Light rail is on the ballot this month in Clackamas County.

Michael Clapp / OPB

Work continues on the Portland-Milwaukie Light Rail Bridge.

The Portland-Milwaukie light rail line has been controversial south in Clackamas for years. On its face, this measure asks voters if they want to “spend certain county resources” on the project.

But what the measure will actually do is a big question.

The 7.3 mile Portland-Milwaukie Light Rail line is already under construction.

So, what is this late-in-the-game measure all about?

It asks voters in Clackamas County if a handful of steps in the light rail project should get county backing. Problem is, those steps are to “meet previous contractual commitments.” And the TriMet transit agency says those commitments mean the ballot measure would have “no impact.”

In a sense, the measure intends to reconcile two events from last summer.

First, TriMet let Clackamas County reduce its cash commitment to Portland-Milwaukie light rail, in exchange for other contributions to the project. Second, Clackamas voters passed a measure requiring voter approval of future light rail spending.

So this measure responds to both.

County policy advisor, Dan Chandler says voters are being asked to weigh in on those “other contributions” from the agreement with TriMet.

“One of those is funding street and signalization improvements around Park Avenue and Oatfield. The transfer of two small pieces of property for the line.”

One property is the size of a tennis court, or about 2600 square feet. The other is a little bigger.

The measure also involves what areas TriMet controls.

“And then the execution of what’s called a ‘continuing control agreement’ that allows TriMet to control areas of county streets and sidewalks that might be occupied by the light rail line.”

So, if Clackamas County voters say “yes,” it would green-light the property transfers, the control agreement, and spending on traffic lights and road improvements.

The answer gets a lot messier, when it comes to what a “no” vote would mean.

TriMet officials declined to be interviewed for this story. The agency issued a statement emphasizing the contractual obligation, and calling the measure “advisory.”

TriMet has already sued over the measure, which appears on the May 21st ballot.

County policy advisor Dan Chandler says if voters say “no” and county commissioners respond by trying to block those steps, then a judge will likely decide what happens.

Clackamas officials say if they hadn’t put the light rail question on the ballot, then project opponents would have sued the county.

This story originally appeared on Oregon Public Broadcasting.