Mining has a long history of leaving behind environmental messes, and acid mine drainage (AMD) is one of the worst offenders. We’re talking highly acidic water loaded with toxic metals that can poison rivers, wipe out ecosystems, and make nearby drinking water unsafe for decades.

If you live in San Diego County, especially anywhere near Imperial Beach, you’ve probably heard the same story for years: raw sewage from Tijuana keeps flowing north, beaches keep closing, and nobody seems able to fix it.