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Project ID: 2004CO105B

Title: Determination of Ecosystem Response Thresholds to Nutrient of Flowing Waters in Montane Colorado

Project Type: Research

Focus Categories: Water Quality, Nutrients

Keywords: Nutrients, Nutrient criteria, Clean Water Act

Start Date: 03/01/2004

End Date: 02/28/2005

Federal Funds: $8,500

Non-Federal Matching Funds: $17,109

Congressional District: 2nd

Principal Investigator:
William M. Lewis


As required by the USEPA under the Clean Water Act, the state of Colorado must respond through a staged process to the release of federal criteria for nutrients (nitrogen and phosphorus) in surface waters. The state may accept the USEPA's criteria as state standards or it may develop standards independently to achieve the objectives that are the focus of the national criteria. An approach that is tailored to the specific characteristics of Colorado waters and that is firmly based on protection of beneficial uses is preferred by CDPHE regulatory staff and would be most consistent with the history of water-quality regulation in Colorado. The greatest deficiency of information in pursuit of this objective is the absence of a coherent and standardized body of data showing the response of flowing waters, particularly at montane elevations, to increments of concentration in phosphorus and nitrogen. This project proposes a collection of data specifically to fulfill this need. Response variables, which are intended to characterize the status of aquatic ecosystems and thus to be relevant to protection of aquatic life, include biomass and composition of attached algal communities and biomass and composition of invertebrate communities in flowing waters. Samples are to be taken in a standardized manner at 25 carefully selected sites representing three elevational zones. Response variables will be measured at each site; sites will be selected so that all sites are represented by historical monitoring data for the critical nutrients. The objective of the study is to find thresholds of significant response to phosphorus and nitrogen enrichment, and on this basis to move toward the setting of standards that reflect protection of the beneficial uses associated with aquatic life. An expanded scope is also described in the event that additional funds become available.

Progress/Completion Report PDF

U.S. Department of the Interior, U.S. Geological Survey
Maintained by: John Schefter
Last Updated: Tuesday July 12, 2005 2:53 PM
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