Jump to main content.

Integrating Probabilistic and Fixed-Site Monitoring For Robust Stream Water-Quality Assessments

Keith W. Robinson 1 and Henry A. Walker 2

1 U.S. Geological Survey, 361 Commerce Way, Pembroke, NH 03275
2 U.S. Environmental Protection Agency, 27 Tarzwell Drive, Narragansett, R.I. 02882.

Determining the extent of water-quality degradation, controlling nonpoint sources, and defining allowable amounts of contaminants are important water-quality issues defined in the Clean Water Act that require new monitoring data. Probabilistic, randomized stream water-quality monitoring is used by the U.S. Environmental Protection Agency to provide statistically valid assessments of water-quality and designated-use attainment for spatially diverse regions. Other agencies, such as the U.S. Geological Survey often uses traditional fixed-site monitoring to assess the temporal variability in water quality among drainage basins representing different land uses or ecoregions. Disadvantages of probabilistic monitoring include the lack of information on sources of water-quality degradation, temporal variability, and the effect of upstream drainages on downstream receiving waters. On the other hand, fixed-site monitoring generally lacks the ability to characterize unmonitored waters, especially when drainage-basin conditions vary. We propose a network design that integrates both probabilistic and fixed-site monitoring activities for more varied water-quality assessments. Using the New England region as an example, an integrated regional monitoring program is proposed that would allow for provide spatial and temporal water-quality assessments necessary for Clean Water Act 305(b) reporting. Such a program would be also useful in determining the effect of different sources of contaminants on receiving streams necessary for 303(d) listings. Results from an integrated monitoring program could be linked to predictive models, such as the New England-wide water-quality SPARROW model, to provide enhanced statistically based predictions of water quality and contaminant sources in unmonitored waters. Present monitoring programs by State and Federal agencies could be efficiently integrated into such a regional monitoring network.

Keywords: Water-Quality Monitoring, Clean Water Act Reporting, Probabilistic Designs, Fixed Site Monitoring, Integrated Regional Monitoring Network

EMAP Home | About EMAP | Components | Data | Documents | Bibliography | News | Site Map

Local Navigation

Jump to main content.