THE campaign for King County Proposition 1 says 600,000 hours of Metro bus service would be cut if voters don’t approve the measure.

At best, that’s disingenuous. The facts matter when asking voters to increase car tabs from $20 to $60 and to raise the sales tax 0.1 percent on the April 22 ballot.

In fact, Metro has known since at least March 13 that better-than-expected tax collections would reduce the expected cut down to 550,000 hours. That’s because King County’s trampoline rebound from the Great Recession netted Metro $5.4 million more last year than had been projected. Metro is now forecast to receive $13.7 million more in 2014 and $15.9 million more in 2015.

Metro General Manager Kevin Desmond cautions that a sudden economic collapse — such as the 2008 start of the recession — could render those forecasts meaningless. The previous downturns drained Metro’s reserves.

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Desmond acknowledges the 600,000-hour service cut is being revised downward. “Whether it’s 550,000 hours or 500,000 or 450,000, time will tell,” he said.

Despite the increased revenue, King County Executive Dow Constantine’s administration has decided not to update the list of routes to be reduced or eliminated should Proposition 1 fail. Instead, it’s sticking with the outdated chart, and won’t update it until after the April election.

That chart — and the 600,000-hour figure — have been the backbone of the pro-Proposition 1 campaign. It was distributed to The Seattle Times editorial board two weeks after the better-than-expected March revenue forecast was known.

The yes campaign is based on the-sky-is-falling rhetoric, and the truth is not so politically convenient. The truth is that Metro’s budget deficit is shrinking. That diminishes, even incrementally, the need for Proposition 1’s $1.6 billion, 10-year tax package.

King County needs to be straight with voters.

Editorial board members are editorial page editor Kate Riley, Frank A. Blethen, Ryan Blethen, Sharon Pian Chan, Lance Dickie, Jonathan Martin, Erik Smith, Thanh Tan, William K. Blethen (emeritus) and Robert C. Blethen (emeritus).