Located about 100 miles from the Gulf of Mexico, New Orleans had hoped to avoid the ecological disaster currently affecting much of the Mississippi and Louisiana coasts. This weekend, however, researchers discovered tar balls washing up onto the shores of Lake Pontchartrain, the ecologically delicate 630-square mile body of water that constitutes the city's northern flank. (See a video of oil seeping into the lake.) What does this latest development mean for the beleaguered Big Easy? A concise guide:

How did oil get into Lake Pontchartrain?
Despite lines of barges and miles of booms set to block the flow of oil, high winds from last week's Hurricane Alex blew crude into the lake through the narrow Rigolets inlet that connects the lake to the Gulf of Mexico.

How much oil has entered the lake?
Relatively little, so far. Since Monday, clean-up crews have gathered nearly 2,000 pounds of oil, or less than 100 barrels (4,200 gallons). With oil still spewing into the gulf, however, experts say subsequent hurricanes could drive thousands of more gallons into Lake Pontchartrain. The unusually complex wind and current patterns of tropical weather raise the risks, says John Lopez, director of the Lake Pontchartrain Basin Foundation.

What will be the environmental impact?
Although experts predict minimal impact to the lake's ecosystem, Lopez has raised concerns about the blue crabs, shrimp, and fish that migrate into the lake to breed. His group is seeking $7 million to fund a five-year study to monitor the impact.

How is New Orleans handling this?
Because Lake Pontchartrain is mostly used for recreation, the presence of crude in the water and on the shores could deliver a psychological blow to the area's residents. "People love the lake, and they live around the lake," Lake Pontchartrain Basin Foundation executive director Anne Rheams tells the Los Angeles Times. The oil's arrival is "really bringing [the disaster] closer to home for our folks in the basin."

Sources: Washington Post, CS Monitor, L.A. Times, AOL News