Phosphorous run-off into the Huron River in S.E. Michigan has become a serious concern. as this infographic illustrates. Lawn fertilizer is one of the primary culprits.  

The data shown in this infographic was the key evidence underpinning the City of Ann Arbor's ordinance to limit widespread use of high-phosphorous fertilizers within city limits. A property owner now must demonstrate a phosphorous deficiency in order to be allowed to use high-phosphorous, lawn fertilizer.