Groundwater Availability
 

Alluvium (Qa)
Topography
The alluvium forms narrow floodplains and underlies terraces. At least one well-developed terrace is present along the principal streams of the region.

Hydrology
Where sandy material is present, and saturated thickness great enough, the alluvium will yield more than 500 gallons per day to screened drilled wells. Water is soft or moderately hard; it may contain large amounts of iron at depth.

Breathitt Group (Pbu, Pbm, Pbl) (Princess Formation, Four Corners Formation, Hyden Formation, Pikeville Formation)
Topography
The topography of the Breathitt Group is rugged; sandstones form narrow valleys and cliffs or steep slopes on hillsides, and shales form wide valleys and moderate or gentle slopes on hills. Tops of hills and ridges commonly are capped by sandstone.

Hydrology
In the eastern half of Magoffin County, the Breathitt yields more than 500 gallons per day to most wells in valley bottoms and almost half the wells on hillsides, and smaller quantities of water to wells on hilltops. In the west-central part of Magoffin County, the Breathitt yields more than 500 gallons per day to almost half of the wells drilled in valley bottoms and less to wells on hillsides and hilltops. Sandstone yields water to most wells. Shale also yields water to many wells, and coal yields water to a few. Near-vertical joints and openings along bedding planes yield most of the water to wells. Waters are highly variable in chemical character. Salty water may occur at depths less than 100 feet below the principal valley bottoms.

Grundy Formation (contains Lee-type sandstone of the former Lee Formation) (Plc)
Topography
The upland of the Grundy Formation is highly dissected along its western margin in the northern part of Magoffin County, and is characterized by steep-sided ridges and cliffs 100 to 200 feet high. Some cliff-forming sandstone paleochannels have been cut through the Paragon Formation into limestone units of the Late Mississippian.

Hydrology
The Grundy yields more the 500 gallons per day to most of the wells drilled in valley bottoms. It yields more than 500 gallons per day to about half of the wells on hillsides and more than 500 gallons per day to almost three-quarters of the wells on hilltops. Sandstone is the principal aquifer, but shale yields water to some wells and coal to a few. Vertical joints and openings along bedding planes, best developed in sandstones, supply most of the water to wells. Intergranular openings yield water to joints, and probably directly to some wells. Perched and semiperched water tables are common. Waters are soft to moderately hard, and sometimes contain noticeable amounts of iron.

The U.S. Geological Survey's Hydrologic Atlas Series, published cooperatively with the Kentucky Geological Survey, provides hydrologic information for the entire state.

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