Measures of turbidity in coastal waters, Coconut Island, Oahu, Hawaii, August 31 - September 2, 2005: workshop proceedings

A three day workshop on turbidity measurements was held at the Hawaii Institute of MarineBiology from August 3 1 to September 2, 2005. The workshop was attended by 30 participantsfrom industry, coastal management agencies, and academic institutions. All groups recognizedcommon issues regarding the definition of turbidity, limitations of consistent calibration, and thelarge variety of instrumentation that nominally measure "turbidity." The major recommendations,in order of importance for the coastal monitoring community are listed below:1. The community of users in coastal ecosystems should tighten instrument designconfigurations to minimize inter-instrument variability, choosing a set of specificationsthat are best suited for coastal waters. The IS0 7027 design standard is not tight enough.Advice on these design criteria should be solicited through the ASTM as well as Federaland State regulatory agencies representing the majority of turbidity sensor end users.Parties interested in making turbidity measurements in coastal waters should developdesign specifications for these water types rather than relying on design standards madefor the analysis of drinking water.2. The coastal observing groups should assemble a community database relating output ofspecific sensors to different environmental parameters, so that the entire community ofusers can benefit from shared information. This would include an unbiased, parallel studyof different turbidity sensors, employing a variety of designs and configuration in thebroadest range of coastal environments.3. Turbidity should be used as a measure of relative change in water quality rather than anabsolute measure of water quality. Thus, this is a recommendation for managers todevelop their own local calibrations. See next recommendation.4. If the end user specifically wants to use a turbidity sensor to measure a specific waterquality parameter such as suspended particle concentration, then direct measurement ofthat water quality parameter is necessary to correlate with 'turbidity1 for a particularenvironment. These correlations, however, will be specific to the environment in whichthey are measured. This works because there are many environments in which watercomposition is relatively stable but varies in magnitude or concentration. (pdf contains 22 pages)