Slow-moving, warm water combined with nitrogen and phosphorus in the Saylorville Reservoir upstream on the Des Moines River, north of Des Moines Water Works’ treatment plant, have created harmful algal blooms for several years, causing unhealthy public beaches. Additionally, the blooms have exacerbated microcystin levels in the river, making treatment difficult or even impossible; the utility has to avoid the Des Moines River altogether for several months each year. Image courtesy of Des Moines Water Works.
