OLYMPIA, Wash. -

Below-freezing temperatures this week are welcome by officials fighting an invasion of New Zealand mudsnails in Capitol Lake in Olympia.

The invasive species coordinator for the state Fish and Wildlife Department, Allen Pleus, says he'd been really pleased if even half the snails freeze to death. The water was lowered Tuesday to expose more of the shore where the snails live.

The Olympian reports the tiny snails -- the size of a grain of rice -- showed up in the lake four years ago and threaten native species

The National Weather Service says the temperature at Olympia dropped to 15 degrees Thursday morning.

Temperatures were below freezing across Western Washington and in the single digits in Eastern Washington. The coldest reporting station appeared to be Pullman at minus-3.