Saline contamination of soil and water on Pawnee tribal trust land, eastern Payne County, Oklahoma

The Bureau of Land Management reported evidence of saline contamination of soils and water in Payne County on Pawnee tribal trust land. Representatives of the Bureau of Land Management and U.S. Geological Survey inspected the site, in September 1997, and observed dead grass, small shrubs, and large trees near some abandoned oil production wells, a tank yard, an pit, and pipelines. Soil and bedrock slumps and large dead trees were observed near a repaired pipeline on the side of the steep slope dipping toward an unnamed tributary of Eagle Creek. The U.S. Geological Survey, in cooperation with the Bureau of Land Management, initiated an investigation in March 1998 to examine soil conductance and water quality on 160 acres of Pawnee tribal trust land where there was evidence of saline contamination and concern about saline contamination of the Ada Group, the shallowest freshwater aquifer in the area. The proximity of high specific conductance in streams to areas containing pipeline spill, abandoned oil wells, the tank yard, and the pit indicates that surface-water quality is affected by production brines. Specific conductances measured in Eagle Creek and Eagle Creek tributary ranged from 1,187 to 10,230 microsiemens per centimeter, with the greatest specific conductance measured downgradient of a pipeline spill. Specific conductance in an unnamed tributary of Salt Creek ranged from 961 to 11,500 microsiemens per centimeter. Specific conductance in three ponds ranged from 295 to 967 microsiemens per centimeter, with the greatest specific conductance measured in a pond located downhill from the tank yard and the abandoned oil well. Specific conductance in water from two brine storage pits ranged from 9,840 to 100,000 microsiemens per centimeter, with water from the pit near a tank yard having the greater specific conductance.

Bartlesville brine samples from the oil well and injection well have the greatest specific conductance, chloride concentration, and dissolved solids concentrations, and plot the furthest from meteoric water on a graph of 8 deuterium and d 18oxygen.

Waterflooding of the Bartlesville sand in the study area started in 1957 and continued until 1998. Waterflooding is the process of injecting brine water under pressure to drive the remaining oil to the production wells. The high dissolved solids concentration samples from observation wells 1, 3B, 5,7, and 8 could result from mixing of the Bartlesville brine from the waterfiood with meteoric water.