Blog: Matthew Naud & Jamie Kidwell

Ann Arbor has had an energy office longer than most cities - and also happens to know where each of its 14,000-plus water pipes are located (many cities don't). Matthew Naud and Jamie Kidwell, key players in Ann Arbor's sustainability planning effort, will write about using these advantages and others to forge a new sustainability framework for the city.

Matthew Naud: Why the Huron is the cleanest urban river in Michigan

Time to share some sustainability stories – good stories about good people and good data.  
The Huron River is the "cleanest urban river in Michigan" – that's what they tell me and I'm sticking with it.  Thanks to the Clean Water Act (no matter your politics you should thank John Dingell if you see him) and the good work of the state's oldest watershed council, the Huron is our primary source of drinking water and an amazing recreational resource.  But it still has issues.  Too many nutrients (e.g., phosphorus (P) and nitrogen (N) from fertilizer and stormwater runoff) can overload the river chemistry and create environments ripe for algae blooms that are both ugly and potentially dangerous if they give off toxins.  The city is part of the Middle Huron Initiative – a partnership among the watershed governments – that is under a Federal mandate to reduce phosphorus loading to the river by 50%.

The city environmental commission, working with the Huron River Watershed Council back in early 2002, took look at what other communities and states had done to reduce phosphorus loading to their waterways.  Wisconsin and Minnesota communities had already undertaken local ordinances to limit phosphorus.  We had a creekshed study in Mallets creek that estimated a 20% reduction in P loading if we could limit P in fertilizer.  We had good soil sampling date from the MSU extension service showing that most of the soil samples in Ann Arbor did not need additional P to grow grass. 

We reached out to the commercial applicators and lawn and garden stores and heard two important messages – most commercial applicators were not using P in standard applications and the lawn and garden stores in the city just wanted to make sure that any regulation gave them plenty of time to get the right product on shelves.  After a couple of years of public process, a local ordinance was enacted in 2006 restricting the use of phosphorus in manufactured fertilizer and went into effect in 2007 to give local retailers time to get the right product mixes on the shelves.  The primary ordinance requirement was that fertilizer containing phosphorus only be applied when a soil test demonstrated that it was needed.  It also required that a pamphlet discussing the benefits of limiting phosphorus be provided at the point of sale and to commercial applicator clients.  We did not expect to do much enforcement and to date that has been the case.

So how do we know if it is working?  Often you don't.  Evaluating environmental programs can be difficult for two reasons – it is hard to design a good experiment with enough baseline data and if you can they are often very expensive sampling exercises.  In this case we were lucky (and kind of smart).  Lucky in that the Huron River Watershed Council and a University of Michigan faculty member had already been looking into nutrient loading on the river.  John Lehman at the UM had been sampling the Huron at several sites in previous years to look for causes and corrective measures for nuisance algal blooms on Ford and Belleville lakes.  Smart in that we asked him how we might evaluate the effect of the fertilizer ordinance.  Turns out you (if you are a smart statistician) can look at the variability in the historic levels of P in the Huron and the expected outcome (20% reduction) and develop a sampling frequency that will provide you with statistically significant results (if your estimated effect is correct). 

A graduate student undertook this sampling in 2007, 2008, and 2009.  They found that average reductions in total phosphorus at two city sites when compared to the baseline data show reductions ranging from 11-22%.  In a separate research effort, the Huron River Watershed Council is finding similar drops in P levels in area creeksheds, with higher drops in the urban creeksheds.   So…while it is hard to say that the ordinance "caused" the measured effect,  we haven't found a better explanation given both of these findings.  In July 2010, Michigan joined 15 other states in banning P in dishwasher detergents and in December 2010, Michigan passed a state-wide limit on phosphorus in fertilizer (PA 0299) that goes into effect January 1, 2012.  

So, after almost 10 years of work by a lot of good people using a lot of good data, we are seeing measurable improvements in our watershed and look forward to similar results across the state.  I think it's a good sustainability story.