Measuring Impact: Evaluating the Economic, Social, and Ecological Services of the City of Ann Arbor Greenbelt Program

Abstract

Purpose of Study This report details the findings of a Master’s project group for the University of Michigan’s School for Environment and Sustainability (SEAS). The project evaluated the Ann Arbor Greenbelt Program, a land preservation program that aims to protect farmland and open space around the city. The Greenbelt Program was created by the Open Space and Parkland Preservation Millage, which passed in 2003. As the Program approaches its 15th year, the Greenbelt Advisory Commission (GAC) requested an assessment of the ecological, social, and economic outcomes of the Program to date. This project focused solely on the portion of the millage funding that is used for the purchasing of development rights to properties outside the City of Ann Arbor limits. Ecological Impacts Through this section of the project, we produced the first Program-wide, quantitative inventory of land use for Greenbelt properties, and then used these classifications to complete a comparative runoff analysis. The manual land use classification using aerial photography was completed for all land within the Greenbelt Program as of June, 2017. Lands were classified into 11 different land use / land cover classifications, which were then summarized into five higher level classifications. In the resulting summary, 66% of Greenbelt land is in agricultural use, while 24% of land is forested. This inventory will inform GAC’s future property recommendations, by allowing the committee to target specific balances of agricultural land and natural spaces, according to Program objectives. The land use classification was used to complete a comparative runoff analysis. A baseline scenario, representing current land use, was compared against two hypothetical alternative scenarios. The first scenario represented hypothetical conversion of forest and grassland within the greenbelt to agricultural use, while the second represented complete development of Greenbelt properties into residential and commercial uses. The Long Term Hydrologic Impact Analysis (LTHIA) runoff model was then used to compare the potential effects of these three land use scenarios on runoff and nonpoint source pollution. Compared with these alternative scenarios, the current land uses, which have been preserved in perpetuity through Greenbelt Program’s purchase of development rights, provide significant benefits. Both alternative scenarios predict increases in volume of runoff into the Huron River. Each alternative scenario also predicts increases in pollutants posing risks to water quality and human health, including common fertilizing nutrients and heavy metals. Social Impacts This portion of the project focused on the social impacts that the Program has had on the local farming community and seeks to answer the following questions: How has the Greenbelt Program affected the local farming community in the Greenbelt District? How do Ann Arbor residents value and perceive the Greenbelt Program? To answer this question, data were collected through inperson interviews with landowners participating in the Greenbelt Program and survey responses from Ann Arbor property owners. Using a qualitative approach, these data were reduced into three major themes and then analyzed to understand the social impact of the Greenbelt Program: (1) promoting resilience for the local food system and agriculture businesses, (2) preserving a farming legacy and highly desirable rural characteristics of the townships surrounding Ann Arbor, and (3) 3 bolstering regional agricultural economics. We use a case study of the Drake Family Dairy, located in Lodi Township, to display these themes. Economic Impacts The final component of the project was directed at an economic benefits-costs evaluation of the program. Several approaches were considered to measure the benefits and costs of the Greenbelt Program. The approach of using a Contingent Valuation study to estimate the non-use, or existence, value of the Greenbelt was ultimately selected as the best approach. A survey with a Contingent Valuation question and questions regarding attitudes towards the Greenbelt was administered to 1,300 Ann Arbor households. There were 441 responses to the survey, a response rate of approximately 34%. An estimated median willingness to pay (WTP) per year for the Greenbelt Program’s continued existence was found to be $127.19 per household. This amount was generated using a parametric analysis on a double-bounded dichotomous choice Contingent Valuation question. Aggregating this amount and comparing it with the real costs of the Program (paid through property taxes), it was found that the WTP for the Program was greater than the Program’s costs. This conclusion continued to hold through several sensitivity analyses of the statistical model and approaches. Conclusions This project provided new insight into the ecological, social, and economic contributions of the Ann Arbor Greenbelt Program. We have demonstrated that the Greenbelt Program provides substantial benefits to both residents in Ann Arbor as well as residents in the neighboring townships. As the millage reaches its halfway point, the results from these studies can be used to guide future research and public outreach, strengthen regional funding partnerships, and bolster Program development.