We propose installation of a detention basin in a small neighborhood (0.07 square miles) as a management technique to lower peak flows in the Los Angeles River and its tributaries by reducing urban and stormwater runoff. Reducing urban and stormwater runoff is a key factor in eventual improvements, such as removing concrete and planting native vegetation, that could be made to the Los Angeles River as part of the proposed Los Angeles River National Urban Wildlife Refuge (LARNUWR). Based on geographic information system data layers, county hydrology data, and on-site reconnaissance, we propose a design treatment that would help to reduce peak flows given a one-inch design rainfall. Our main goal is to determine the amount of space needed to capture the urban and stormwater runoff coming from a typical single-familyhome neighborhood in the LARNUWR. We calculated that our study area needs a detention basin approximately four percent of the size of the study area to capture and treat the runoff from the study area during a one-inch storm event.