Well Depth, Local Geology and Missouri Well Records

"How deep will it be?" is the first question almost everyone asks about a new well. The honest answer around the Lake of the Ozarks is a range, not a number. This page explains why, and how to use the public records Missouri keeps to narrow that range.

Why depth and yield vary here

The Lake of the Ozarks region sits on thick layers of dolomite and limestone. In much of the area that rock is karst: groundwater moves through fractures and openings dissolved in the rock, not through a uniform layer like a sponge. ^[1]

That has two practical effects:

• Depth varies. A well reaches usable water where it crosses enough water-bearing openings. Those openings are unevenly spread, so neighboring wells can reach water at quite different depths.
• Yield varies. How much water a well produces depends on the openings it crosses. A deeper well is not automatically a better producer.

Soil cover is also thin and stony in many places, which is why casing and grout matter so much. In karst, contamination that reaches the aquifer can travel quickly to nearby wells. ^[1]

Missouri's drilling-area map (WISDIM)

The Missouri Department of Natural Resources publishes an interactive map, WISDIM, showing the state's thirteen drilling areas. ^[2] Each area has construction requirements based on its geology, hydrology and environmental factors, such as how much casing is required. Around the lake, land within a quarter mile of where the water reaches 20 feet deep is its own drilling area. ^[3] The map shows the rules for a location. It does not predict what a particular well will find.

Looking up well records (WIMS)

WIMS, the Missouri Well Information Management System, is the state's public database of well records and permitted contractors. ^[4] It is useful when you are:

• Buying land. Records for nearby wells show the depths and casing lengths other wells in the area needed.
• Buying a house with a well. If the well was drilled after July 1987, its record may show its depth, casing and construction date.
• Choosing a contractor. You can confirm that a well or pump installation contractor holds a current Missouri permit.

What WIMS cannot do:

• It has little or nothing for older wells. Wells drilled before July 1987 are generally not in it, and many long-established rural wells predate that.
• It describes the well as built. It says nothing about the pump, the pressure system, or the water quality today.
• Nearby records are evidence, not a forecast for your lot.

Why no one should promise a depth

A contractor can responsibly tell you the depth range nearby wells needed, the minimum construction the drilling area requires, and how the price changes with depth. Nobody can honestly tell you in advance exactly how deep your well will be or how many gallons per minute it will produce. If a quote does, ask what happens when the ground disagrees.

After the well is drilled

Once the well's record is in WIMS, the next buyer or neighbor can see what your well found. Keep your own copy with the property paperwork, and test the water: Missouri's health department recommends testing at least once a year. ^[5]

Have a property in mind? Call us with the location and what the water is for.