SANTA ROSA -- Nearly 660 staff nurses at Santa Rosa Memorial Hospital went on strike Tuesday morning at Sonoma County's biggest hospital as the St. Joseph Health-owned facility and the union representing the nurses, Staff Nurses' Association, failed to reach agreement on a number of employment-related issues.

The strike will last from Tuesday at 5 a.m. through Thursday, according to the union and hospital officials. All but four nurses with the union voted to not strike and about 125 nurses picketed the hospital this morning.

St. Joseph Health said it would remain open during the picketing with contracted nurses. The agency representing the replacement nurses required a four-day contract, meaning the union nurses would return to work on Sunday, Oct. 6, according to the hospital.

At issue for the striking nurses is "substantial decreases" in shift differential and a 10 percent decrease in night-time pay, the union said in a release. The union also said the hospital is proposing what it called a "crippling loss" for on-call pay from 30 percent to 50 percent. Differences also exist between the two sides on health benefits, overtime pay, paid time off and scheduling issues.

The hospital, which said it has not encountered a nursing strike since 1986, said it "worked diligently" to avoid a strike. The hospital also said the union's latest proposal of a 10 percent wage increase over two years is "significantly out of line with current economic trends confronting U.S. health care providers as reimbursements decline sharply under health care reform."

The union, however, said nurses at Memorial, which includes the region's level II trauma center , are 5 to 15 percent behind most local and Bay Area hospitals in wages.

St. Joseph Health has proposed a 2 percent raise over two years, the union said.

"The hospital's pay and benefit package is not competitive and risks the hospital's ability to retain and attract nurses," the union said in a release.

Debra Miller, vice president of human resources for Memorial, said in a release that the administration sought the best deal it could given the economy and health care landscape.

"We're very disappointed that we could not come to a mutually acceptable agreement with the union, and look forward to resuming negotiations soon on behalf of our valued nurses," Ms. Miller said. "We are committed to providing just wages and benefits to our registered nurses."