This project was implemented over the period from November 2007 to December 2008. Using historical survey data and other data for heavy metal pollution of agricultural land in Taoyuan, Hsinchu, Taichung and Changhua, four heavily polluted irrigation channels were selected to be the targets of water quality and agricultural land soil heavy metal sampling and data analysis, in order to investigate the relationship between irrigation water quality and heavy metal pollution of agricultural land soil, and to put forward preventive measures and management strategies to combat the pollution of agricultural land by heavy metals. The data used in the study included data compiled by the Department of Water Quality Protection, Environmental Protection Administration, individual irrigation associations, and the Soil and Groundwater Pollution Remediation Fund. Collation of the data recorded by the irrigation associations’ water quality monitoring sites confirmed the existence of 45 highly polluted irrigation channels, of which 15 were located in Taoyuan, 2 in Hsinchu, 4 in Taichung, and 24 in Changhua. Four of these highly polluted channels were selected for further study. In all, water quality sampling was performed at 121 locations, sediment sampling was performed at 121 locations, and soil sampling was performed at 16 locations. The data analysis results showed that heavy metal pollution of sediment was most severe, with 50 out of 121 sampling sites (41.3% of the total) displaying heavy metal levels above the maximum acceptable level. For agricultural land the figure was 3 out of 16 sites (18.8%), and for water quality it was 16 out of 121 (13.2%). Preliminary analysis suggests that the main reason for this situation may be the excessive disparity between the water quality standards applying to effluent and those applying to irrigation water, resulting in pollution of agricultural land by industrial waste water. The data obtained during the past year have been integrated with a Geographical Information System (GIS). Using water quality monitoring data for the past five years (From 2003 to 2007) compiled by the four irrigation associations in question, it has been possible to identify those sampling sites where follow-up sampling has been performed and where follow-up sampling showed pollution levels that were still above acceptable levels. It is suggested that further surveys should be undertaken with respect to those districts where past soil pollution survey results have shown Level 5 pollution in the case of copper and zinc pollution, and Level 4 pollution in the case of other heavy metals.

Irrigation water quality monitoring, Heavy metals, Early warning system