Wastewater treatment plants would be required to make costly upgrades to cut pollution while farmers would do so voluntarily under a long-awaited strategy meant to reduce harmful nutrients in Iowa waterways and the Gulf of Mexico.
Gov. Terry Branstad's administration released the 200-page strategy document Monday after years of study.
The U.S. Environmental Protection's in 2008 ordered 12 states along the Mississippi River to develop strategies to prevent nitrates and phosphorous from reaching the Gulf of Mexico, where the substances harm marine and plant life.
Iowa is one of the leading contributors of runoff, which comes from fertilizers and manure used in farm fields and wastewater and industrial plants.
For the first time, the 130 largest such plants would be required to take additional steps to remove phosphorous and nitrogen.