CANTON, Minn. — Water shoots up from the hills of Vance and Bonnie Haugen's idyllic dairy farm here in a valley close to the Iowa border. That's why they named it Springside Farm in the '90s. Unfortunately, the nitrate shoots up here, too. Nitrate levels in the Haugens' water have steadily increased for the past 30 years, now ranging somewhere from 6 to 9 milligrams per liter of water every ...