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Environmental Footprint Analysis

Environmental footprint analysis is an accounting tool that measures human demand on ecosystem services required to support a certain level and type of consumption by an individual, product, or population. Footprint methodologies estimate life-cycle environmental impacts from a narrower viewpoint than traditional life-cycle assessment. The environmental footprint methods described below can be classified into two broad categories of analyses: streamlined life-cycle assessments that use a single-unit indicator (e.g., carbon dioxide equivalents) and location-specific analyses (e.g., ecological footprint of a city).

A single-unit indicator does not mean that only one source or one piece of data is used. Typically, many different data are used but are converted to a single common unit, such as carbon or nitrogen. In this manner, single-indicator environmental footprint analyses are similar to economic tools that use currency as their single-unit indicator.

Ecological, materials, carbon, nitrogen, and water footprint analyses are common methods available for calculating environmental footprints.

Ecological Footprint

Ecological footprint measures the amount of land and/or ocean required to support a certain level and type of consumption by an individual or population. This measurement is estimated by assessing the total biologically productive land and ocean areas required to produce the resources consumed and mitigate the associated waste for a certain human activity or population.[152] Through the ecological footprint analysis, it is possible to estimate the fraction (or multiples) of land/ocean area required to support a specific lifestyle within a specific geographic area (country, state, city, etc.).

Environmental Footprint  Analysis

Materials Footprint

Materials footprint uses material flow analysis to estimate the total material and waste generated in a well-defined system or specific enterprise.[153] This method provides several useful indicators for measuring the mass of materials entering and leaving a defined system boundary, including domestic material consumption (e.g., per capita material consumption), total materials requirements (e.g., the measure of all of the material input required by a system, including direct and indirect material flows and imports), and material intensity (e.g., the ratio of domestic material consumption to gross domestic product).[154-156]

Carbon Footprint

Carbon footprint is the most developed of the footprint methods. It is a measure of the direct and indirect greenhouse gas emissions caused by a defined population, system, or activity. Carbon footprints can be calculated by taking an inventory of six greenhouse gases identified in the Kyoto Protocol: carbon dioxide, methane, nitrous oxide, sulfur hexafluoride, perfluorocarbons, and hydrofluorocarbons. Each of these greenhouse gases can be expressed in terms of the single-unit indicator, carbon dioxide equivalents (CO2e) or in normalized terms (e.g., CO2e per sales dollar, land area, or production unit).[157] CO2e is calculated by multiplying the emissions of each greenhouse gas by their respective 100 year global warming potential.[158]

Carbon footprints are categorized into Scope 1 (direct greenhouse gas emissions from fuel combustion in vehicles and facilities), Scope 2 (indirect emissions from purchased electricity), and Scope 3 (other indirect greenhouse gas emissions, e.g., waste disposal, outsourced activities, business travel, emissions from leased facilities).

The World Resources Institute and the WBCSD have developed a framework for greenhouse gas accounting that is widely used and serves as the basis for international standards such as International Organization for Standardization (ISO) 14064-1. [157, 159]

Nitrogen Footprint

Nitrogen footprint is a measure of the reactive nitrogen (e.g., nitrous oxides, ammonia, etc.) associated with a population or activity through agriculture, energy use, and resource consumption.[160] Nitrogen footprints are typically expressed in terms of mass loading per time (e.g., kg/year). [161]
Water Footprint

Water footprint measures the total volume of freshwater that is directly or indirectly consumed by a well-defined population, business, or product. Water use can be measured by the volume of water consumed (e.g., the amount evaporated and/or polluted in a given period of time) and is indicative of the water volume required to sustain a given population. The water footprint of a region is the total volume of water used, direct or indirect, to produce goods and services consumed by inhabitants of a region. An internal water footprint measures the consumption within a region for goods and services, while an external water footprint measures the embodied water used outside the region for goods and services. The water footprint is divided into three elements: blue (freshwater consumed from surface and groundwater sources), green (freshwater consumed from rainwater stored in the soil), and gray (the amount of polluted water, which is calculated as the volume of water needed to dilute pollutant loads to meet water quality standards).[162-165] A water footprint is a hybrid method that utilizes data from a single indicator, but also requires location-specific data to assess impacts from water use, which vary based on climate. For example, water-stressed or arid regions are more vulnerable to water shortages.

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How can Environmental Footprint Analysis contribute to Sustainability?

Assessing environmental footprints may help frame and inform sustainability discussions by providing a better understanding of the limitations of local resources to support social, economic, and environmental systems. Environmental footprint analyses also help summarize a complex array of environmental indicators into a single or small number of values so they are more useful for decision-making.

What are the main steps in an Environmental Footprint Analysis?

The main steps in an environmental analysis are dependent upon the specific analyses being used. Location-specific analyses, such as ecological and material footprints, are typically calculated using annual aggregate or statistical data.[166] For example, to evaluate the three elements of a water footprint (e.g., blue, green, and gray) it is necessary to compile location-specific data related to relevant water use. [167]
As another example, the calculations in the National Footprint Accounts, which report ecological footprint by country and for the world, are based primarily on internationally recognized data sets from the United Nations International Energy Agency and the Intergovernmental Panel on Climate Change, plus supplemental data from peer-reviewed scientific studies.[152] A complete list of source data sets is included in the Ecological Footprint Atlas 2010.[168]
No specific software is needed for any of the footprint methods, however, various spreadsheet and aggregated life-cycle inventory databases are available. Single-unit indicator footprint analyses commonly use data and methods from life-cycle assessment to calculate a single indicator (e.g., carbon, nitrogen, water).

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What are the strengths and limits of Environmental Footprint Analysis in a sustainability context?

Environmental footprint analysis has several advantages. Specifically, this type of analysis provides:

  • a single index that is easy to communicate and understand;
  • a means to quickly assess and compare a variety of products, populations, or activities;
  • an easy linkage of local and global impacts; and,
  • a tool for exploring the relationship between different impacts.

Limitations associated with environmental footprint analysis are in some cases typical of all modeling efforts. Aggregation can oversimplify impacts: how the aggregation occurs is typically not included as part of the tool application; the assumptions and proxies used to derive the footprint result are not always apparent; and, calculations can be affected by data availability and boundary issues. Additionally, environmental footprint analysis is a purely environmental indicator and does not directly address social or economic issues necessary to comprehensively measure impacts. Some social and economic information may be inferred, however, as the environmental footprint is depended on current aggregate social conditions that create demand in specific regions.

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How is Environmental Footprint Analysis being used to support EPA decision-making?

Environmental footprint analyses are currently being used in a limited manner to support EPA decision-making. In the Sustainable Energy Diminution Projects in Alaska, EPA and a number of state and regional organizations are partnering on several sustainability efforts with the objective of statewide energy use reductions.[169] An EPA partnership with the state of Connecticut used environmental footprint analysis to help develop a conceptual plan showcasing the benefits of incorporating a more sustainable approach to growth and development.[170] EPA Region 9 recently began a project that will include an ecological footprint analysis of California.[171] EPA’s WasteWise Program has developed an Office Carbon Footprint Tool, which organizations can use to estimate greenhouse gas emissions from business operations.

EPA is continuing to develop methods for understanding and reducing the environmental footprints of projects and policies. In particular, EPA’s footprint evaluation methodology is used to support green remediation and reduce negative environmental effects that might occur during the assessment and cleanup of contaminated sites.

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Where can I find more about Environmental Footprint Analysis?

  • Global Footprint Network Exit EPA Disclaimer provides more information about ecological footprint analysis. 100+ cities/regions and 200+ nations have assessed their ecological footprint, available on the Global Footprint Network’s website Exit EPA Disclaimer.
  • The Greenhouse Gas Protocol Exit EPA Disclaimeris the most widely used tool for greenhouse gas accounting.
  • The Water Footprint Network Exit EPA Disclaimer provides more information about water footprint, including examples of numerous water footprint case studies of products, corporations, and nations, as well as a global water footprint.
  • N-print hosts a website on nitrogen footprint analysis Exit EPA Disclaimer that provides an online calculator and average annual nitrogen footprints for a number of different countries.
  • The World Wildlife Fund International Exit EPA Disclaimer uses the ecological footprint in its communication and policy work for advancing conservation and sustainability, including the annual Living Planet Report.

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Illustrative Example of an Approach uisng Environmental Footprint Analysis

  • Quantifying Economic and Environmental Benefits of Green Planning in Connecticut                     
    Source: EPA Office of Sustainable Communities[170]

    Suite of sustainability tools: benefit-cost analysis; environmental footprint analysis; green engineering; collaborative problem-solving

    As more communities pursue sustainable planning and development, determining which approaches offer cost-effective economic, social, and environmental benefits may be part of the process for each community. In weighing options, predicting the value of various plans and approaches informs decision decision-making. However, many communities lack the resources to perform such analyses. The EPA Smart Growth Implementation Assistance (SGIA) Program provides contractor services to communities to facilitate sustainable planning and development. Communities awarded SGIA assistance then partner with teams of multi-disciplinary, national experts to assess the existing community, analyze options, and create plans for sustainable development. Connecticut's Capitol Region Council of Governments (CRCOG) received expert technical support from SGIA and also partnered with town municipalities, the Partnership for Strong Communities, University of Hartford, and American Farmland Trust. Together they developed the Smart Growth Guidelines for Sustainable Development and Design (PDF) (55 pp, 29MB) to support community siting, planning, and developing housing strategies that incorporate smart growth approaches and green building techniques.

    The town of Manchester, one community assessed as part of the CRCOG project, developed plans to integrate green infrastructure approaches into the redevelopment of a vacant and blighted 250,000 square foot community shopping center known locally as the Parkade. In partnership with EPA’s Region 1, the town quantified economic and environmental benefits of incorporating green roofs, stormwater retention systems, street trees, constructed wetlands, and parks into a mixed-use, mixed-income housing development slated for the site.

    Quantitative BCA results are provided in the report, “From Grey to Green: Sustainable Practices for Redeveloping a Vacant Shopping Center (PDF)” (30 pp, 24MB). It showed, for example, that if 75% of the roofs at Parkade were vegetated, they would absorb over three million gallons of rainwater, reducing the load on existing stormwater runoff sewer systems. Installing solar panels on 14% of commercial buildings at the site would offset all of those buildings’ energy costs. Property values could be 20% higher when located along parks.[248] The results of these and similar analyses help inform decision-making to determine how best to improve residents' quality of life while sustainably protecting nearby waterways.

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  • Sustainable Energy Diminution Projects in Alaska: Energy Audits 

    Sources: EPA Region 10 and Indian Health Services, Office of Environment Health and Engineering[169]
    Suite of sustainability tools: benefit-cost analysis; environmental footprint analysis; collaborative problem-solving
    In Alaska, geography makes sustainability a necessity. Residents require significant energy for transportation and heating, particularly in regions that experience minus 50°F for weeks at a time. Heating oil is costly to purchase and transport, and additional energy is required for many day-to-day activities, including keeping pipes warm to prevent freezing and maintain drinking water supplies.

    These challenges have sparked significant efforts to reduce energy use. Energy reduction projects in Alaska and the region must be sustainable in that they must improve economic, social, and environmental systems, and also provide a long-term energy supply. Solutions must function in harsh, hard-to-reach places where people often rely upon meager resources. Furthermore, the energy infrastructure must be maintained and repaired using as much local material and manpower as possible.

    Multiple partnerships play a role in implementing effective and cost-efficient changes. The Alaska Native Tribal Health Consortium, Indian Health Service, Alaska Energy Office, and the EPA are partnering on several sustainability projects that will lead to state-wide energy use reductions. Current projects are focused in three areas:

        • Sanitation (e.g., water supply, sewage treatment, energy related to water operations)
        • Health care facilities (e.g., design and construction planning)
        • Community-level facilities (e.g., energy usage in homes)

    Alaskan sustainability projects encompass many details in multiple areas of expertise, but the majority of the projects involve energy audits to support benefit-cost and cost-effectiveness analyses. In sanitation, energy audits examine the efficiency of existing pumps and boilers, heat loss from water tanks, and heat recovery from power plants to identify options for upgrades. Energy audits are also integrated into construction planning, particularly for hospitals and health care facilities, with a focus on LEED (Leadership in Energy and Environmental Design) certification for new buildings. For existing buildings engineers are redesigning insulation systems, and homes use live-feed energy usage meters to provide residents with real time information on energy use and savings.

    Sustainable social and environmental systems hinge on adequate supplies of energy to maintain a healthy quality of life. The high costs of energy sources and limited financial resources provide an example of a situation where sustainability efforts are directly motivated by economics, and BCA and cost-effectiveness analysis can provide useful analytic platforms.

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  • San Luis Basin Pilot: Regional Sustainable Environmental Management

    Source: EPA Office of Research and Development [259]
    Suite of sustainability tools: environmental footprint analysis; integrated assessment modeling
    EPA developed the San Luis Basin Pilot Project to measure the movement towards or away from sustainability at the regional level. [259] This sustainable environmental management effort sought to formulate and test effective long-term management strategies on a regional scale by measuring fundamental aspects of a system that characterize sustainability.

    In December 2006, EPA Region 8 in Denver, CO requested that EPA ORD provide assistance with sustainable land management in the San Luis Basin. This region, which includes the counties of Alamosa, Conejos, Costilla, Hinsdale, Mineral, Rio Grande, and Saguache, was growing in population, had scarce water resources, and was experiencing the effects of climate change. This project fostered collaboration between EPA ORD, EPA Region 8, National Park Service, US Department of Agriculture’s Forest Service, US Fish and Wildlife Service, Bureau of Land Management, local environmental organizations, and local communities.

    The multidisciplinary team was asked to establish and analyze a group of science-based metrics that would measure sustainability over a 26-year period using publicly available databases. Three fundamental aspects of a system that characterize sustainability were measured: its inherent order, the energy required to maintain that order, and the human impacts on the system. Four metrics were chosen to measure and characterize these aspects of the regional system:

    • Fisher Information, to estimate dynamic order or organization
    • Ecological Footprint, to characterize the environmental burden
    • Energy Budget, to compute the flow and conservation of energy resources through the system
    • Green Net Regional Product, to determine regional economic health.

    The results of the metrics reveal how each part of the system is moving toward or away from sustainability. This methodology can be used to monitor the overall stability of a system over time.

    This methodology proves to be an accessible and useful method for measuring regional sustainability. Since the initiation of the pilot, the project organizers have hosted a series of public meetings with local stakeholder groups and community members to actively involve them in the determination of the metric methodology. Such information will help planners and community members move toward a more sustainable path with their future decision-making efforts for their region.

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  • Green Remediation Pilot Studies in Region 9

    Source: EPA Region 9 [260
    Suite of sustainability tools: environmental footprint analysis
    Cleanup of a brownfield or Superfund site can be a time-consuming and energy-intensive process. EPA is pursuing the use of green remediation to reduce the environmental footprint of cleanups by reducing the energy use; emissions and resource consumption associated with all phases of a site remediation (remedy selection, design, implementation, and operation phases). EPA Region 9 conducted pilot studies (PDF) (40 pp, 1 MB) on three sites using the environmental footprint analysis methodology.[260] The three case studies were Romic’s East Palo Alto facility in East Palo Alto, CA; British Petroleum’s refinery property in Wood River, IL; and, the Travis Air Force Base in Fairfield, CA.

    Green remediation is the application of technologies and approaches that minimize a cleanup project’s environmental, social, and economic footprints with a goal of restoring and revitalizing the surrounding ecosystems. Site clean-up should be structured to improve both public health and ecosystem function, while simultaneously reducing costs and improving economic outcomes. The approach uses sustainability assessment tools to identify potential impacts that may have been discounted, or not included, in traditional assessments, and address those that occur on local, regional, and global scales. The approach strives to reduce (or remove) the need for ongoing management of remediation techniques by relying on green remediation practices. Green remediation should examine all aspects of the clean-up process and characterize a number of inputs including: minimize total energy use while maximizing the use of renewable energy; minimize all types of air pollution including criteria air pollutants, volatile organic compounds and GHGs; minimize water use and associated impacts on water resources; reduce, reuse and recycle material and waste; and, protect land and ecosystems.[261, 262]

    The environmental footprint of a cleanup activity may include the direct and indirect releases of contaminants, the consumption of raw materials and energy, and the production, collection, and disposal of wastes. Other social and economic considerations may include ongoing energy and maintenance, noise or visual nuisance impacts upon the community, or opportunities for employment of local residents.[263]

    In each of the case studies, three remedial alternatives for corrective action at the site were quantified in a footprint analysis. The remediation at Romic’s site in East Palo Alto involved in situ bioremediation of volatile organic compounds using injections of nutrients (cheese whey and molasses), pump and treat technology, or a hybrid implementation of the two technologies. The remediation for the BP site in Wood River, IL involved phytoremediation, leachate extraction, and re-grading of the landfill cap. Remediation alternatives for the Travis Air Force Base involved bioreactor and dual phase extraction for source area remediation, and a bio barrier and permeable reactive barrier for plume migration control.

    The case studies explore the level of detail needed to make informed decisions that reduce the environmental footprint of implementing a typical remedy and use new methods to:

    • Identify or develop appropriate and applicable footprint conversion factors for energy, materials, and services involved in remedy implementation;
    • Estimate footprints of up to 15 environmental parameters for implementing the remedial alternatives;
    • Estimate the footprint contribution from onsite activities, transportation, and non-transportation off-site activities;
    • Identify components of the remedial alternatives that significantly affect the footprint and other components with negligible effects; and,
    • Conduct a sensitivity analysis for variations in remedy design, conversion factors, or other input values.

    For each site, the results of the pilot study demonstrated the best remedy alternatives with the least environmental footprint.[264] Site managers can use the analysis to better understand benefits gained from the remedy selection and to quantify improvements.

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  • Economy, Energy, and Environment (E3) Projects in San Antonio, TX

    Source: EPA Office of Chemical Safety and Pollution Prevention[266]
    Sustainability assessment tools and approaches: environmental footprint analysis; green engineering
    In order to promote sustainable manufacturing and economic growth, EPA’s Office of Chemical Safety and Pollution Prevention supported E3: Economy, Energy and the Environment (E3) projects in San Antonio, TX. The E3 projects sought to provide small-to-medium sized American manufacturers with the necessary technical assessments and tools to improve floor processes and minimize waste generation. E3, a framework that evolved from the Green Suppliers Network, is a coordinated federal and local technical assistance program that provides technical assessments of production processes and training in lean manufacturing and energy management.

    The San Antonio E3 projects addressed a goal set by CPS Energy, a local municipally-owned utility, to reduce nine megawatts of electrical demand from San Antonio’s manufacturing sector by 2020. To achieve this goal, the utility collaborated with the Texas Manufacturing Assistance Center (TMAC) to provide training, resources, and tools to help local manufactures increase efficiencies in energy and material use. In these projects, manufacturing personnel participated in customized, hands-on assessments of production processes on the factory floor. The personnel were then trained at TMAC to use “lean and green” manufacturing and energy management tools to improve operations. After completing the training, manufacturers received a list of recommendations for streamlining their industrial processes, increasing profitability, and improving overall environmental performance.

    Other partners in the collaboration included the Department of Commerce’s National Institute of Standards and Technology’s Manufacturing Extension Partnership, EPA’s Green Suppliers Network, and the Department of Energy’s Industrial Technologies Program’s Industrial Assessment Center, based out of Texas A&M University. In 2009 and 2010, ten local companies, including heating, ventilation, and air conditioning manufacturers, bakeries, apparel manufacturers, and aerospace part manufacturers, participated in the program.

    As a result of the program, San Antonio’s manufacturing sector reduced energy demand by an average of 557 kilowatts per customer and energy use by over 2.9 million kilowatt-hours. These energy savings also yielded an annual reduction of 1,744 metric tons of carbon dioxide and annual cost savings of over $360,000. San Antonio’s E3 program has ongoing projects, with additional proposals pending. The program is now self-sustaining, funded by clients who benefited from the services and local utility rebates.

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  • Measuring Sustainability

    Source: EPA Office of Research and Development [272]
    Suite of sustainability tools: sustainability impact assessment; collaborative problem-solving; environmental footprint analysis; resilience analysis
    “There is no definition of good health; however, you know if your health is getting better or worse,” says Heriberto Cabezas, PhD, senior science advisor to the Sustainable Technology Division in EPA’s Office of Research and Development. Cabezas and colleagues Matthew Hopton, PhD and Matthew Heberling, PhD recently finished co-leading a collaborative pilot study designed to help scientists know whether the environmental health of a region is declining or improving. He and his research partners explored ways to measure and monitor whether a large area of south-central Colorado, San Luis Basin, has been moving toward or away from sustainability.

    The ultimate goal of the research is to provide information that will help decision-makers determine if a given region is in on a sustainable path.
    Sustainability is a simple but powerful principle that recognizes that the natural environment is the foundation for human survival and well-being. Achieving sustainability means creating and maintaining the conditions with which people and nature can coexist in productive harmony—conditions that provide people with social, economic and other benefits—today and in future generations. Developing the science and engineering that people need to move in that direction is the “true north” of EPA’s collective research and development efforts.

    As one can imagine, assessing and measuring something as broad as sustainability across a large area is a major challenge. To start, Cabezas and his co-workers sought research partners from a broad spectrum of disciplines. He assembled a multidisciplinary team with the capabilities and expertise to examine several fundamental components of an environmental system and how these components relate to key aspects of human well being, including social and economic factors.

    In the San Luis Basin, the team found an ideal research site for their pilot study. The area is large enough to require complex data collection and analysis, but somewhat limited in scope with easily defined, natural hydrological boundaries and a limited population (around 50,000). Large amounts of publicly owned land simplified access for data collection and environmental monitoring. In addition, government officials from EPA’s local Region 8 (mountains and plains) and the National Park service expressed support for the study. 

    Approximately the size of Massachusetts, the area contains seven counties, the Upper Rio Grande River Basin, the San Luis Valley, and the Great Sand Dunes National Park and Preserve.

    The team set out to develop a straightforward, affordable method to measure and monitor sustainability for the area. To do so, researchers set three primary objectives: (1) determine if existing historical data sets could be used to estimate sustainability at a regional scale; (2) calculate sustainability metrics through time (1980–2005); and, (3) compare and contrast the results they found to determine if the region is moving toward or away from sustainability. 

    Cabezas and the team utilized available environmental, economic, and social data to calculate sustainability across four different metrics (standards of measurement). Each metric provides insight into important sustainability measurements. The “ecological footprint” metric, for example, linked the total area of biologically productive land available with measurements of human consumption and waste generation. An aggregate calculation of how much “natural capital” is being used or conserved (the “Green Net Regional Product” metric) was another. The researchers used other metrics to explore aggregate measurements of energy flows and inputs (the “Energy” metric), and the overall stability and order of natural systems (“Fisher Information and Order”).

    Together, the four metrics provide information to answer basic questions central to determining sustainability: How well can a region cope with change? How healthy is it economically? Is its energy use self-sufficient? Is its human population causing ecological damage?

    An example of how using sustainability metrics can illuminate what threatens a region’s long-term sustainability is the snowpack found on the high mountains surrounding the San Luis Valley. “The existence of stored water at high elevations allows all of the geopotential energy of this water to be released in a short period of time, and in the process, it recharges the groundwater and maintains unique geological an ecological features of the valley like the Great Sand Dunes and wetlands. One consequence of this fact is that the natural and agricultural systems of the region are vulnerable to climate changes that affect the snowpack,” Cabezas and fellow co-authors point out.[259]

    When all their calculations where completed, the team found evidence that over time the area was slightly trending away from a sustainability. “The trend away from sustainability is slight, so our advice to the local community in the San Luis Valley and to EPA Region 8 was that while no immediate corrective action is warranted, plans do have to be developed to move the trend back to sustainability” explains Cabezas. “Action is being taken to do that exactly. The first step is the awarding of an EPA contract for a third party to work with Region 8 and the local community in the San Luis Basin to implement the metrics and methods developed as part of the project in local decision-making.”

    Now that the major part of the pilot has concluded, Cabezas hopes that an organization will step up to continue monitoring the San Luis Basin. The team has developed user interfaces and spreadsheets to calculate the metrics and is ready to provide any technical support that the community needs. “The next part of the project is to work with the public in developing a means of implementing these ideas into public decision-making,” he says.

    Cabezas and the team were recognized with the 2011 Science Award from the EPA Region 8 Administrator. “This was the first place anywhere that this work has been tried, so the project was the proof of concept,” says Cabezas. Following its success, a second project using Puerto Rico as a test site is planned under the leadership of Drs. Hopton and Heberling.

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