 It provides habitat for about 200 bird species, including 100 migrating species and 20 nesting species.The marsh helps to clean polluted runoff in San Diego Creek before it flows into the estuary of Newport Bay.Until the early 2000s, the area was heavily contaminated with the pesticides diazinon and chlorpyrifos, which were successfully removed from the creek after the Environmental Protection Agency implemented best management practices in the watershed.