This report determines the areal extent of saltwater intrusion into the alluvial aquifer in the vicinity of Brinkley in northern Monroe County, Arkansas. By definition, any chloride concentration greater than 50 mg/L is considered affected. The extent and magnitude of saltwater in the alluvial aquifer were largely determined through the collection and analysis of aquifer water-quality data. From 1946 to 1984, water samples were collected from 208 wells that tap alluvial water, 8 wells that source the Sparta Sand, 2 wells from the Cockfield aquifer, and one well each in the Memphis and Nacatoch aquifers. The majority of chemical data was collected during the period of 1974-1984. Numerous water level measurements were made during this same period.

The report includes

• Location map of observation and oil and gas test wells in the study area
• Generalized geologic column in the study area
• Discussions of the history of saltwater intrusion, and possible sources of contamination
• Contour map of the chloride concentration in the alluvial aquifer in the study area
• Piper quadralinear diagram of water from wells in the study area
• Plots of bromide, iodide, and boron versus chloride concentrations in the alluvial aquifer
• Discussion of water use and decline of water levels
• Table of descriptions of oil and gas test wells
• Map of potentiometric surface for the alluvial aquifer: Spring, 1984
• Attachment A contains water-quality data for 217 alluvial aquifer wells in the study area.

*Includes: 35 pages, 14 figures, 3 tables

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