The city of Washington, District of Columbia (DC) will face flooding, and eventual geographic changes, in both the short- and long-term future because of sea level rise (SLR) brought on by climate change, including global warming. To fully assess the potential damage, a linear model was developed to predict SLR in Washington, DC, and its results compared to other nonlinear model results. Using geographic information systems (GIS) and graphical visualization, analytical models were created for the city and its underlying infrastructure. Values of SLR used in the assessments were 0.1 m for the year 2043 and 0.4 m for the year 2150 to model short-term SLR; 1.0 m, 2.5 m, and 5.0 m were used for long-term SLR. All necessary data layers were obtained from free data banks from the U.S. Geological Survey and Washington, DC government websites. Using GIS software, inventories of the possibly affected infrastructure were made at different SLR. Results of the analysis show that low SLR would lead to a minimal loss of city area. Damages to the local properties, however, are estimated at an assessment value of at least US$2 billion based on only the direct losses of properties listed in real estate databases, without accounting for infrastructure damages that include military installations, residential areas, governmental property, and cultural institutions. The projected value of lost property is in excess of US$24.6 billion at 5.0 m SLR.

This article discusses a study by the city of Lakeville, Minnesota, to evaluate alternative disinfection technologies that was driven by U.S. Department of Homeland Security concerns about risks associated with handling, storing, and using toxic chlorine gas. The study evaluated alternative disinfection systems for the city's water treatment plant, considering the plant's existing system, safety, security, cost‐efficiency, and finished water quality. The Lakeville study did not evaluate ultraviolet, ozone, chloramine, or chlorine dioxide systems because of site and cost constraints. The study focused on sodium hypochlorite (NaOCl), that provides residual protection but is safer than chlorine gas and less expensive than other alternative disinfection systems. Installing a NaOCl system would require the city of Lakeville to make few modifications to its existing system, and finished water quality would be similar to what is presently produced. The article discusses the advantages and limitations of using sodium hypochlorite, and provides comparisons of capital costs and annual O&M costs of chlorine gas, commercial sodium hypochlorite, and on‐site sodium hypochlorite generation. The article includes a total present worth analysis for a 20‐mgd sodium hypochlorite disinfection system.

What strategies can water utilities in the United States develop to maintain and rehabilitate an aging infrastructure when a primary source of funding ‐ revenue from public demand ‐ is on the decline?

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In December 2000, the US Environmental Protection Agency published the final radionuclides rule. The standard of 5 pCi/L for combined radium (Ra) 226 and 228 will affect more than 500 US systems and 1.4 million people in 177 cities in the Midwest. The best available technology for Ra removal includes ion exchange, lime softening, and reverse osmosis. However, hydrous manganese oxide and manganese greensand filtration is capable of removing up to 80% of Ra. For plants designed to remove iron and manganese by a manganese greensand filtration system, the cost of removing Ra is minimal. Results of pilot‐ and full‐scale studies are reported from Bellevue Sanitary District 1 in Brown County, Wis.; Knoxville, Iowa; Garretson and Elk Point, S.D.; Marcus, Iowa; and Savage, Lakeville, and Hinckley, Minn. Also discussed are the relationship between total dissolved solids and Ra removal and the disposal of water containing Ra, which is a major concern.