Many West Contra Costa school district residents will be shocked when they open their upcoming property tax bills. The rate for repayment of school construction bonds will increase 30 percent from last year.

Blame the district's overly ambitious rebuilding program, wildly optimistic property value forecasts and failure to leave margin for unexpected events, such as the fire at the Chevron refinery in Richmond that dragged down its property taxes and left everyone else to make up the difference.

But most of all blame a deceptive school district political campaign over the past 15 years that convinced voters to pass six separate bond measures, never once telling them the cumulative effective of all that borrowing.

The biggest culprits in this charade are Trustee Charles Ramsey, who has made the building program his personal crusade-at-all-costs, and district superintendents, most recently Bruce Harter, who sign deceptive ballot tax rate statements.

School districts across the state carry on similar scams, but West Contra Costa raised it to a uniquely high level. In a 10-year period the district issued more bonds for school construction than any other K-12 district in the state except much-larger San Diego and Los Angeles.

They're not done -- not by a long shot. This year, district officials plan to issue another $125 million of bonds. And they can legally do it.

That's because West Contra Costa voters in elections from 1998 to 2012 gave the district permission to issue $1.6 billion of school construction bonds. So far, the district has borrowed $912 million and, after repayments, owes $718 million.

To pay the debt, the district tacks charges onto property tax bills. The amounts are determined in part by the total assessed value of property in the district. For years, district officials have claimed that total would rapidly rise, thereby keeping down the tax rate needed to pay off the bonds.

That hasn't happened.

In 2010, district officials forecast that the assessed value of all property in the district would increase 19 percent by now. Instead, it has declined 6 percent. Nevertheless, the district has continued to issue more bonds.

The result: Property owners last year paid about $216 for every $100,000 of assessed property value to retire school construction bond debt. This year, the rate will increase to about $282. Thus, the owner of a home assessed at $300,000 will pay $846. Forecasts show that rate will continue to rise.

District officials claim this is what residents wanted. But that's a difficult leap since voters were never told the full truth, or warned of the risks, before they voted.