An environmental group is hoping to pressure lawmakers into considering legislation that would limit runoff of fertilizer from farm fields by setting state standards.
Environment Iowa is rallying at the Capitol Tuesday to deliver a petition with 5,000 signatures to Sen. Dick Dearden, a Des Moines Democrat who chairs the Senate Natural Resources Committee.
The group says city water treatment plants can't keep up with the record levels of nitrate flowing into rivers from farm fields.
Farm groups oppose standards or strict enforcement saying managing runoff on each farm is different.
The state recently rolled out a new nutrient management policy supported by state agriculture and natural resources officials and Gov. Terry Branstad that relies on voluntary farmer compliance.
Environmental groups say that approach won't work.