Characterization of vadose zone and assessing enhanced recharge potential in canyons and headwater areas of Western San Fernando Valley, California

For its water needs, the City of Los Angeles relies on imported water (the Colorado River, Owens Valley/Mono Lake Basin and the State Water Project) and local groundwater resources. In particular, the City on average gets about 15% of its water from the San Fernando Valley Groundwater Basin (SFVGB). In order to prolong and to enhance the groundwater resources of the SFVGB, several spreading grounds, which are located in the valley floor areas, have been developed since the 1930s. The existing spreading grounds are mostly located in the central and north central areas of the valley floor where alluvial units and fans are thick and rich with sand and gravel deposits. As the City's demand for water has increased and the availability of imported water has been constrained, and in order to impose less stress on water resources and ecology of the areas where water has been imported from. support in capturing and utilizing local water resources (e.g. treated wastewater recycling and enhancement of groundwater recharge rates using local runoff waters) has been increased in recent years. Specially, water availability and its quality and potential for enhanced recharge activities in over twenty XII canyons associated with upper portions of the Los Angeles River was initiated in 2005. The canyons are located within the mountainous and hilly areas of Western San Fernando Valley. Based on geologic settings of the canyons, several infiltration tests using double ring infiltrometers, soil sampling and its characterization and comprehensive water quality data collection, it has been determined that the potential for artificial recharge in some canyons is warranted.