What are the most important causes and sources of water quality impairments?
The failure of Iowa’s assessed waterbodies of all types to fully support their designated uses has been attributed primarily to nonpoint sources of pollution. These nonpoint source impacts include modification of stream habitat or hydrology and delivery of sediment and plant nutrients from agricultural sources to waterbodies. There are also natural causes, such as natural shallowness in lakes, which are responsible for some waterbodies not meeting designated uses. Point sources have been identified as contributing to water quality impacts on a relatively small number of the waterbodies in Iowa. This small number reflects the success of Clean Water Act programs to control municipal and industrial point sources. The majority of impacts to water quality of wetland and flood control reservoir acres has been attributed to nonpoint sources. For more information about nonpoint sources, please refer to Nonpoint Source Information.
