Iowa agriculture provides tremendous benefits to the state, national, and global economy. The intense nature of the state’s agricultural activities is not without cost. Agricultural industry is a large contributor to water quality problems both within the state as well as in downstream rivers, streams, and the Gulf of Mexico. First released in November 2012, the Iowa Nutrient Reduction Strategy (NRS) lays out a technology-driven framework for reducing nutrient delivery to waterways in Iowa and, ultimately, the Gulf of Mexico. These efforts are part of a broader strategy that includes 11 other states to reduce the size, severity, and duration of hypoxia in the Gulf of Mexico.

While the Gulf Hypoxic Zone has received a lot of attention, meeting the NRS targets would also have large local benefits. Many water utilities and homes with private wells must treat their water due to high nitrate levels. In a recent court case, Des Moines Water Works (DMWW) unsuccessfully sued three Northwest Iowa drainage districts to compensate for its nitrate removal costs. According to DMWW, the utility spent over $500,000 to remove nitrates in 2016 and plans to expand its nitrate removal capabilities in coming years at an estimated cost of $15 million. Beyond the state capitol, water utilities across the state dedicate substantive resources to remove nitrates. Ensuring nitrates in drinking water remain low is imperative—high nitrate levels in drinking water are associated with adverse human health outcomes for susceptible populations. Beyond drinking water, nitrate pollution also contributes to the poor water quality of Iowa’s rivers and lakes, diminishing the recreational value of these resources.

This report explores important costs of high nitrates to Iowans and summarizes benefits to the state of meeting its NRS targets. 1 In Section 1, we discuss important factors that determine nitrate levels in the state’s streams, rivers, and lakes.2 We also provide background on drinking water sources in the state and existing nitrate regulations in the United States.

Section 2 explores nitrate removal costs to public water supply (PWS) systems and private well owners. We first summarize nitrate removal technologies, and their associated operating costs, that are available to PWS systems. Because many Iowans living in rural areas rely on private wells for their home’s drinking water, we also explore trends in nitrate levels in private wells and discuss treatment and avoidance costs to these households. We then provide three case studies of how towns in Iowa manage nitrates in their drinking water. We find that Iowa’s PWSs have invested at least $1.8 million in nitrate treatment equipment since 2000, that many small PWSs cannot afford to meet EPA safe drinking water standards for nitrates, and that many Iowans that rely on private wells are potentially exposed to unsafe nitrate concentrations in their drinking water.

Section 3 summarizes another cost of nitrates in the state—lost recreation benefits. We discuss the impacts of agricultural runoffs (mainly nitrogen and phosphorous) on Iowa’s lakes. We focus on the contribution of these pollutants to the development of harmful algal blooms (HABs), a noxious form of algae that is harmful to human health. We document an increase in the prevalence of beach advisories and closures in the state from HABs. We then value some of the recreational benefits of meeting Iowa’s NRS targets. Improving the quality of Iowa’s lakes by meeting the NRS targets would increase recreational benefits to all Iowans by approximately $30 million per year.

In Section 4, we discuss the current state of knowledge on adverse human health impacts from exposure to high nitrates in water. A substantial epidemiologic and public health literature documents associations between nitrate exposure and blue baby syndrome in infants. Other work suggests that long-term exposure to nitrates, even at low levels, may also be associated with other adverse health impacts. We conclude the section by discussing the need for mo