of fractured rock near the surface, with the most bacteria showing up during and right after fast recharge, such as snowmelt or heavy rain.

Deeper casing

Because of that, the DNR requires extra well casing in Door County, so water comes from below the shallow zone that is more likely to be polluted. The casing is set and grouted into solid rock.

In the southwest part of the county, shale near the surface gives very little water. Going deeper there can bring water with more sulfate, hardness and iron, and deep wells may carry radium, a natural element. The driller weighs these for your lot.

Seasonal homes and cottages

A well that sits unused over winter still needs its yearly bacteria test. Test after the place opens in spring, once the snowmelt has soaked in, and any time the water changes.

If a cottage has an old well alongside a newer one, the old well must be filled and sealed by a licensed driller or pump installer.

Questions to ask

• How much casing does the DNR require on my lot, and how deep do you plan to set it?
• What did drillers find in nearby wells? Their Well Construction Reports are public.
• What water quality do deeper wells here tend to have?
• Where would the well sit relative to my septic system?