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Updating a Greenhouse Gas Inventory

Durango, Colorado

Featured image for the project, Updating a Greenhouse Gas Inventory


The Team


The Initial Challenge

Following an initial county-wide greenhouse gas inventory completed in 2008 using 2005 data, the team was challenged to create an updated greenhouse gas inventory for the City of Durango. The objective was to create an inventory using current best-practice methodologies that could be used to establish priorities for emissions reduction and be relatively easily repeated in future years to benchmark progress.


The Methods

The team began by reviewing the 2008 greenhouse gas (GHG) inventory for La Plata County alongside up-to-date inventories completed by comparable communities across the US.
In line with current best-practice, and to ensure the comparability and replicability of the inventory, the team decided to use the ICLEI – Local Governments for Sustainability (ICLEI) ClearPath tool to create an inventory compliant with the Global Protocol for Community-Scale Greenhouse Gas Emission Inventories (GPC).

Team members participated in online GHG Inventory training available through ICLEI which helped in the development of project scope and the approach for data collection. Once familiar with the inventory concept and scope, the team began drafting data requests for key stakeholders.

Where data was not available at the scale or level of detail required, estimates were made using best-practice guidance provided in the US Community Protocol for Accounting and Reporting of Greenhouse Gas Emissions (USCP). Data was entered into the ClearPath tool for analysis and reporting.

Inputs for the GHG inventory were provided by the City of Durango Utilities and Solid Waste Divisions, Durango-La Plata Airport and the City of Durango Transportation Department. Additional data was provided by La Plata Electric Association (LPEA), Atmos Energy and Phoenix Recycling. Data was also collected by team members using the Durango and Silverton Narrow Gauge Railroad Train (D&SNGR) online schedule.

Team members used standardized forms provided by ICLEI to request data from these entities. Data was then input into ICLEI ClearPath – an online software platform for completing greenhouse gas inventories.

In addition to direct activity data, GHG inventories require emissions factors to estimate total GHG emissions. For electricity consumption, the per kWh emissions factor was provided by LPEA. Where locally specific emissions factors were not available, ClearPath default values were used to convert activity data into emissions.

The team began meeting via conference calls and face to face meetings (River City Hall) in mid-July, 2018. We met throughout the fall, roughly once a month (1-2 hours), until a majority of the data inputs were completed. After the start of 2019, meetings were less frequent as Imogen focused on drafting the report for review.


The Results

Figure 1: Front cover of GHG Emissions Inventory Final Report

Through this project, the team delivered the following outputs:

  • City of Durango Community GHG Inventory in ClearPath
  • Public-facing report providing a summary and methodology of the inventory. The report also provides examples of existing or potential strategies to reduce emissions in each sector. The report is currently in draft form. Once finalized it will be shared with Durango City Council and the public as well as used to inform the development of goals and strategies for emissions reduction.

The project science advisors (Drs. Williams and Casey) were afforded a meaningful opportunity to help Imogen Ainsworth to create something valuable for their community. The project also helped to foster a stronger relationship between the City of Durango and Fort Lewis College, which could lead to future opportunities for students and faculty to collaborate with the City of Durango toward community relevant projects.

In addition to fostering lasting relationships with local scientists and Fort Lewis College, this project enabled the City of Durango to complete a community-wide GHG inventory without the expense of hiring external consultants.

Working with local scientists made it possible to share the workload of data collection and reporting and provided insight and support on data calculations and analysis. Furthermore, seeking external expert advice on the inventory will add legitimacy to the final product and make it a more powerful tool with which to influence decision making.

The Durango City Council and community members will be able to utilize this inventory and report to gain information about greenhouse gas emissions associated with residential, commercial, and municipal use of electricity and natural gas, transportation, as well as and waste water treatment and solid waste. Additionally, the Durango City Council and community members will find clear tips and guidance about how to reduce greenhouse emissions across all these sectors in the report.

While the data collection and analysis methods used in this inventory are fairly standardized thanks to the emergence of national and global reporting protocols, the specific data used will vary by community. Other communities considering a GHG inventory may learn from some of the data estimation techniques used in this project, or be able to identify sectors in which they need to seek alternative methods to estimate emissions.

Figure 2: Durango Community Greenhouse Gas Emissions Summary Infographic [draft]


The team attributes the following to the success of their project:

  • Imogen’s leadership, persistence, and organization. Commitment, open mindedness and expertise of Drs. Williams and Casey.
  • Collaboration and open dialogue
  • Use of a previously generated GHG Inventory for LaPlata County (2008) and reading example GHG inventories supplied by Imogen.

If they were to do this project again, a few things that they might do differently include:

  • A more explicit division (point person) of GHG emission areas. As it progressed, Imogen handled the bulk of all data requests and data entry into ClearPath.
  • Possibly request several years of data at a time to support a trend analysis over several, using directly comparable data (apples to apples).
  • Seek data-sharing agreements with partners to ensure availability of required data and facilitate the collection process.

For those seeking to embark on a community science project, the Durango team emphasizes keeping up good communication throughout the duration of the project.


Durango is a small city in the southwestern corner of Colorado and is home to close to 19,000 people—the most populous city in La Plata County. The city was initially settled to serve the San Juan mining district and while some oil and gas development remains in the surrounding county, tourism is now the dominant industry in Durango. An historic downtown and railroad, extensive year-round recreation opportunities and proximity to archaeological sites including Mesa Verde National Park and Chimney Rock National Monument, draw thousands of visitors to Durango every year.


In 2015, Durango City Council adopted a Municipal Sustainability Action Plan.  In 2017, the City attained certification under the STAR Communities program. Durango is also a member of the Colorado Compact of Communities, a coalition of cities and towns working together to scale up and advance climate action planning. Durango City Council identified ‘creating a higher focus on climate and sustainability’ as one of its top priorities and is committed to taking proactive steps to measure and curb its greenhouse gas (GHG) emissions. Many Durango residents have expressed support for city-wide sustainability initiatives.


In 2008, a baseline GHG inventory was conducted for La Plata County using data collected in 2005. In the years since inventory was conducted, the City has scaled up its sustainability efforts for both internal operations and in the wider community. However, no action has been taken to update the 2008 inventory or benchmark progress on emissions reduction. The city is now looking to update the inventory at the city-scale using the most recent data available. The new inventory will be used to set priorities for future actions to reduce GHG emissions throughout the city.

About the Community

Imogen Ainsworth is the Sustainability Coordinator for the City of Durango. She will be supported by the Assistant Director of Community Development, Nicol Killian. The community leads commit to engaging with the scientific partner on this project and providing strategic direction to ensure that the scientific assessment is in line with their needs for an updated GHG inventory. Through the procurement of necessary data sharing agreements, the city will obtain access to all data sets necessary to conduct the assessment. Imogen will also be using ICLEI’s online software ClearPath to conduct the GHG assessment.

Project Team

Community Lead

Imogen Ainsworth is Sustainability Coordinator for the City of Durango, Colorado. Since joining the City of Durango in November 2016, Imogen has worked on a variety of initiatives, including recycling and sustainability outreach, solar PV feasibility, Durango’s STAR certification and organizational resource use efficiency. She holds an undergraduate Master’s degree in Environmental Geography from the University of Bristol, UK and a Master’s in Geography and Natural Resource Management from the University of New Mexico. While studying at the University of New Mexico, Imogen met her now-husband and relocated permanently to the US in 2016 after gaining experience working on municipal and non-profit renewable energy programs in her native UK.


Scientific Leads

Joanna Gordon Casey, a Fort Lewis graduate, recently returned to Durango after earning a Ph.D. in Mechanical Engineering at the University of Colorado in Boulder. She has expertise in measurements of atmospheric trace gases and aerosols and is interested in engaging problems related to air quality, human and environmental health, energy resources and associated emissions, atmospheric dynamics and transport, atmosphere-ecosystem exchange, the global carbon cycle, and climate feedbacks.


Laurie Williams is a professor in the Department of Physics & Engineering at Fort Lewis College. She joined the college in 2004. Previously, she was a post-doctoral researcher at Los Alamos National Laboratory in the supercritical fluids experimentation facility. Laurie began her career as a pipeline engineer for Western Gas Supply Company and as an environmental consultant prior to pursuing her Ph.D. and transitioning into academia. She is a faculty adviser and co-director of the Fort Lewis College student organization Village Aid Project and has helped lead many projects to design and construct water systems, sanitation systems and other projects in developing countries such as Myanmar, Nicaragua, Ecuador, Laos and Thailand.

Laurie Williams is a licensed professional engineer in the state of Colorado.

Collaborating Organization(s)