A new report examines 12 ideas for augmenting the river's flow, and not even the most audacious of the plans -- importing icebergs, for example -- has been rejected out of hand.

Bill Rinne, director of surface water resources for the Southern Nevada Water Authority, said he took two things away from the report: All options are still on the table, and none of them seem to provide the perfect solution.

"I don't see a real silver bullet," he said.

The report, paid for by the Southern Nevada Water Authority and compiled by an outside panel of experts, was delivered to Secretary of Interior Dirk Kempthorne last week.

Water managers in the seven Western states that share the Colorado will use the findings to help them decide which of the 12 options to pursue first and when.

Rinne said he expects those talks to begin before the end of the year.

The stakes are high for Nevada, which stands to receive the first 75,000 acre-feet of water created through so-called augmentation of the Colorado River. If expanded through reuse, that's enough water to supply more than a quarter of a million homes.

The report cost about $750,000 and took more than a year to complete. It evaluates options in terms of water quality, reliability, relative cost, projected water yield, technical difficulty, environmental concerns, and permitting issues.

Among the most cost-effective options is seeding clouds in an effort to increase snowfall at the headwaters of the Colorado River system. According to the report, cloud seeding could produce as much as 1.4 million acre-feet of additional water a year at a cost of $20 to $30 per acre-foot.

By contrast, some of the most expensive options considered in the report could cost $4,000 an acre-foot or more.

Rinne said the problem with cloud seeding comes when you try to quantify exactly how much additional water the process may have produced.

"There is always a debate about that," he said.

The report concludes that a significant amount of water, perhaps as much as 150,000 acre-feet, could be saved by removing salt cedar groves along the banks of the river and its tributaries.

Left unchecked, the nonnative plant could spread from its current range of about 300,000 acres to 600,000 acres by 2020, siphoning as much as 1 million acre-feet more from the river in the process.

Rinne said salt cedar removal is already "under way" or actively being pursued by individual river states. So is cloud seeding.

One of the most popular ideas for saving the Colorado River, ocean desalination, lands in the middle of the pack in terms of its cost and projected water yield.

The report estimates 20,000 to 100,000 acre-feet a year could be kept in the Colorado as a result of desalting plants built along the coast of California and Mexico.

That water would cost between $1,100 and $1,800 per acre-foot.

Water authority spokesman J.C. Davis said ocean desalination might one day prove to be a major source of water for California, but it is unlikely to provide major benefits on the Colorado as a whole.

He said the process is expensive, requires vast amounts of energy and produces a brine by-product that is difficult to dispose of safely.

The report calls for more detailed study of desalination of both ocean water and brackish groundwater in Arizona and Utah.

One of the wildest and most expensive ideas addressed in the document involves ferrying fresh water to California across the Pacific Ocean. That could mean the aforementioned iceberg harvest or the shipment of water, most likely from Alaska, by tankers or massive, towed water bladders.

Another possibility involves the construction of an undersea pipeline that would carry fresh water to Southern California from the Columbia River, hundreds of miles away.

"It does pass the straight-face test enough to where you have to look at it," Rinne said. "Look at our petroleum supply. We move that all over the place, and we've done that forever."

The report also considers the diversion of water to Colorado River tributaries from the Bear River in Utah, the Snake and Yellowstone rivers in Wyoming, and even the Mississippi River.

Ultimately, the panel deemed those projects too vast and complicated for detailed review in the report.

Rinne called the report "a very good and important first step" in managing the Colorado amid drought, climate change, and mounting demand.

He said Nevada is being given first crack at the water produced through the augmentation effort because it has the smallest "shortage buffer" among the seven Colorado River states.

Unlike Arizona and California, Nevada has no large agricultural base with river water rights that could be converted to urban use.

"And we obviously don't have an oceanfront," Rinne said, so in-state desalination is not an option.

As a result, Nevada is most at risk of outgrowing its comparatively meager river allocation or having its municipal supplies jeopardized by continued drought and shortage.

Las Vegas was little more than a dusty railroad stop when the Colorado was parceled out in the 1920s and Nevada wound up with a 2 percent share.

Today, the Las Vegas Valley is home to 2 million people and 90 percent of its water supply comes from the Colorado River.

Contact reporter Henry Brean at hbrean @reviewjournal.com or (702) 383-0350.