. Bulletin. Science. 20 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES in 100 - "«j i- O E 80 - i_ o -a 60 - o a. E 40 - CO »4- o *-< c 20 - <D O t- o Q. 0 -. Color Odor Oil Foam Trash Algae Category Fig. 2. Percent of storm drains that showed obvious signs of trash, algae, foam, colors, or oily sheens. pling was conducted by collecting a single composite sample that consisted of three grab samples combined over a 10 minute period. A second composite sample was collected 20 minutes later, and a third composite collected 40 minutes after the initial composite. Existing flow gages maintained
. Bulletin. Science. 20 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES in 100 - "«j i- O E 80 - i_ o -a 60 - o a. E 40 - CO »4- o *-< c 20 - <D O t- o Q. 0 -. Color Odor Oil Foam Trash Algae Category Fig. 2. Percent of storm drains that showed obvious signs of trash, algae, foam, colors, or oily sheens. pling was conducted by collecting a single composite sample that consisted of three grab samples combined over a 10 minute period. A second composite sample was collected 20 minutes later, and a third composite collected 40 minutes after the initial composite. Existing flow gages maintained by the Los Angeles County Department of Public Works provided flow information. Results Our survey of the Los Angeles River identified 127 storm drain outfalls. Of these, 105 were flowing and 87 discharged sufficient volume to sample for water quality. Seventy seven percent of the outfalls discharged directly to the Los An- geles River and remainder discharged to the major tributaries. Flow The majority of flow on September 10 and 11, 2000 arose from treated waste- water discharges from the three WRP on the Los Angeles River. A combined MGD comprised approximately 72% of the dry weather flow. Roughly MGD (14%) arose from discharges out of six of the seven tributaries that dis- charge to the Los Angeles River. The Rio Hondo tributary was not flowing at the confluence to the Los Angeles River at the time of sampling. Roughly MGD (13%) arose from discharges of the 66 storm drain outfalls that discharged directly to the Los Angeles River mainstem. Visual Observations The presence of algae and trash were consistently observed at the mouths of storm drain outfalls to the Los Angeles River (Figure 2, Table 1). The amount of trash varied from drain to drain with 23% of the outfalls categorized as having "dense" (>50% surface coverage). However, 70% of the outfalls had algae that exceeded 50% surface coverage). The presence of foam, oily sheens and odd col
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Keywords: ., bookcentury1900, bookcollectionbiodiversity, booksubjectscience
