"We really need to get to specifics, technical liabilities and the political feasibility of projects," he said.
Connor heads the federal agency responsible for what he called the most litigated and fought-over resource in the country. He said data projects 2013 will be the fourth-driest year in the Colorado River basin over the past 100 years. Last year was the fifth-driest year on record.
The river provides drinking water, power and recreation for some 40 million people in California, Arizona, Colorado, Nevada, Utah, New Mexico and Wyoming. Its largest reservoirs Lake Mead near Las Vegas and Lake Powell near Page, Ariz. are projected to drop to 45 percent capacity by September, Connor said.
Mexico also has a stake in the river, and U.S. and Mexican officials signed a pact in November for new rules on sharing Colorado River water, including a deal that lets Mexico store water in Lake Mead. The deal provides for international cooperation to ensure that river water reaches the Gulf of California for the first time in decades.
Anne Castle, assistant interior secretary for water and science, called Tuesday's conference at a U.S. Geological Survey office near San Diego International Airport the start of a "next steps" process.
Castle said she hopes more ideas and practical solutions will surface to deal with shortages predicted by a study released by the bureau in December.
The report looked at supply and demand of Colorado River Basin water. It said that by 2060, with the Southwest's population expected to swell, the river won't be always able to serve all the residents, businesses, ranchers, Native Americans and farmers who rely on it.
"This 'next steps' process may serve as a template for the way to implement the analysis being done in all these basin studies," Castle said in a conference call. "Part of that is bringing together all the diverse interests that will be represented."
Castle said a Ten Tribes Partnership representative of Native American groups and several regional environmental advocates were expected to attend. Plans call for organizing a trio of work groups representing municipal, agricultural and conservation interests.
Jennifer Pitt, head of the Environmental Defense Fund's Colorado River Project, said groups including Western Resource Advocates, Protect the Flows and Nuestro Rio want to see more water banking, along with more efficient use of existing urban water supplies, the reuse of waste water, better watershed management and improved agricultural techniques.
"Communities that depend on the Colorado River for water supply or as the foundation of a $26 billion recreation economy cannot afford to wait," Pitt said in a statement.
Save The Colorado representative Gary Wockner said he also planned to attend.
When the Colorado River was tamed by dams and canal water allocations were made nearly a century ago, agricultural interests gained broad water and irrigation rights that helped transform California's vast arid Imperial Valley east of San Diego into one of the most productive winter fruit and vegetable, cotton and grain farming regions in the country.
Tension has grown in recent years along with the sprawl of thirsty cities including Denver, Los Angeles, Las Vegas and Phoenix.
The seven river basin states responded by forging agreements on allotments in 2003 and guidelines for sharing the pain of shortage in 2007.
Pat Mulroy, general manager of the Las Vegas-based Southern Nevada Water Authority and a delegate to Tuesday's meeting, called the issues facing river users daunting, but not insurmountable.
A key concern in southern Nevada is the water level of Lake Mead already marked in some places by 100-plus feet of white mineral "bathtub ring" showing the effect of years of drought. The reservoir is Las Vegas' major source of drinking water.
"These discussions aren't going to be easy," Mulroy said. "But the longer we have to work through some really gnarly issues, the better."
Tuesday's meeting comes two months after an annual report by the advocacy group American Rivers labeled the Colorado River the most endangered waterway in the nation. The listing drew an endorsement from Castle at the time for bringing visibility to the problems of drought and overuse.
Castle said Friday the Interior Department recently released $8.3 million for programs under the ongoing WaterSMART effort. The acronym stands for Sustain and Manage America's Resources for Tomorrow.