The words “gridlock” and “Congress” have become predictable neighbors in many a sentence about the federal government.

But every once in a long while, something like this happens:

A bill to protect the environment was introduced in the House in March. In early December, the House passed the bill. A week later, the Senate passed it as well, without changing a word and by unanimous consent, just before Congress left town on Friday.

That is the strangely charmed life of the Microbead-Free Waters Act of 2015, which sailed through Congress in an age when most legislation plods. The new law bans tiny beads of plastic that have been commonly added as abrasives to beauty and health products like exfoliating facial scrubs and toothpaste.

Under the law, companies will have to stop using beads in their products by July 2017.

The problem with the beads, as researchers have discovered, is that they slip through wastewater treatment systems and into waterways. Sherri A. Mason, an environmental chemist at the State University of New York in Fredonia, estimates that 11 billion microbeads are released into the nation’s waterways each day.