NACWA Recommends Revisions to Greenhouse Gas Inventory

Mar 19, 2019

EPA Building(March 19, 2019) - NACWA submitted comments on March 14 regarding EPA’s Draft Inventory of US Greenhouse Gas Emissions and Sinks: 1990-2017.  The annual Inventory provides nationwide estimates for greenhouse gas (GHG) emission for different sectors, including wastewater treatment, and is intended to be used only for informational purposes. 

The wastewater treatment category in the Inventory includes publicly owned treatment works (POTWs), septic systems, and industrial wastewater treatment systems.  NACWA has reviewed and commented on the POTW emissions estimates in the Inventory since 2007, recommending revisions to more accurately characterize the sector’s emissions. 

EPA has made clarifications to the Inventory in response to NACWA’s comments over the years.  NACWA continues to recommend that EPA develop US-specific emission factors when appropriate, particularly for nitrous oxide emissions, rather than using the general factors developed by the Intergovernmental Panel on Climate Change (IPCC) for use worldwide. 

NACWA also recommends that EPA update some of its data sources, including the data for wastewater produced per capita.  The data currently used in the Inventory are 15 years old and represent only states in the Great Lakes and upper Mississippi regions.  Droughts and effective water conservation efforts have reduced wastewater flow in many areas of the US. 

The emissions guidelines developed by the IPCC in 2006 are currently being revised and updated, and this may result in improvements to the Inventory in future years.  Since the updated guidelines are not available for public review until they are published, NACWA will thoroughly review the guidelines once they are available.  Governments are expected to vote to approve or disapprove the updated guidelines in May, but the publication date is uncertain. 

Members with any questions can contact Cynthia Finley, NACWA’s Director of Regulatory Affairs. 

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