Subsurface Geology of Arsenic-Bearing Permian Sedimentary Rocks in the Garber-Wellington Interval of the Central Oklahoma Aquifer, Cleveland County, Oklahoma

Abstract

The Central Oklahoma Aquifer is an important source of drinking water in central Oklahoma. The major formations making up the aquifer, the Garber Sandstone and the Wellington Formation, consist of fluvial sandstones interbedded with mudstones, siltstones, and conglomerates. Water from some wells has naturally occurring arsenic levels that exceed federal standards. Past work suggests that the arsenic is concentrated in water produced from sandstones isolated by finer-grained rocks. One strategy for remediation is to selectively produce water from low-arsenic zones and to limit water production from sandstones isolated by finer-grained lithofacies. This requires the development of a stratigraphic framework that defines the lateral and vertical distribution of arsenic-prone lithofacies. Mapping of lithofacies suggests that arsenic concentration is most closely associated with shaly sandstone distribution; based on the maps, there are two favorable areas for new water wells, and at least one area that should be avoided.