Five glacial and four bedrock aquifers were delineated in Hanson and Davison Counties. The glacial aquifers, outwash deposits confined by as much as 275 feet of glacial till, are the Floyd, Plum Creek, Ethan, Warren, and Alexandria. The bedrock aquifers are the Niobrara, Codell, Dakota, and Sioux Quartzite Wash, and may be as much as 80, 350, 700, and 500 feet below land surface, respectively. The glacial aquifers averaged 13 to 40 feet in thickness and contain about 670,000 acre-feet of water in storage. Recharge to the Floyd and Plum Creek aquifers is from the Sioux Quartzite Wash aquifer and from fractures in the Sioux Quartzite. Recharge to the Ethan and Warren aquifers is from the Niobrara aquifer. Reported yield to wells from the Floyd and Plum Creek aquifers was as much as 1,000 gallons per minute. Predominant chemical constituents in water from the glacial aquifers are sulfate, calcium, and sodium. The bedrock aquifers averaged 40 to 110 feet in the thickness and contain about 11.3 million acre-feet of water in storage. The direction of water movement in the aquifers is to the northeast. The average reported yield from wells in the bedrock aquifers ranged from 1 to 75 gallons per minute. Reported yield from wells in the Niobrara aquifer was as much as 1,000 gallons per minute. Predominant chemical constituents in water from the Niobrara and Codell aquifers were sulfate, sodium, and calcium. Predominant chemical constituents in water from the Dakota and Sioux Quartzite wash were sulfate and calcium.
