sentences:  The loss of riparian habitat along the lower of San Juan Creek and much of Trabuco and Oso Creeks due to channelization has also reduced steelhead habitat.However, in 2003 the California Department of Fish and Game reported three sightings of steelhead in , immediately downstream of a drop structure that channels the creek beneath Interstate 5.In response, the Department of Fish and Game lobbied Caltrans to build a fish ladder at the structure, but it has not yet been implemented, due to concerns about structural stability of the I-5 bridge and the presence of a nearby natural gas pipeline.