The Los Angeles River is officially open for the summer. Now you can boat, fish, birdwatch and camp there through Labor Day, and some say this is only the beginning. City officials and the Army Corps of Engineers are working on a plan to restore the L.A. River and essentially turn it into a huge park. But a new report estimates it would cost the city more than a billion dollars. Is it realistic to hope that someday we’ll have a lush, green, 51-mile river teeming with life running through L.A?