That was the basic question underlying a presentation given by city finance director Bob Biles to Tacoma City Council members at today’s noon study session.

Part of I-1033, the Tim Eyman-sponsored statewide measure on this year’s ballot, seeks to cap revenues deposited into city and county spending plans based on changes in population and inflation. Any additional revenues would be put into a “Lower Property Taxes Account” used to reduce property taxes.

The long and short of Biles’ presentation? It depends.

“I cannot possibly forecast what our (population and inflation) growth will be,” Biles said. “But again, I think you see the impacts … could be fairly significant.”

In a powerpoint presentation, Biles provided estimated ranges based on historic growth trends of the measure’s potential “six-year impact” to the city’s budgets. The estimates ranged from losing about $10 million in revenues over that span during low-growth periods (+2.5 percent), to losses of $161 million during periods of high-growth (+6 percent).

Based on calculations of the city’s average inflation and population growth trends over the past 13 years (+2.7 percent), Biles added it would take until 2012 before the city’s General Fund revenues would return to 2007 levels (about $206 million — the high point in city budget revenues from 2005 to 2009).

The discussion over 1033 led to much confusion as to how the measure will (or will it?) affect previous voter-approved levies, including previously past bond issues in Tacoma for Emergency Medical Services and city police headquarters. Council members, the city attorney, the city manager and Biles invariably took turns offering their analysis of what potential impacts to previously approved levies would be, though no firm conclusion was drawn.

“The conversation you’re having right now is a good indication of the confusion and the lack of clarity of this initiative,” City manager Eric Anderson said.

Joining Biles for the presentation was Victoria Lincoln of the Association of Washington Cities, who told councilmembers current polling shows it’s a 50-50 toss-up as to whether the measure will pass — though only weeks ago, the measure was forecasted to win easy approval from voters.

Unlike it did for Referendum 71 at last week’s council meeting, the City Council will not officially vote whether it supports or opposes I-1033. Mayor Bill Baarsma said it’s “just plum too late” to get such a resolution on the council’s agenda before Election Day next Tuesday.

City spokesman Rob McNair-Huff said video of today’s I-1033 discussion should be posted on the city’s website within the hour.