After being out of the state for more than a week, I returned to find that the Delta — the heart of California’s water system — is still at the center of public attention. Perhaps that shouldn’t be a surprise, because there’s no shortage of problems facing our local waterways.

Most have been well-publicized: We know that the Delta smelt and other native species are rapidly declining. A lack of water flow in the river, giant pumps that collect water for export, invasive species and toxic runoff from farm outfits are all possible culprits.

We also know that there’s just not enough of the Delta to go around. The San Joaquin River, for instance, is so diverted that it runs dry in places, especially in the eastern Central Valley. And continued pressure from Southern California water consumers means that farms and fish in the valley never get as much water as they want or need.

When the rainy season hits, the levees that keep rivers from flooding homes and businesses are in such poor repair that it’s an annual event to guess which will hold and which will break. Many cities, counties and developers make matters worse by continuing to build in natural flood zones.

To top it all off, the state released a study this week that confirms what most casual observers already figured out: pollution in the Delta is a serious problem. Tracy even showed up on the report, as the nearby Grant Line Canal is evidently a hot spot for DDT — a testament to the staying power of the pesticides we use, considering DDT was banned more than three decades ago.

Just as there’s a laundry list of Delta problems, there’s no lack of competing interests that make finding a solution difficult.

Environmentalists want to restore the river to a more natural, healthy state — one in which flows from the headwaters actually reach San Francisco Bay — and recently helped shut down the pumping stations that send water south to protect the few remaining smelt from being sucked up.

Farmers, meanwhile, are arguing for more reliable water delivery, which means that the pumps will stay on and that the San Joaquin River will likely stay dry. Some, including the Western Growers association, support a peripheral canal that would have water diverted around the Delta directly into the state’s pipes and aqueducts.

Recipients of Delta water in Southern California, including the teeming millions in the Los Angeles Basin, are only concerned that water keeps flowing south.

For those with a Delta river or slough as a neighbor, levee strength and flood control is the priority.

With all that, what is a state to do?

Gov. Arnold Schwarzenegger suggests spending $5.9 billion as a cure-all remedy, including expanding surface storage, restoring habitat, maintaining levees and building the controversial peripheral canal that was soundly defeated by voters in 1982.

It’s good to see the governor offer a solution, even if it’s short on money and long on promises. But to create a plan that will make the Delta healthy again, some serious compromises need to be made.

Environmentalists no doubt would challenge plans to build new reservoirs or expand existing ones and will continue to protect local endangered species through litigation. But they must also realize that with California expected to add 25 million residents by 2050, securing more fresh water is a necessity. Something has to give here. Building desalinization plants along the coast would mitigate that need and would require relatively little energy, but that’s another column.

Farmers, while defending their obvious need for water to grow our food, can’t ignore the fact that their operations seriously degrade the amount and quality of water flowing through the Delta.

Ever-expanding Southern California will have to make due with less, even if a peripheral canal robs the Delta of more water and sends it south.

Local governments will have to learn to say no and provide other construction options to developers who want to build subdivisions in the shadow of crumbling levees.

And all of us who depend on the Delta — urban or rural, SoCal or NorCal, human or not — will have to learn to give as well as take.

While progress is being made — water consumption has decreased since the 1970s, responsible construction is gaining ground and farmers are more vigilant about what they release — there’s still a long way to go.

The problems facing the Delta are probably too complex to be solved by any single plan on the table. One thing, though, is certain: everyone can agree the Delta needs fixing, but it will never be done unless the competing interests learn to compromise.