Several passive systems treating highly acidic mine drainage with elevated aluminum and iron will be visited. One site utilizes low-pH iron removal with a terraced iron formation. This is preceding a multi-stage acid neutralization system where a limestone pond is flushed into a settling pond followed by a mixed media vertical flow pond and wetland. A second stop will include a newly expanded system for a severely degraded discharge (>400 mg/L CaCO3 acidity). It uses solar-powered valves to flush two limestone ponds in series with settling ponds followed by a mixed media vertical flow pond and wetland.