Understanding how Selenium (Se) leaching rates change over time is critical for predicting long-term water quality impacts and supporting regional-scale regulatory models. This presentation examines the evidence for declining selenium release from coal mine waste rock in the Elk Valley, integrating laboratory weathering data, regional monitoring records, and updates to the Regional Water Quality Model (RWQM).
The analysis tests whether observed selenium concentrations in the Elk River are better explained by constant or declining leaching-rate models. Results show strong alignment between observed river data and models that incorporate declining selenium release over time, supporting the inclusion of time-dependent leaching rates in regional predictions. The findings provide an important technical basis for long-term planning, mitigation evaluation, and regulatory decision-making.
