"MAYFLOWER, Ark. -- An ExxonMobil pipeline carrying tar sands oil from Canada broke open in Arkansas on Friday, spilling thousands of gallons of black diluted bitumen into residential streets outside Little Rock and forcing the evacuation of 22 homes."

"Despite some lingering anger over wood-burning rules, Bay Area air quality officials say a five-year burn ban has paid off for the region's 7 million residents."

"WRIGHT, Wyo. -- In Wyoming, folks call it the 'No Elk' plant, an $800 million project that -- once finished -- was meant to supply coal-fired power to 100,000 homes and support dozens of full-time jobs on the rolling prairie of northeast Wyoming."

"Exxon Mobil was working to clean up thousands of barrels of oil in Mayflower, Arkansas, after a pipeline carrying heavy Canadian crude ruptured, a major spill likely to stoke debate over transporting Canada's oil to the United States."

"GONZALES, Tex. -- In a dusty lot off the main highway in this South Texas town, Vern Sartin pointed to a collection of hose hookups and large storage tanks used for collecting wastewater from hydraulic fracturing jobs."

"TRAVERSE CITY, Mich. — Government regulators can try to halt construction projects at power plants if they think the companies didn't properly calculate whether the changes would increase air pollution, a federal appeals court ruled Thursday, marking the latest twist in a decades-long fight over the Clean Air Act."

"The Environmental Protection Agency will move ahead Friday with a rule requiring cleaner gasoline and lower-pollution vehicles nationwide, amounting to one of President Obama’s most significant air pollution initiatives, according to people briefed on the decision."

"Snow-surveying crews across the Sierra are seeing bad news up close this week. California has about half a snowpack."

"The Coast Guard has asked the Justice Department to investigate possible pollution violations by both the drilling rigs Shell used in its botched efforts to explore for oil last year in the Arctic Ocean waters off the northern coast of Alaska."