"It Is Raining Outside!"

Greg Mumm 

May 2003

This month Greg was trying to decide what to write for his column and all he came up with was how happy he was it is raining outside. Which led to the subject of water and I asked if I could step in on land use.

On April 25^th, the Black Hills Regional Multiple Use Coalition brought in Hydrologist Janet Carter to share with us the hydrology study that was done in the Black Hills. The study was done from 1990-2000 as a partnership among several local, State, and Federal agencies. The purpose of the study was to assess the quantity, quality, and distribution of surface water and ground water in the Black Hills area. I never understood before exactly what aquifers were, and how water is stored in the earth. This was one of the best BHRMUC meetings I have ever attended. I now understand why some of the creeks run above ground and others below ground. The aquifers are layers of earth that store water. We learned what affects them, how, and where they recharge. We also learned how water temperatures affect the quality of the water, and I also learned how lucky some people who live in the hills are to have wells that last.

The major aquifers in the BH region are the Deadwood, Madison, Minnelusa, Minnekahta and the Inyan Kara. The highest priority was placed on the Madison and Minnelusa, which are widely used and interact extensively with the surface water resources in the area. There were 71 observation wells and two cave sites used during the study. The study looked at affects of climate, pumping, and long-term water levels. One of the most interesting things found was that despite drought and water usage the aquifers always seem to recharge themselves. The lowest water levels ever measured were in the late 30’s. There was somewhat of a drought in the 60’s, the later 80’s showed a slight decline and throughout the 90’s the recharge was at it’s highest. Unfortunately the study ended in 2000 so there was no indication on how the latest dry spell and the fires may have affected the ground water but I feel much more confident that we are not going to dry up and blow away.

The largest user of ground water is the pine tree, which drinks an incredible amount of water daily. Once I get my Black Hills water study atlas I can give you a firm estimate as to what that amount is but I think its in the order of 65 gallons a day per tree.

One of the alarming things I learned was that the largest contamination of ground water comes from septic tanks. The same regulations for septic tanks are used throughout the state and now that I am an informed citizen I will support stricter regulations for Black Hills septics.

The combined water volume for the aquifers in the study area is estimated to be 10 times the water volume of Lake Oahe. The temperature of ground water affects its quality, the warmer the water the more stuff it dissolves into it.

The Madison aquifer is very visible throughout the Black Hills in the form of our beautiful limestone cliffs. Once I get my new Atlas I’ll bring it to one of the meetings and let you take a look. Water can be very interesting and it is also a necessity. Additional information concerning the study and study products is available at http://sd.water.usgs.gov/projects/bhhs/BHHS.html.

I am praising God for the rain that is at this moment pouring down from the sky to soak into our parched earth. It has put a smile a mile wide on my face because we are going to get to wheel this summer.