Textbook costs should drop for Washington college students next fall after the state Senate passed a bill Tuesday requiring publishers to disclose prices and revisions to faculty.

Gov. Christine Gregoire is expected to sign the measure into law after the House passed the bill last month.

Students pay an average $900 a year for books and course materials, according to WashPIRG, a nonprofit lobby group that backed the legislation.

Publishers often make minor changes between textbook editions, such as tweaking the colors on a graph or correcting grammatical errors, said Bryce McKibben, the student-body lobbyist for the University of Washington.

When faculty know how small the changes are, they can approve older versions of the same textbook.

That allows students to buy secondhand textbooks for half the price of new editions, McKibben said.

And while quality remains the primary consideration for faculty in choosing among texts, McKibben said, they will now be able to offer students cheaper books in cases where there are two competing books of similar quality.

There was little opposition to the bill in the Legislature — nobody testified against it, although the Association of American Publishers sent a letter to bill sponsors expressing concerns and suggesting changes.

Only Connecticut has a similar law, according to WashPIRG.

McKibben said that students from the state's six public universities helped push the legislation

"We're very excited that it was so quickly drafted and heard through both chambers," McKibben said.

"It's democracy in action, and I've really enjoyed the experience."

The bill was sponsored by Rep. Bob Hasegawa, D-Seattle.

Nick Perry: 206-515-5639 or nperry@seattletimes.com