SACRAMENTO — The fate of a new water supply and management plan for California remained murky Monday despite a scheduled floor debate in the Legislature.

A package of bills intended to provide long-term solutions to California’s water challenges remained tangled up in parliamentary procedures and backroom negotiations, a reflection of how difficult it has been to find compromise on one of the state’s most intractable issues.

Republican and Democratic lawmakers have introduced competing bills that have similar outlines but differ on key points.

The discussions center on creating an independent mechanism to govern the state’s water supply, initiating a spending program for new water storage and conservation programs, and establishing environmental safeguards for the Sacramento-San Joaquin Delta, the heart of California’s water-delivery system.

On Monday, various water bills were slated for review by committees before being moved to the floors of the Assembly and Senate. By evening, the bills had not moved to the chambers, and it was unclear when they would, if at all.

Lawmakers are considering the complex water fixes in a special session, the third one called this fall by Gov. Arnold Schwarzenegger. A bipartisan agreement on how to upgrade California’s water supply and delivery system would be a major victory for Schwarzenegger, who has been pressing lawmakers to focus on the issue.

For decades, governors and lawmakers have been unable to find compromise on a way to expand and divvy up the vital resource. Farmers, municipal water districts, environmentalists and sport fishermen often have competing agendas that pull lawmakers in different directions.

The debate also has pitted Northern California, which receives most of the rain and snow, against Southern California, home to a majority of the state’s residents.

At the heart of the debate is the delta. The largest estuary on the West Coast, it provides fresh water to two-thirds of California’s residents and irrigates thousands of acres of cropland.

Its place at the center of the state’s water-delivery system has placed the delta’s ecosystem in peril, with the massive pumps that draw water south being blamed in part for declining fish populations.

The latest proposals from Democrats and Republicans address California’s water problems on two fronts:

— One set of policy bills would create a seven-member commission to oversee the environmentally fragile delta. It would mandate conservation and groundwater monitoring, while setting higher penalties for taking water illegally.

— The companion bills would authorize $9.4 billion in bonds to pay for new reservoirs and underground storage, water recycling programs, local water projects and delta restoration. The bond would go before voters next year.

Under the Democratic bills, money would be set aside for new storage without dedicating funding for specific dams.

Schwarzenegger, Republican lawmakers and farmers have pushed for strengthening the language to ensure that some of the money will go to building dams. The two most likely locations for new reservoirs are in the Sacramento Valley north of the state capital and in the Sierra foothills above Fresno. A third proposal would raise the height of an existing dam in the eastern San Francisco Bay area.

The Legislature’s nonpartisan analyst’s office said the bond’s cost could force the state to spend 10 percent of its revenue each year to pay off debt.

Placing the bond measure on a 2010 ballot requires a two-thirds vote in the Democratic-controlled Legislature and thus will need some support from Republicans, who are likely to withhold their votes until the legislation is shaped to their liking.