organisms at higher trophic levels. The dieback of seagrasses and corals and reduced populations of fish and shellfish have been linked to excess levels of nutrients in coastal waters as well.
Unlike solids and many toxic organic compounds, nutrients are highly soluble in water and therefore highly mobile in coastal systems. Compared with concerns associated with nutrients, problems associated with solids and toxics generally occur more locally. Nutrients can be transported much further, and often there is a time lag between the introduction of nutrients into a water body and the adverse effects associated with eutrophication. Thus, problems related to nutrients can occur on a large scale and may be more difficult to discern.
Nutrients enter coastal waters from every potential point and nonpoint source including: wastewater treatment plants, agricultural runoff, urban runoff, groundwater discharge, and atmospheric deposition. The relative contribution of nutrients from each of these sources varies from area to area depending on local and regional hydrology, land-use patterns, levels of wastewater treatment, and other management practices. Concerns about nutrient enrichment should be addressed in the development of wastewater and stormwater management strategies.
No one technology or management control will resolve all wastewater or stormwater management problems. An effective management system must include a suite of technologies and controls tailored to the specific needs of the region. In addition, over the past decade, it has become clear that the best approach to pollution control is pollution prevention wherever possible. It is particularly important that the options not be limited to end-of-pipe treatment strategies.
In the case of wastewater management, municipal systems have found that industrial source control and pretreatment programs can result in significant reductions of metals, toxic organics, and oil and grease (AMSA 1990). Reduction or elimination of these constituents from municipal wastewater treatment plant influent results in better quality sludge, which can then be used for beneficial purposes. It also reduces the discharge of these materials in the effluent to the environment where they may cause harm. Phosphate detergent bans, for example, have resulted in significant reductions of phosphorus from wastewater effluent. It should be noted that an effectively implemented preventive maintenance program in the industrial pretreatment and/or municipal wastewater treatment plants can limit unexpected shutdowns of critical equipment or systems, which could cause bypass of partially treated or untreated waste to receiving waters.
In the case of urban runoff, street sweeping, warnings stenciled on