By Julie Cart, Los Angeles Times

A federal report looking at trends in population growth, travel patterns and land use and their impact on the environment is predictably sobering.

With the U.S. population expected to grow 42 percent from 2010 to 2050, the report from the federal Environmental Protection Agency offers a glimpse into the crowded world we’re in now and how planners of the future might make decisions with less environmental harm.

Among the findings of the current situation: imperiled water supply with at least 850,000 acres of lakes, reservoirs, and ponds and 50,000 miles of rivers and streams soiled by stormwater runoff. Although vehicle emissions standards are more strict, that has been offset by a 250 percent increase in vehicle miles traveled since 1970.

In the same vein, transportation is responsible for 27 percent of domestic greenhouse gas emissions.

The report is an update of the agency’s 2001 study and suggests strategies such as clustering development around existing centers and near public transportation, encouraging mixed-use developments and designing streets that welcome bikers and pedestrians.