With the coronavirus spreading rapidly, several American Indian reservations in the Southwest are experiencing extreme water shortages, a problem worsened by poor water infrastructure.

Though no one denies the acuteness of the problem, what is in dispute is who's to blame. Activists and environmentalists in these communities say decades of water-intensive coal mining has caused a dramatic drop in their aquifer. But the company that ran these now-shuttered coal mines disagrees.

On this episode of Parts Per Billion, Bloomberg Law correspondent Tripp Baltz explains the effect this dispute is having on these tribal communities and why Congress may be about to step in.