In accordance with the 1991 settlement with the Hopi Tribe called an “Agreement Concerning Review of Certain Data” the Office of Surface Mining Reclamation and Enforcement (OSMRE) has reviewed and analyzed annual hydrological reports prepared by Peabody Western Coal Company (PWCC) and the United States Geological Survey (USGS). OSMRE’s review and findings are presented in the report titled Review and Analysis of Navajo Aquifer Material Damage Criteria for Peabody Western Coal Company’s Kayenta Mine Complex (OSMRE, 2023).
The review relates the data in the reports to the material damage criteria for the Navajo aquifer system (N-aquifer) found in the current cumulative hydrologic impact assessment (CHIA) of the PWCC Black Mesa Kayenta Mine Complex (OSMRE, 2016).
The material damage criteria were required by the “Stipulated Settlement Agreement of Appellants to Nizhoni Ani et.al. February 2012 Request for Review,” IV. Hydrology Claims: No. 2 which states:
OSMRE shall identify and adopt, as material damage criteria for the Navajo Sandstone Aquifer (“N-Aquifer”), numeric water levels that will be physically measured for all wells screened in the confined area of the N-aquifer that are monitored by the U.S. Geological Survey (USGS).
The PWCC hydrological data reports describe monitoring completed during calendar years 2020 and 2021 and includes summary data from previous years. The evaluation also considers the USGS 2016-2018 Report and USGS 2018-2019 Report, which provide the results of groundwater, surface-water, and water-chemistry monitoring in the Black Mesa area from November 2016 to December 2019.
OSMRE’s review and analysis of available information contained in PWCC and USGS reports from 2016 to 2021 indicates that material damage has not occurred to the hydrologic balance of the N-aquifer outside of the PWCC Black Mesa Kayenta Complex lease area as a result of mining and reclamation.