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USE OF PROBABILITY BASED SAMPLING OF WATER QUALITY INDICATORS IN SUPPORTING WATER QUALITY CRITERIA DEVELOPMENT
Citation:
NELSON, W. G. AND C. A. BROWN. USE OF PROBABILITY BASED SAMPLING OF WATER QUALITY INDICATORS IN SUPPORTING WATER QUALITY CRITERIA DEVELOPMENT. Presented at ICES Conference, Environmental Indicators: Utility in Meeting Regulatory Needs, London, UK, November 20 - 23, 2007.
Impact/Purpose:
Conference presentation
Description:
We propose that water quality indicator data collected from large scale, probability based assessments of coastal condition such as the US EPA National Coastal Condition Report III can be used to support water quality criteria development for individual estuarine systems. Such regional scale assessments include water quality indicators such as dissolved inorganic nitrogen (DIN), phosphorus (DIP), chlorophyll a, total suspended solids (TSS) and dissolved oxygen (DO). Values of these indicators are subject to high levels of natural variation over short time scales, raising the question of whether median indicator values will be similar to those generated from intensive, site based water quality indicator sampling. We compare results of sampling for DIN, DIP, chlorophyll a, DO and TSS from three studies. Intensive data collected within Yaquina Bay, Oregon over periods up to 8 years, are compared with data from six additional estuaries collected during 2004-5, and with probability based sampling from 14 Oregon estuaries in 1999-2000. For all indicators except TSS, medians from the probability based survey were relatively similar (within +/- 50%) to that from the intensive sampling. In some cases such as for DO, differences were less than 10%. We conclude that regional water quality indicator sampling may provide data that are of value in supporting development of interim water quality criteria.