"The Obama administration called Thursday for a comprehensive national system for regulating the use of federal waters along the nation’s marine and Great Lakes shores, now administered by a hodgepodge of federal, state or other agencies with often-conflicting goals."

"Runoff from all but the largest farms is essentially unregulated by many of the federal laws intended to prevent pollution and protect drinking water sources."

"Many urban streams have become salty enough to harm aquatic life, largely because of salt used for deicing roads in the winter, according to a new government study released Wednesday."

"Cleanup of the most polluted sites in the Great Lakes is moving so slowly it will take 77 more years to finish the job at the existing pace, according to a federal report."

"The federal government said Thursday that it would seek an unprecedented role as the environmental police of the Chesapeake Bay -- enforcing new rules on farmers and keeping a closer eye on state-level bureaucrats -- in an effort to halt the estuary's long decline."

"Caves are home to some of the planet's most unusual creatures and important drinking water supplies. Now these underground resources are being polluted by surface activities, ranging from sewage spills to old factories. Experts call the problem 'extensive and serious.' Mammoth Cave National Park in Kentucky, Crevice Cave in Missouri and Whispering Canyon Cave in Alaska are examples. 'People need to be aware that there’s a subterranean ecosystem and that what happens on the surface impacts these unique ecosystems in a very real way,' said David Culver, a biologist at American University."

"Crops are wilting in the countryside, and the capital's water shortage has turned dire as Mexico grapples with its worst drought in more than half a century."