Environmentalists are optimistic that backers won’t have enough Senate votes to pass the bill. Meanwhile, President Obama has pledged to veto any such legislation that does make its way across his desk. But political winds shift quickly inside the Beltway, and only time will tell if the bill will gain enough support to withstand a veto. The quality of the nation’s water supply hangs in the balance.

CONTACTS: H.R. 2018, www.govtrack.us/congress/bill.xpd?bill=h112-2018; U.S. EPA, www.epa.gov; GOP.gov, www.gop.gov; National Wildlife Federation, www.nwf.org.