• In anaerobic conditions (absence of oxygen), as conditions worsen as more phosphates and nitrates may be added to the water, all of the oxygen may be used up by bacteria in trying todecompose all of the waste.• Under anaerobic conditions, the iron phosphate precipitates in the sediments may be released from the sediments making the phosphate bioavailability.• This is a key component of the growth and decay cycle. The pond, stream, or lake may gradually fill with decaying and partially decomposed plant materials to make a swamp, which is the natural aging process.