About 150 of Waste Management's union drivers of recycling and yard waste trucks went on strike Wednesday in King and south Snohomish counties, stopping pickups at as many as 20,000 homes and businesses.

Picket lines went up at several Waste Management facilities, according to the Teamsters Local 117, the union representing drivers.

A different union, Teamsters Local 174, represents the drivers of Waste Management's garbage trucks, who are honoring the strike, as is allowed by their contract, said union spokesman Michael Gonzales.

Waste Management picks up garbage, recycling and yard waste in some parts of Seattle, all of the rest of surrounding King County, as well as south Snohomish County, not including the city of Everett, according to company spokeswoman Robin Freedman.

The company and the union had been negotiating for months. The union wants higher pay to match garbage truck drivers, who reportedly earn $9 more per hour than recycling drivers.

In June, Waste Management trained temporary drivers to help in the event of a work stoppage.

The company offered the striking drivers what it is calling its final contract offer in June: a six-year deal that would result in total compensation of $98,023 in the final year, Freedman said.

"We're deeply dismayed that this is the choice that the union leadership took. It was an unnecessary, disappointing move," she said.

Teamsters Local 117 has complained to the National Labor Relations Board about violations by the company including bad-faith bargaining, coercion of employees and threats of retaliation. The union is asking the company to return to the bargaining table, said Local 117 Secretary-Treasurer Tracey A. Thompson.

"Waste Management has forced this labor dispute through its blatant disregard of U.S. laws," he said in a statement.

Freedman said Waste Management customers should watch the company website for daily updates concerning their waste pickup. Customers who did not get recycling or yard waste pickup Wednesday were advised to put their cans away until their next pickup time, when they could put out double their usual load.