Nutrient Criteria Project

Contact Information

Rich Miller
richm@pdx.edu
Portland State University
Center for Lakes and Reservoirs
PO Box 751
Portland OR 97207-0751
Ph:503-725-9076
Fax: 503-725-3834

Introduction

Overenrichment of surface waters in the United States has been a long-standing problem to the extent that approximately half of the waters reported by the States to be impaired are attributed to excess nutrients and related biological growth. The EPA has established the National Nutrient Criteria Program to address this water quality problem. The surface waters of concern are lakes and reservoirs, streams and rivers, and estuaries and coastal marine waters, and wetlands. Criteria representing enrichment conditions of surface waters that are minimally impacted by human developmental activities will be developed for each of the regions of the country. These will then become the basis for States and Tribes of the United States to develop nutrient criteria to protect the designated uses of those waters.

Nitrogen and phosphorus are the primary causes of overenrichment and are obfious nutrient criteria variables, but biological response variables are also important in addressing the consequences of overenrichment

Limnologists and lake managers have developed a general consensus about freshwater lake responses to nutrient additions, that essentially an ambient total phosphorus (TP) concentration of greater than about 0.01 mg/L and or a total niroen (TN) of about 0.15 mg/L is likely to predict blue-green algal bloom problems during the growing season. Similarly, chronic overenrichment leads to lake quality degradation manifested in low dissolved oxygen, fish kills, algal blooms, expanded macropytes, likely increased sediment accumulation rates, and species shifts of both flora and fauna.

Nutrient criteria development consists of five elements:

1. Historical data and other information to provide an overall perspective on the status of the resource.
2. Present reference sites and their collective reference condition describing the current status.
3. Modeling to refine data implications and analysis above if necessary
4. Objective assessment of all the above information by the States and by the EPA Regional Technical Assistance Groups (RTAG's), a board of State and Federal specialista established in each EPA Region to help develop and administer the National Nutrient Criteria Program, to establish ecoregional criteria, and to review proposed State or Tribal nutrient criteria.
5. Attention to downstream consequences before the criterion is fully established

Portland State University is on the RTAG for nutrient criteria development in the Pacific NW. Data were collected on 12 Oregon and 12 Washington coastal lakes in 2000 and 2001. The data are being analyzed to determine patterns in nutrient levels within the region. In 2002 data collection will concentrate on reservoirs in central and eastern Oregon and Washington and western Idaho.

Resources

EPA Nutrient Criteria Technical Guidance Manual (index of PDF documents).