Ann Arbor, Mich.-Phosphorus levels in the Huron River dropped an average of 28 percent after Ann Arbor adopted an ordinance in 2006 that curtailed the use of the nutrient on lawns, according to a study published by John Lehman, professor of ecology and evolutionary biology at the University of Michigan. “It’s one of those things where political organizations take the action because they believe it’s the environmentally conscious thing to do,” Lehman said. “But (to date) there’s been no evidence offered in peer-reviewed literature that these ordinances actually have a salutary effect.” Now Lehman feels such evidence exists, according to the study he published Aug. 14 along with UofM students Douglas Bell and Kahli McDonald in the journal Lake and Reservoir Management. Lehman said the paper shows that phosphorus levels in the Huron River dropped after Ann Arbor adopted an ordinance in 2006 that curtailed the use of phosphorus on lawns. Lehman and another student had been studying nutrient levels in the Huron River and two downstream lakes, Ford Lake and Belleville Lake, for a different research project, and were ready to extend their efforts when contacted by Ann Arbor’s environmental coordinator. “Right away, we started to see decreases,” Lehman said. After the first year of data collection, it was clear that phosphorus concentrations were lower after the ordinance was enacted than before. But did the ordinance cause the drop? Though that explanation seems likely, Lehman believes public education efforts and general increased environmental awareness among Ann Arbor residents may also have entered in.
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