Sustainable management of aquatic ecosystems is a worldwide priority; the integrity of these systems depends, in turn, on the integrity of the watersheds (catchments) in which they are embedded. In this article, we present the concepts, background, and scientific foundations for assessing, both nationally and at finer scales, the relationships between ecosystem services, human health, and socioeconomic values in the context of water quality, water quantity, landscapes, the condition of watersheds, and the connectivity of waters, from headwaters to estuaries and the coastal ocean. These assessments will be a foundation for what we have termed “watershed epidemiology,” through which the connections between ecosystems and human health can be explored over broad spatial and temporal scales. Understanding and communicating these relationships should lead to greater awareness of the roles watersheds play in human well-being, and hence to better management and stewardship of water resources. The U.S. Environmental Protection Agency is developing the research, models, and planning tools to support operational national assessments of watershed sustainability, building upon ongoing assessments of aquatic resources in streams, rivers, lakes, wetlands and estuaries.

Caffeine has been suggested as a chemical indicator for domestic wastewater in freshwater systems, although it is not included in water quality monitoring programs. The Third Fork Creek watershed in Durham, NC, is highly urbanized, with a history of receiving untreated wastewater from leaking and overflowing sanitary sewers. The poor water quality originating in the Third Fork Creek watershed threatens its intended uses and jeopardizes drinking water, aquatic life, and recreational activities provided by Jordan Lake. Organic waste contaminants have been detected in both Third Fork Creek watershed and Jordan Lake; however, the sampling periods were temporary, resulting in a few samples collected during nonstorm periods. It is recommended that (1) the concentration of caffeine and other organic waste contaminants are determined during storm and nonstorm periods and (2) caffeine is monitored regularly with traditional water quality indicators to evaluate the health of Third Fork Creek watershed.

Increasing development of exo-urban environments and the spread of urbanization into forested areas is making humans and forest ecosystems more susceptible to the risks associated with wildfires. Larger and more damaging wildfires are having a negative impact on forest ecosystem services, and smoke from wildfires adversely affects the public health of people living in exo-urban environments. Satellite aerosol measurements are valuable tools that can track the evolution of wildfires and monitor the transport of smoke plumes. Operational users, such as air quality forecasters and fire management officials, can use satellite observations to complement ground-based and aircraft measurements of wildfire activity. To date, wildfire applications of satellite aerosol products, such as aerosol optical depth (AOD), have been limited by the relatively coarse resolution of available AOD data. However, the new Visible Infrared Imaging Radiometer Suite (VIIRS) instrument on the Suomi National Polar-orbiting Partnership (S-NPP) satellite has high-resolution AOD that is ideally suited to monitoring wildfire impacts on the exo-urban scale. Two AOD products are available from VIIRS: the 750-m × 750-m nadir resolution Intermediate Product (IP) and the 6-km × 6-km resolution Environmental Data Record product, which is aggregated from IP measurements. True color (red, green, and blue [RGB]) imagery and a smoke mask at 750-m × 750-m resolution are also available from VIIRS as decision aids for wildfire applications; they serve as counterparts to AOD measurements by providing visible information about areas of smoke in the atmosphere. To meet the needs of operational users, who do not have time to process raw data files and need access to VIIRS products in near-real time (NRT), VIIRS AOD and RGB NRT imagery are available from the Infusing satellite Data into Environmental Applications (IDEA) web site. A key feature of IDEA is an interactive visualization tool that allows users to display tailored combinations of AOD and RGB imagery, as well as overlay the VIIRS smoke mask and fire hotspots at pixel resolution (~750-m × 750-m), and zoom into the county level. Two case studies of recent wildfires in the Western US are presented to show how operational users can access and display VIIRS aerosol products to monitor the transport of smoke plumes and evolution of fires in the exo-urban environment on the regional and county scales. The new National Oceanic and Atmospheric Administration (NOAA) Western Region Fire and Smoke Initiative is also discussed, which will enhance IDEA to allow visualization of VIIRS aerosol products down to the neighborhood scale. The new high-resolution VIIRS aerosol products can be used for NRT monitoring of human exposure to smoke, and they can be used to gauge the spread of fires and, thus, provide advanced warning for evacuations and fire suppression efforts, thereby reducing risks to human populations and forest ecosystems in the exo-urban environment.

The Anacostia River, a tributary of the Potomac River that flows into the Chesapeake Bay, is highly contaminated with raw sewage, heavy metals, oil and grease, trash, pathogens, excessive sediments, and organic chemicals. Despite this contamination, recreation on the river is very popular, including kayaking, canoeing, rowing, and sport fishing. There is currently no information available on the potential health risks faced by recreational users from exposure to the river's pollutants. A total of 197 recreational users of the Anacostia River were surveyed regarding general demographic information and their recreational behavior over the previous year, including frequency and duration of recreation and specific questions related to their water exposure. 84.1% of respondents who engaged in canoeing, kayaking, rowing, rafting, or paddling were exposed to water on their bodies during recreation. Some 27.2% of those exposed to water reported getting water in their mouth while recreating, and 60.7% of that group reported swallowing some of this water. This is the first study to examine the exposure to contaminants faced by the recreational population of the Anacostia River.