Algal blooms associated with elevated nitrogen and phosphorus (nutrient) loading to drinking water supplies can have myriad impacts that can lead to higher drinking water treatment costs. Certain types of algae can produce toxins that may be harmful to animal and human health; algae can produce compounds that cause taste and odor issues in drinking water; and algae can react with disinfectants to form harmful by-products. Anecdotal evidence suggests that treating drinking water for algae can be costly, yet few comprehensive economic analyses have been conducted to estimate costs.
In “A Costly Endeavor: Addressing Algae Problems in a Drinking Water Supply,” Cadmus drinking water experts describe a case study of the estimated costs associated with providing potable water from Lake Waco, a drinking water supply in Central Texas that has experienced recurring nutrient-related algal blooms for decades. From 2002 to 2012, the city of Waco incurred an estimated $70.4 million in costs to address tap water taste and odor problems. The total cost is attributed to upgrades to the drinking water treatment process (92 percent); nutrient-related watershed water quality monitoring (4 percent); increased treatment chemical usage (2 percent); influent and treated water monitoring beyond regulatory sampling requirements (1 percent); and increased energy usage related to the treatment plant upgrades (1 percent). The average cost for the city to provide tap water to residents exceeds the national average for similar sized treatment systems, and a higher proportion of their drinking water production costs are attributed to advanced treatment compared to the national average.
Since the costs analyzed in this study are not unique to the city of Waco, this study may help water resource managers and society better understand the costs associated with elevated nutrient loading and algal blooms in drinking water supplies.