About 475,000 residents, major sea ports and airports, thousands of miles of roads and rail lines, power plants and wastewater treatment facilities are at risk of flooding due to sea level rise, according to a new report from the State Lands Commission.

Using research from Scripps Institution of Oceanography, University of California, San Diego, and other sources, the Commission report pegs likely sea level rise at 16 inches by 2050 and 55 inches by 2100. Yet a Commission survey of ports, harbor districts, and coastal cities and counties earlier this year found that "the majority of respondents have not yet begun to comprehensively consider the impacts of sea level rise."

The Commission has jurisdiction over tidelands and the beds of navigable rivers, lakes, bays and estuaries. In many instances, especially along the coast, jurisdiction has been transferred to local entities, but the Commission continues to monitor uses. Based on the new report, the Commission is headed toward requiring future development and lease applicants to analyze the potential impacts of sea level rise.

Property rights advocates have raised concerns about the report because it assumes that Commission jurisdiction will creep up the coast as sea level rises. Thus, coastal landowners could lose both real estate and legal rights to sea level rise, according to an analysis by Nossaman attorney Howard Coleman, who is urging property owners to apply for permission to build structures that protect against sea level rise.

The seal level rise report is available on the State Lands Commission website, www.slc.ca.gov.