Islanders might have to wait longer than anticipated for light rail trains to begin ferrying passengers across I-90 as the recession continues to squeeze state agencies’ budgets.

Faced with lower than expected revenue forecasts through 2023, Sound Transit may have to trim down its light rail plans, delay construction or cut current operations, which could affect the East Link light rail project that is scheduled to begin serving Mercer Island in about 10 years, according to agency officials.

Bruce Gray, a Sound Transit spokesperson, said the agency found out in August that its funding will probably be $3.9 billion or 25 percent less than originally expected because income from sales tax has dwindled during the recent economic downturn.

Though the Sound Transit board has not made any firm decisions yet about what this will mean for the light rail program, Gray said it will face some hard choices in a series of budget-planning meetings starting this September. By November, he said, Sound Transit should have a plan for dealing with the revenue shortfall.

“The board is going to have some tough decisions to make regarding our long-term budget,” he said.

“We feel like we’ve trimmed the fat off all the projects and we’re at the point now where the board will consider delaying or even cutting projects.”

will consider delaying or even cutting projects.”

Gray said this most recent forecast is down about $800 million from the long-term revenue shortfall predicted last year because the economy has been slower to recover than experts predicted at that time.

He said last year the board dealt with the reduced forecast by cutting down project reserves, which is back-up money put aside for a project in case something goes wrong. Also, Sound Transit has already cut administrative costs by freezing salaries and basically eliminating travel spending, Gray said.

Now, he said, the board has three basic options for cutting costs: put projects off or slow them down, cut projects altogether or run buses and trains already in operation less frequently to bolster agency savings.

He said it is too early to know exactly what will happen to the East Link project when the board makes budget decisions in the fall.

“There is a chance that we are seeing things going in the right direction, but the dip that we had between 2008 and now has been deeper and harder to recover from than anyone expected,” he said of the economy.

For now, he said, we’ll have to wait and see what happens, and, since project costs have not changed, there is a chance that the revenue forecast for Sound Transit could improve if the economy recovers faster than expected.

“I would just keep an eye out,” he said. “We’ll know a lot more this fall.”