Sloughs, unlike swamps, usually have flowing water. During the warmer times of the year, sloughs may be completely dry; during the winter they usually have pretty good flow. They help to filter out pollutants and slow down the water to allow sediments to settle out, as well as providing flood water diversion and habitat for various wildlife especially adapted to the intermittent water supply.
The day we visited Kiefer Slough, it was alive with many insects, amphibians, waterfowl, and small mammals. These smaller denizens will make themselves scarce this summer but will be back in great numbers come next rainy season.