B08_Solicitation_Attachment_2_-_26_2b_Figures_Maps.pdf

This document is a 2016 Groundwater Monitoring Report for Yellowstone National Park, prepared for the National Park Service Mammoth Supply Center in January 2017. The report documents baseline groundwater and surface water quality data collected from four wastewater treatment facilities (WWTPs) within and adjacent to Yellowstone National Park: Madison Junction, Old Faithful, Grant Village, and Fishing Bridge.

The monitoring program evaluated nine monitoring wells and two stream sampling sites at Madison Junction; wells and stream sites at the other three facilities. Data collection focused on water surface elevations, temperatures, specific conductance, nitrate plus nitrite concentrations, chloride concentrations, and total Kjeldahl nitrogen levels. Key findings include groundwater elevations ranging from 6,793 to 6,786.4 feet at Madison Junction with generally consistent gradients toward the Madison River; specific conductance values higher than prior years (ranging 125-1,495 μmhos/cm); nitrate plus nitrite concentrations exceeding Wyoming's 10 mg/l domestic water quality standard in wells MJ-8 and MJ-11; and chloride concentrations below the 250 mg/l state standard. The report presents multi-year concentration data tables (1974-present) and includes detailed maps showing well locations, groundwater elevations, conductance contours, nitrate/nitrite concentrations, and chloride concentrations across each WWTP site. This monitoring data supports environmental compliance and assessment of potential groundwater contamination from wastewater treatment operations in the geothermal region.