You gotta add in Wisconsin and Illinois too.
And Canada; and Montana; and North Dakota; and South Dakota; and Nebraska, and Wisconsin....not to mention Lake Superior. Of course, mallcontent and her agendized scientists have no common sense to figure out what streams outside of Iowa, feed Iowa's streams and rivers, throwing skew to any measurements of nitrogen leaving the state via streams and rivers. And, as proven, her totals amount to junk science anyway.
I like that mention of Lake Superior. How much of that water do you think adds to the stream flow in Iowa? Or the Gulf of Mexico?
Your geography is as bad as your math and science, or maybe worse.
Lake Superior drains through lakes Huron, Erie, and Ontario into the St. Lawrence River which flows northeast to the Gulf of St. Lawrence (not the Gulf of Mexico), and then into the North Atlantic Ocean. That's near Newfoundland, Labrador, New Brunswick and Nova Scotia.
If you're unfamiliar with Canadian provinces, it's just north of Maine. That's our most easterly state and one of the most northerly.
My map shows Lake Superior touching Minnesota, Wisconsin and Michigan, so no waters from this lake migrate southward? Is Lake Superior like a cement-enclosed swimming pool that is self contained?