An implementation plan for using biological indicators to improve assessment of water quality in Thailand

Most national standards for assessment of water quality include physical and chemical indicators relevant to specific pollutants and stressors. However, biological communities reflect not only current conditions of aquatic resources but also change in conditions over time and impacts from multiple stressors. Assessing the health of the aquatic community (that is, bioassessments) has proven to be critical in protecting and maintaining healthy surface waters under the mandates of regulatory frameworks, such as the Clean Water Act in the USA and the Water Framework Directive of the European Union. Whereas, in Thailand water standards, bioassessment is lacking in favor of chemical criteria, only coliform bacteria measurement can be considered a surrogate biological parameter. Our paper argues that incorporating bioassessment will improve water resource condition evaluations and recommends the use of the benthic macroinvertebrate assemblage as a bioassessment framework in Thailand. We discuss the implementation of a bioassessment program that consists of two major components, (a) a scientifically valid technical approach and (b) consideration of technical resources for a cost-effective program. The technical design comprises (1) classification of streams into similar groupings, (2) design of a biological survey, (3) a well-documented sampling protocol, (4) calibration of biological metrics for data analysis, (5) development of criteria for determination of ecological condition, and (6) communication of the results to citizens and policymakers. A cost-effective way to develop a bioassessment program that will improve Thailand’s ability to measure water quality and to make good decisions to attain healthy quality status is to establish partnerships by coordinating efforts and sharing data and technology with adjacent regional environmental offices or provinces. This collaboration would be fostered through a long-term national water resources management strategy and clear definition of goals and desired outcomes that are critical components of the overall National Plan for Ecological Health.