Fly Fishing
As the population of carp grows in the Los Angeles River, urban fly fishing in the Glendale Narrows and Elysian Valley is becoming an increasingly common sight. Fly fishing aficionados such as the UrbanFlyVentures have thoroughly mapped the river bed, guiding fisherman and fisherwomen to the best spots for catching and releasing carp in the 10-15 pound range.
Fishing in the river is not a new occurrence, but in the past it was often done more out of necessity than for sport. If you walk down the Narrows near Atwater early in the morning or late in the afternoon you'll find men and children with ice buckets fishing for carp or tilapia under the bridges or among the rocks - a regular (and free!) meal for many in Los Angeles's working and immigrant communities.
According to a 2008 study by Friends of the Los Angeles River, the fish are edible and healthy within limits. The study even suggests that the river water is cleaner than that in the ocean.
Below is a slideshow with David Korty and Devon Tsuno discussing fly fishing along the river.