Restoring the aquatic biota in the upper Los Angeles River watershed
The Los Angeles River is one of three major rivers in the Los Angeles basin of southern California and covers over 2,135 square kilometers. Today, over 80% of the river is channelized and is home to over one million people. Our study focuses on assessing the current status of aquatic vertebrates within three tributaries of the Los Angeles River in the Angeles National Forest; Pacoima, Big Tujunga, and Arroyo Seco. Surveys were conducted from 2001-2013 to determine the current distribution of aquatic reptiles, amphibians, and fish. These data were compared to historic assemblages to evaluate the potential for future restoration in order to maintain the ecological integrity of the Los Angeles River watershed.
Across the three tributaries, we detected two species of native aquatic reptiles (two-striped garter snake and western pond turtle), five amphibians (California chorus frog, Pacific chorus frog, western toad, arroyo toad, and the California newt), and three species of fish (Santa Ana sucker, speckled dace, and arroyo chub). In addition we also detected many aquatic invasive species. When compared to historic assemblages, multiple species are currently absent from this watershed. Several of these species are State and Federally threatened and/or endangered, including the Sierra Madre yellow-legged frog (Rana muscosa), the California red-legged frog (Rana draytonii), and the unarmored threespine stickleback (Gasterosteus aculeatus williamsoni). In an effort to preserve and restore the ecological integrity of this region, USGS is working to understand the species needs in order to assist restoration efforts. Currently, USGS is involved in several restoration projects for the Sierra Madre yellow-legged frog, the California red-legged frog, and the unarmored threespine stickleback in Los Angeles County and would like to expand these programs into the Los Angeles River watershed.