How to find a well log in Montana

What a well log contains

A Montana well log report is the official record of work done in a borehole, filed by the licensed driller. A complete one gives you:

• Total depth and the static water level measured at completion.
• The driller's recorded yield, with the test type and duration.
• Lithology — the driller's log of the material encountered at each depth interval.
• Casing, completion interval, and screen or perforation details.
• How the well was drilled, and the drilling company and driller licence.
• Location, elevation, and legal land description.
• The intended use of the well.

How to read the lithology column

The lithology log is the most underused part of the record. It is the driller's description of what the bit went through — clay, sand, gravel, shale, granite — interval by interval.

It tells you why the well is the depth it is. A log showing 40 feet of clay over saturated sand and gravel describes a completely different situation from one showing 15 feet of soil over 200 feet of shale. When you are comparing candidate properties, the lithology of nearby wells tells you what a driller is likely to encounter.

Reading logs critically

Well logs are records, not guarantees, and they vary in quality. Older logs can be sparse. Locations are sometimes derived from a legal land description rather than measured, which can put a well a quarter-quarter section away from where it is mapped — roughly 1,300 feet.

Well status matters too: a log for an abandoned or plugged well describes a hole no longer in service, and it should not be treated as evidence of current supply. Our comparable-well analysis excludes those records and downweights wells with imprecise locations, which is the kind of adjustment that is easy to skip and materially changes the answer.

Every well in our reports links to its log

We think the ability to check our work is a feature, not a risk. Every well in a property report links directly to its original Montana well log report, and every water right links to its official DNRC abstract.

If a figure in our analysis looks wrong to you, you can open the source record and see for yourself. That is the standard we hold ourselves to.