Water Quality Monitoring

This paper reports the intake water quality of the water supplies system of Chiang Mai, at 5 sites: Mae Ping River, Mae Rim Stream, Mae Kuang and Angkaew Reservoirs, and Irrigation Canal. This study determined the physical, chemical (included heavy metals) and biological (macroinvertebrate and microorganism) characteristics of the raw water every two months from May 2002 to January 2003. The study covered the three seasons (dry, rainy and cold season). The multivariable analysis and cluster analysis results combined with surface water quality standard to evaluation water quality sources for water supply in Chiang Mai City. The dry season had worst water quality at all sites. This is caused by organic matter and nutrient contamination from anthropogenic sources, from domestic waste and agricultural sources in the upper part and catchment areas around the water intakes. Therefore, the intake pumping stations for water supply in Chiang Mai City, were classified as follows: during rainy and cold season all were class 2 or 3 of water quality; and during the dry season all were class 4 of water quality, based on the surface water quality standard, Thailand.