Foraminifera are from 5 to 50 times more abundant in the general Hyperion outfall region than in unaffected areas of the shelf. Large live/dead ratios occur in central and outer areas of the shelf where the accumulation of authigenic minerals suggests little deposition; small ratios occur in basin areas where sediments are accumulating at the rate of from 38 to 145 cm/1,000 yr. Hyaline foraminifera are more than 8 times as abundant as arenaceous forms in the inner shelf area, on the outer edge of the shelf, and in the bathyal zone.Planktonic foraminiferal tests are most abundant in the bathyal zone, near the heads of submarine canyons, and near the Hyperion outfall system of Los Angeles. The area of major development on the outer edge of the shelf marks the entry way of incoming waters onto the shelf. Inshore benthic species are not influenced by the outfall; four dominant open shelf species exhibit marked increases in productivity, recorded in the accumulation of abundant tests under the main tracks of the effluent. A Bolivina acuminata group appears and shows a dramatic increase in abundance in going from the edge of the shelf into deeper waters. A Bolivina argentea group appears and becomes dominant below depths of about 400 m.