Reliable time series data can be used to assess the health of aquatic ecosystems provide early warning and detection evaluate the performance of pollution abatement programs. Without adequate monitoring data and knowledge of both watersheds and watercourses, scientists and managers can only speculate about water quality problems, probable causes, likely consequences, and the adequacy of management measures to protect and restore water quality. Groundwater sampling Monitoring is often uniquely tailored to specific issues, the area of surveillance, and financial and time constraints. Reconnaissance monitoring usually involves the periodic sampling of waters over a large area and a long time, and the analysis of a wide variety of water quality parameters. It is valuable for identifying detrimental changes from natural conditions over time.
Objective monitoring responds to a known problem and usually targets specific chemicals.
Such sampling covers a small area and is limited to a shorter period. Most federal and provincial agencies have cut back on programs for routine reconnaissance monitoring in recent years. Today, monitoring programs are usually targeted at specific problems in particular locations in response to public concerns about real or perceived problems. Federal and provincial governments currently sponsor regional and local monitoring. Some municipalities monitor surface water and wells, usually through local health departments.