Ground Water Geology 101
The saying goes we are what we eat.  I wish to stretch that bit of wisdom a tad further by saying we are also what we drink.  Here is another case where Geology affects our daily lives.

The water that we drink comes out of the ground most typically unless you handle bottled water in bulk, collect rain water or spend lots of money on small bottles of water.  I for one have always taken water for granted.  When I lived in Ohio, we had municipal water association that always supplied us with palatable “safe” drinking water from shallow wells in recent river sediments.  While in Jackson Hole, our subdivision had a public well in which the fractured Madison Limestone (Mississippian in age) supplied us with wonderful tasting cool water.

Here in southern Powder River County, I get my water out of the Fox Hill Sandstone (upper Cretaceous, 69 million year old marine origin sandstone).  While this water is wonderfully clear, not sulfurous and tasty, I have just recently discovered that it has not been very good for me. The sodium content in my water has kept my blood pressure up even though I have been religiously taking medication to lower it.  As an experiment a few weeks ago, I started drinking low sodium bottled water and immediately noticed a difference.  As a result of my experiment, I since have installed a fairly expensive Reverse Osmosis Filter and instantly have very low sodium water. My blood pressure is now normal and I suppose that I will eventually be able to reduce my dependence on blood pressure medicine. The expense was worth it!

Of course each well is a different, unique source of water and the quality of water will vary tremendously from well to well even from the same formation in the same area.  Contrary to popular thought, water does not flow in underground streams in this country but exists between the grains of sand in the massive sandstone formations that occur in this region.  Some of these sandstone beds occur over a huge area where as others may be very limited in their extent so the quantities of water available with any particular well vary greatly.  Artesian water is just water that rises above the surface because it is under pressure.  It may not be safe to drink however.  Additionally the mineral content of any particular well will also vary tremendously depending on the rock which the water has been in contact with for many hundreds of centuries.

Water is a universal solvent capable of dissolving almost any mineral that it comes in contact with over time.  Hot or acid waters may increase the ability of water to absorb minerals as well. Other contaminants can cause problems too.  Sulfurous water is typically the result of a well that has Sulfur Reducing bacteria contaminating your system.  It is not unusual for a drill rig to spread these bacteria from well to well.  These cause the rotten egg smell which is obnoxious and corrosive to various degrees.  Sulfur Oxidizing bacteria result in a dark slime that can clog pluming similar to what iron bacteria does. Iron bacteria causes the water to have a yellow, red or orange color.  Sometimes the odor will only be apparent after extended periods of non-use.  To treat these problems you should contact a local well contractor or the Division of Environmental Health for information on shock chlorinating this type of contaminated well.

How do we know how safe our water is for us.  The first step is to have it tested. The website  will have a comprehensive discussion and list of labs in Montana certified to test private well water samples. One of the most important and easiest test is for Total Dissolved Solids (TDS). It is a direct measure of dissolved salt in the water and is measured by the ability of water to carry electricity.  (This should be of immediate concern to people with elevated blood pressure that drink water from private wells in my opinion.)  Health Departments often check for bacterial contamination but chances are if you have been drinking your well water for years, you won’t get sick from drinking it more.  Only visitors to your ranch will pay the price for cattle hanging around your well head.  There are also tests for various heavy metals such as lead, chemicals such as nitrates and important substances such as fluoride which in the proper amount is good for your teeth. If you don’t know the quality of your water, I suggest you find out sooner than later.  I actually did not find out that our water was affecting my health by talking to a doctor or having it tested, I simply did an experiment that may have given me many more years to enjoy my health.

There is power in knowledge.