SACRAMENTO -- One of the state's most powerful unions could soon be weighing in on state water negotiations.

The California Teachers Association is expected to debate its position on a proposed multibillion dollar water bond at the union's regularly scheduled meeting this weekend in Los Angeles. It is unclear if the CTA's State Council will take a formal stance. But some members are worried about any borrowing that might take money from schools, said union spokeswoman Becky Zoglman.

"Anything that could impact the general fund ... is going to be a great concern to our members and educators across the state," she said.

Another union -- the SEIU State Council -- is already on record opposing a bond. Opposition from the CTA, one of the most powerful political forces in Sacramento, would likely influence lawmakers, especially Democrats.

Lawmakers are considering a bond in the range of $7 billion to $10 billion to pay for water projects such as dams, underground water banking and upgrades in the environmentally damaged Sacramento-San Joaquin Delta. A bond of that size would be the biggest water bond in state history.

A legislative hearing is scheduled for Monday on the bond and other proposed policy changes as Republicans and Democrats enter a critical phase of negotiations.

Senate Leader Darrell Steinberg, D-Sacramento, on Wednesday acknowledged the pressure from public employee unions. "They've expressed their reservation and I respect it, I understand it," he told reporters. "But I know how important fixing California's water infrastructure is to the economic well being of California."

Every $1 billion in general obligation bond borrowing costs the general fund $65 million per year for 30 years, according to the Legislative Analyst's Office. Education funding is protected by Prop. 98, which guarantees a certain amount for schools each year.

Democrats have tried to assuage union concerns by proposing a ceiling on the amount of bond funds that can be spent in the early years. But if the controls are too tight, it could turn off Republicans, especially those in the Valley, who want money for dams.