Montana in the National Ground-Water Monitoring Network
Monday, December 4, 2017: 3:50 p.m.
102 B (Music City Center)
John LaFave
,
Montana Groundwater Assessment Program, Montana Bureau of Mines and Geology
Thomas W. Patton
,
MT Bureau of Mines & Geology, Butte, MT
The Framework for the National Ground-Water Monitoring Network (NGWMN) calls for the use of existing state and local groundwater monitoring programs (SOGW, 2013). The Montana Bureau of Mines and Geology (MBMG) maintains a statewide groundwater monitoring network that collects water-level and water-quality data from Montana’s principal aquifers—including the heavily-developed Intermontane Basins aquifers and the less-intensively-developed, but widely-used Alluvial, Lower Tertiary, Upper Cretaceous, Lower Cretaceous, and Paleozoic aquifers. Montana’s network design is based on aquifer extents and development, and provides current data about long-term trends in groundwater storage and quality.
The MBMG shares data through its Ground Water Information Center (GWIC) website (http:// mbmggwic.mtech.edu/), and web mapping applications. Data also are available through web services hosted on ESRI’s ArcGIS Server or Geoserver.
The MBMG selected its NGWMN wells based on Framework Document and “Tip Sheet” guidance available from the NGWMN web page (http://cida.usgs.gov/ngwmn/learnmore.jsp). Candidate wells had at least five years of water-level record and a monitoring frequency of at least quarterly. Other criteria included the aquifer extent, groundwater development, flow system position, and monitoring well density.
The selection process identified 227 wells for inclusion in the NGWMN. Each well’s hydrograph was evaluated against local hydrogeologic and land-use data to assign it to a Background, Suspected Changes, or Documented Changes subnetwork. Most wells show little-to-no anthropogenic influence and became part of the Background subnetwork. Hydrographs with anthropogenic signals (Documented Changes subnetwork) showed:
- Seasonal irrigation recharge—mostly from the irrigated alluvial aquifers.
- Seasonal irrigation withdrawals—mostly from the irrigated intermontane basins and buried glacial aquifers.
- Long-term depletion—locally from the upper Cretaceous Fox Hills-Hell Creek aquifer system in eastern Montana.
Data from Montana NGWMN wells are available through the NGWMN Data Portal (https://cida. usgs.gov/ngwmn/).
John LaFave, Montana Groundwater Assessment Program, Montana Bureau of Mines and Geology
John LaFave has served as a research hydrogeologist with the Montana Ground Water Assessment Program for the past 16 years, working on groundwater resource evaluations across the state. He has a bachelors degree in geology from the University of Wisconsin at Madison and a masters degree from the University of Texas at Austin.
Thomas W. Patton, MT Bureau of Mines & Geology, Butte, MT
Thomas Patton is a Senior Research Hydrogeologist at the Montana Bureau of Mines and Geology. His research interests include distribution of hydrogeologic information via Internet resources and groundwater level response to long-term climate variability.
