Population growth has resulted in drastic increase in demand for agricultural products for consumption and also as raw materials for agro-based industries. Associated with this increased demand is the application of agrochemicals to increase yields. This study assessed the impact of agricultural practices employed by farmers in the Tono catchment in the Upper East Region of Ghana on water quality. The study involved a combination of surveys and laboratory analyses. Structured questionnaires were administered to farmers to determine the various agricultural practices employed towards increasing crop yields as well as their knowledge on the environmental effects of these practices among others. Laboratory analysis was performed to determine the levels of physicochemical parameters of the reservoir water so as to ascertain its pollution level. The study showed that farmers in the catchment used mechanized ploughs to till their lands and applied fertilizer and other agrochemicals to increase yield. These practices potentially can pose serious threats on water quality of the reservoir. Although the levels of all the parameters analyzed were within the WHO guideline values, it is recommended that farmers within the area should be educated on proper application of agrochemicals and farming practices in order to ensure that the quality of the water is maintained. In particular, farming around the intake areas of the dam should be prohibited as this constitutes a major source of sediment into the reservoir.
Key words: Agricultural practices, agrochemical usage, surface water quality.