The Groundwater-level Observation Well Network

The Missouri groundwater-level observation well network sbury Observation Wells is a series of wells across the State of Missouri in which ground- Water-evel ydrograph Formation contacts and depths based on well log water levels are monitored in real time and periodically. The 29243 07/26/2012 07/26/2012 07/26/2012 Western Interior wells monitor the water levels in multiple key aquifers, such as 0 confining unit 10 Soil the Ozark aquifer in the Salem and Springfield Plateaus and the Plains Alluvial Plain aquifer in the South-eastern Lowlands. Group 100 As of 2018, 150 real-time sites are operated as a cooperative 105 effort between the Missouri Department of Natural Resources Daily average water level in Springfield Plateau aquifer Warsaw Formation 160 (MoDNR) and the U.S. Geological Survey (USGS; fig. 1). This Burlington– 200 Springfield Plateau fact sheet describes the network and well data from the network. Keokuk Limestone 235 aquifer Elsey Formation 275 NTION 300 hysiographic region Reeds Spring Spickard Formation Daily average water level in Ozark aquifer 375 Salem Plateau 400 Southeastern Lowlands Pierson Limestone confining

Springfield Plateau Ozark

Depth from surface, in feet 435 St Francois Mountains Northview unit Formation Real-time well 480 500 Warrensburg Wildwood

Cotter Dolomite Ozark aquifer

600 600

Jefferson City Dolomite Asbury 700

Figure 2. Stratigraphy, well construction, and water levels for the paired wells at Asbury, Mo. Modified from Missouri Department of Natural Resources, 2018 (https://dnr.mo.gov/geology/wrc/ Figure 1. Missouri groundwater-level observation well network groundwater/strathydrographs/asbury_combined.pdf). Dark gray and physiographic regions. Modified from Miller and Vandike, 1997. section of the well indicates casing interval and light gray section of the well indicates open interval. The MoDNR maintains the wells by regularly visiting each site. MoDNR personnel ensure that the equipment is operating properly and make manual water-level measurements to ensure 401444093442001Spickard that the data are accurate. MoDNR collects other well informa- 0 tion, such as total depth, casing depth, stratigraphy, and lithol- NTION ogy, and prepares figures that show water level in relation to ercentile class aquifer thickness and well construction (fig. 2). Further informa- 10 5 tion is available at https://dnr.mo.gov/geology/wrc/groundwater/ 10–24 gwnetwork.htm. 25–75 Data are transmitted from the wells by satellite and are 76–90 90 available from the USGS National Water Information System on 10 the world wide web in near real time. The USGS processes these Mean daily water level data, making corrections and ensuring that real-time measure- November 2016– ments agree with the manual water-level measurements. The 15 October 2017 USGS makes occasional manual water-level measurements at Mean monthly water level key sites. Statistics are computed so that recent groundwater in feet below land surface Depth to water, November 2016– levels can be compared to historical levels to assess trends. For October 2017 Nov. Dec. Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. example, statistics such as daily and monthly mean water levels 2016–17 and 25th and 75th percentiles computed for the observation well near Spickard, Mo., completed in the glacial drift aquifer show Figure 3. Depth to water, mean monthly water levels, and mean that 2016–17 water levels are among the highest in the 45 years daily water levels exceeding the 75th percentile of historical water of record for this site (fig. 3). levels for Spickard well, Mo., November 2016–October 2017.

U.S. Department of the Interior Fact Sheet 2019–3009 U.S. Geological Survey ver. 1.1, March 2019 Groundwater-level data have been recorded at some sites , the largest industry in Missouri, depends on for more than 50 years. These long-term data are critical for groundwater. During 2015, approximately 1,300 Mgal/d of understanding the aquifers in Missouri. Changes in groundwater groundwater was withdrawn for irrigation, and 16.1 Mgal/d was levels can be affected by natural and human-induced factors. withdrawn for livestock (Dieter and others, 2018). Agriculture Natural factors include precipitation, changes in river stage, can be greatly affected by droughts (fig. 5), and the observation drought, , barometric pressure changes, and tidal well network is valuable in assessing the effect and severity of effects. Human-induced changes are generally related to the droughts on groundwater supply. During the 2012 drought, many pumping of groundwater. wells in the network, such as the Ozark aquifer well at Wild- Parts of Missouri have an abundance of groundwater, wood, had a decline in water levels (fig. 6). whereas other areas lack a reliable groundwater source. Some wells in the network have had an overall decline (fig. 4) in 170 510 water levels during the period of record, such as the well near 500 Warrensburg, whereas some have had increases. 180 190 490 125 645 200 480 130 640 2012 Drought 88 above NAVD 210 470 135 635 water-level decline in feet below land surface Groundwater level, in feet Daily depth to water level, 220 460 140 630 2008 2009 2010 2011 2012 2013 2014 2015 2016 145 625

above NAVD 88 above NAVD ear 150 620 NTION in feet below land surface Groundwater level, in feet Daily depth to water level, 155 615 Daily mean depth to water level eriod of approved data 2002 2004 2006 2008 2010 2012 2014 2016 2018 Figure 6. Hydrograph showing groundwater-level decline during ear the 2012 drought in the Ozark aquifer well at Wildwood, Mo. NTION Daily mean depth to water level eriod of approved data References Cited eriod of provisional data

Figure 4. Hydrograph showing groundwater-level decline at the Dieter, C.A., Maupin, M.A., Caldwell, R.R., Harris, M.A., Ivahnenko, T.I., Lovelace, J.K., Barber, N.L., and Linsey, K.S., 2018, Estimated use of water in the United Ozark aquifer well at Warrensburg, Mo. States in 2015: U.S. Geological Survey Circular 1441, 65 p. [Also available at https://doi.org/10.3133/cir1441.] Groundwater is one of Missouri’s most valuable natural resources (Miller and Vandike, 1997). Many municipalities Miller, D.E., and Vandike, J.E., 1997, Groundwater resources of Missouri, in Missouri State Water Plan Series: Rolla, Mo., Geological Survey and Resource rely on groundwater as their primary source of water, and more Assessment, Water Resources Report Number 46, v. II, 210 p. [Also available at than one-third of the approximately 797 million gallons per day https://dnr.mo.gov/pubs/WR46.pdf.] (Mgal/d) withdrawn in 2015 for public supply in Missouri was Missouri Department of Natural Resources, 2018, Asbury Observation Wells: from groundwater sources (Dieter and others, 2018). Ground- Rolla, Mo., 1 p. water is critical for tens of thousands of rural residents, and self- supplied domestic groundwater withdrawal was approximately By David C. Smith 57.5 Mgal/d in 2015. Groundwater is important for many other industries in the State, such as agriculture, mining, and power For more information concerning this publication, contact: generation (Dieter and others, 2018). Director, Central Midwest Water Science Center U.S. Geological Survey 1400 Independence Road, MS-100 Rolla, MO 65401 (573) 308-3667 Or visit the Missouri Water Science Center Web site at: https://www.usgs.gov/centers/cm-water

Scott Kaden, R.G. Groundwater Section Chief Missouri Geological Survey–Water Resources Center P.O. Box 250 Rolla, MO 65402 Phone: (573) 368-2194 Fax: (573) 368-2193 Or visit the Missouri Department of Natural Resources site at: https://dnr.mo.gov/

Figure 5. Pivot irrigation in the Missouri Bootheel in the ISSN 2327–6916 (print) southeastern part of the State (left). Farmer inspecting the effects of ISSN 2327–6932 (online) drought on crops (right), photograph by Kelly L. Warner, USGS. https://doi.org/10.3133/fs20193009