This report consists of three sections. First, in the background section, we describe (1) historical mining practices, (2) the risks AMLs pose to the environment and the physical safety hazards they cause, (3) the coordination across the many state and federal agencies to address AML issues, and (4) laws and programs governing the remediation of AMLs. In the second section of the report, we discuss key challenges to systematically remediating AMLs, such as a lack of a centralized statewide approach, land ownership issues, and lack of funding. In the third and final section, we recommend steps the Legislature could take to improve California’s approach to addressing the threats to public health and the environment caused by AMLs.