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NUTRIENTS IN WATERSHEDS; DEVELOPING ENHANCED MODELING TOOLS

Contact

http://cfpub.epa.gov/si/si_public_comments.cfm

Impact/Purpose:

Improve the scientific understanding of the processes controlling nutrient distributions in surface waters. Produce a suite of enhanced models for characterizing nutrient distributions in surface waters by incorporating improved process understanding in existing models (e.g., WASP), by developing new models (e.g., WHAM, reactive transport), and improving linkages between model components.

Description:

Nutrient enrichment is one of the most detrimental stressors causing water-resource impairment. Of systems surveyed and reported as impaired, 40% of rivers, 51% of lakes, and 57% of estuaries listed nutrients as a primary cause of impairment (USEPA, 1996). In many cases, these impairments are causing devastating changes: i) high nitrate concentrations have rendered the groundwaters and reservoirs in many regions impotable -- especially in the rural areas of the US heartland where these sources are important domestic-water sources; ii) eutrophic effects in many fresh surface waters are stimulating harmful species -- e.g., the zebra mussel in the Great Lakes and pfiesteria in the Neuse River; and iii) the commercial productivity of our nation's coastal waters is in the midst of protracted decline, e.g. hypoxia and "dead zones" in estuaries of the Gulf of Mexico. Because of these and other effects, unchecked nutrient fluxes in the environment constitute one of the gravest impacts on the quality of life in the US.

As part of the effort to address these impairments, EPA is developing limits for total maximum daily loads (TMDLs) to surface-water bodies. The core of a TMDL usually is a model that describes relationships between water-body condition, stressor sources, and/or alternatives for load reduction (USEPA, 2002). Model quality is one of the major determinants of TMDL quality and the lack of publicly available high-quality TMDL models places a major constraint on the ability of states to produce valid TMDLs (National Research Council, 2001). This research task includes: 1) coordinated field and laboratory process research; and 2) model development and enhancement. The ultimate goal of this task is to develop an improved suite of models for the EPA Office of Water (OW) and Regional Offices that allow for characterizing nutrient distributions in surface waters and identifying watershed nutrient sources. Application of the improved model suite should allow assessment of alternatives for load reduction.

References:

National Research Council (NRC). 2001. Assessing the TMDL Approach to Water Quality Management. Washington, DC: National Academy Press, 109 pp.

USEPA. 1996. National Water Quality Inventory 1996 Report to Congress. Office of Water, U. S. Environmental Protection Agency, Washington, DC. EPA 841-R-97-008.

USEPA. 2002. The Twenty Needs Report: How Research Can Improve the TMDL Program. Office of Water, U. S. Environmental Protection Agency, Washington, DC. EPA 841-B-02-002.

Record Details:

Record Type:PROJECT
Start Date:10/01/2002
Projected Completion Date:09/01/2006
OMB Category:Other
Record ID: 56110