Additional Article Content

• Figure 1 2005 electricity use in Santa Rosas water and wastewater systems
• Figure 2 2005 GHG emissions from Santa Rosas water and wastewater systems
• Figure 3 2005 energy costs for Santa Rosas water and wastewater systems
• Figure 4 2005 unit GHG emissions from Santa Rosas water and wastewater systems
• Figure 5 2005 water-related GHG emissions from Santa Rosas urban water cycle
• Figure 6 2005 water-related unit GHG emissions from Santa Rosas urban water cycle
• Figure 7 2005 water-related energy costs for Santa Rosas urban water cycle
• Figure 8 2008 electricity use and potential reductions for Santa Rosas main reclaimed wastewater pumps
• Figure 9 2008 installed cost and potential savings for Santa Rosas main reclaimed wastewater pumps
• Figure 10 GHG reductions from high-performance end-use efficiency and residential solar
• Creating a Greenhouse Gas Inventory
• Acknowledgements

Several organizations in different countries have proposed rules for calculating greenhouse gas (GHG) emissions. The GHG Protocol is one of the most widely used international accounting tools creating GHG inventories for government and businesses, and its definitions will be applied in this paper. The GHG Protocol accounts for direct and indirect emissions within a given government jurisdiction or corporate boundary, which are defined as the GHG Inventory.

However there are often large GHG emissions by outside entities that provide goods and services to a government agency or business, that are not counted in the GHG inventory. This occurs very frequently in the urban water cycle, where there are jurisdictional separations between water wholesalers, water retailers, sanitary districts, end-users, and reclaimed wastewater irrigators. The reason for tracking total GHG emissions beyond those reported in the GHG inventory is that it helps identify much larger and very effective regional opportunities to reduce emissions. For example, water efficiency might result in only relatively small reductions in GHG emissions—and costs—for a water retailer, but very large reductions for end-users and wholesale water suppliers.

Most GHG emissions related to water are from energy use. Several collections of comprehensive sources of information needed to estimate GHG emissions related to energy have been recently published, including one that focuses on water/wastewater systems. These details were considered and applied to the cases presented in this paper.