A COMMUNITY SCIENCE APPROACH FOR EVALUATING HISTORIC AND CURRENT METAL LOADINGS TO THE TAR CREEK FLOODPLAINS, OKLAHOMA: IMPLICATIONS FOR WATERSHED MANAGEMENT

Tar Creek in Ottawa County, Oklahoma flows through a former lead and zinc mining site that is now a Superfund Site, which affects its geochemistry and hydrology. Runoff from the above ground mine waste piles and drainage from the flooded mines both contribute heavy metals to the water of Tar Creek. Tar Creek then flows through the residential towns of Commerce, Miami, and North Miami where particles containing heavy metals are deposited along the floodplain. Tar Creek floods catastrophically and frequently, experiencing historic “hundred year” flooding in 2007 and 2019. The Grand River Dam Authority (GRDA) is seeking to relicense the Pensacola Dam, and raise the water levels further, which would exacerbate back flooding along the Tar Creek watershed. Our partner organization, the LEAD Agency, as well as other local and tribal stakeholders in the Tar Creek watershed, are organizing against raising the water level. We aim to understand the geochemistry of heavy metal deposition across Tar Creek floodplains in order to inform LEAD’s environmental activism.

Using a Community Science model, we collected samples over the course of two trips to Tar Creek in 2022 and 2023. Sampling sites were selected based on a combination of land use and previous flooding impacts, and at varying distances from the sources of mine waste runoff and mine drainage. All transects include surface soil samples and sediment cores, and many of the transects include tree cores and tree bark deposition samples. In order to chemically characterize these samples, we used FP-XRF (bark analysis), pED-XRF (bark, surface soil, soil core, and sediment core analyses), and LA-ICP-MS (tree core analysis). By integrating across space and time, we can understand how heavy metal concentrations on Tar Creek floodplains vary across flooding events, distance from the sources of mine waste runoff and mine drainage, distance from the creek, and grain size of the soil. With this data we can inform environmental activism and risk assessments.