Pathogenic bacteria of urban playa lakes

Abstract

Control of urban surface water quality has been an important goal for federal and state regulators since the passage of the Clean Water Act (CWA) in 1972. Since then, taxpayers and the private sector have spent more than $541 billion on water pollution control in the USA (Carlin, 1990). The reduction of urban water pollution by "end-of-pipe" controls on industrial and municipal point sources has been the primary mechanism to meet CWA guidelines. Less emphasis has been placed on nonpoint source pollution (NPS), i.e., those pollutants mobilized by storm events and transported by runoff across the land surface (Niedzialkowski and Athayde, 1985). NPS pollution, by its very nature, is much more difficult to identify, measure, and control than point source pollution. Conflicts between some federal agency policies and state water quality goals, insufficient data to define NPS impacts and control effectiveness, and politics of local land-use control are also major barriers to controlling NPS pollution (USGAO, 1990). In a 1984 report to Congress, the US Environmental Protection Agency (USEPA) concluded that NPS was the principle cause of the nation's remaining water quality problems. However, only in recent years have studies begun to tackle the problem of NPS pollution.

NPS pollution results from diffuse land-use activities that diminish the quality of groundwater and surface water (Spooner et al., 1991). Episodic inputs of stormwater runoff deliver a variety of nutrients and allochthonous materials that drive rapid fluctuations in the quality of receiving waters. Studies have shown that a large proportion of metals, organics, toxics, nutrients, and dissolved solids are attributable to NPS pollution and stormwater runoff (Gianessi and Peskin, 1981; Livingston and Cox, 1989). Impervious, man-made surfaces in urban settings increase the amount of runoff from roofs, lawns, parking lots, streets, gutters, city parks and playgrounds. Rainwater flows down the path of least resistance, acquiring a wide array of contaminants en route to the urban impoundment. The urban impoundment's proximity to humans increases the likelihood of contamination, human to water and water to human.