Many causes of pollution, including sewage, manure, and chemical fertilizers, contain "nutrients" such as nitrates and phosphates. Deposition of atmospheric nitrogen (from nitrogen oxides) also causes nutrient-type water pollution.

In excess levels, nutrients over-stimulate the growth of aquatic plants and algae. Excessive growth of these types of organisms clogs our waterways and blocks light to deeper waters while the organisms are alive; when the organisms die, they use up dissolved oxygen as they decompose, causing oxygen-poor waters that support only diminished amounts of marine life. Such areas are commonly called dead zones.

Nutrient pollution is a particular problem in estuaries and deltas, where the runoff that was aggregated by watersheds is finally dumped at the mouths of major rivers.

Just what I have been telling people for years. even people that use "organic fertilizers" can contribute to the pollution of our world. Too much of any nutrient, more the the plants can use adn more than any organic matter can "lock up" will simply flow out and contaminate our water supply, even manure.

Welcome to OG, Janelee!

Not only are these dead zones being created, but some excessively live zones - something that is bringing this problem to light here in NJ (and, I'm sure, elsewhere). There has been an overabundance of jellyfish in shore and especially in and near bay areas here, and people have often had to stay out of the water, or take the chance of getting stung. The jelly fish feed on small organisms, which, in turn, feed on the microscopic algae, which is increasing greatly due to the runoff of fertilizer. Sometimes it takes something like this to get people to respond, but my guess is that it only affects a few, and is in the news briefly, so most simply won't bother.

Dave