Larry Schmahl just passed along two photos of a first-year Purple Gallinule taken along the San Gabriel River south of Whittier Blvd. by a local birder. It's a yellow-tan bird with bluish coloration on the flanks, all-white undertail coverts.
It was seen either yesterday afternoon or on a recent afternoon, from the west side of the river, presumably along the bikepath. The photos show a bird in dried smartweed (Polygonum) and grass, and wading in shallow water. Looks like late afternoon light, so maybe it emerges late in the day?
Best access may be from Pico Vista Rd. on the west side of the settling ponds, where you can get onto the bike path and head east to the river. A bike may be handy, esp. on a hot day like today. I just talked to Larry and some folks are already out there looking for it. You could also park at the Pio Pico House on the east side of the river. Either way, exit the 605 Fwy. at Whittier Blvd. and head west.