Why continuous and real time?

"Real-time information is breaking new ground in science and technology and will help lead our agency to new ways of providing water-quality notification systems throughout the U.S."
-Robert M. Hirsch, Associate Director for Water

Continuous real-time information is a vital asset that helps safeguard lives and property and ensures adequate water resources for a healthy economy. Continuous real-time water-quality data are needed for decisions regarding drinking water, water treatment, regulatory programs, recreation, and public safety. Additionally, increased data-collection frequency provides an improved understanding of factors that affect water quality.

Advances related to monitoring technology are enhancing our understanding of water-quality issues. These advancements include, for example, innovation and new water-quality sensors, monitors (multiple sensors in a single probe), data recorders, and transmission equipment. In-stream water-quality sensors provide continuous measurements (typically, every 5-60 minutes) of water-quality conditions that may vary widely over short periods of time, such as before, during, and after storms or during tidal fluctuations. When these data are available in real time, water management officials can be notified of these changes and are able to respond by altering treatment or collecting additional data. Additionally, real-time measurements for temperature, conductance, and turbidity can be statistically related to other important properties, such as indicator bacteria that are more costly and difficult to monitor and analyze. Continued development, testing, and deployment of a new generation of real-time sensors for water quality have the potential to greatly increase the level of information available.

Advantages of continuous and real-time data:

• USGS real-time water-quality data are available to everyone on the Internet.
• The time-density of continuous data improves our knowledge and understanding of relations between water quality and changes in hydrology, geology, and land use.
• Increased data-collection frequency provides an improved understanding of factors that affect water quality.
• Continuous data provide richer data sets for developing tools and models for extending observed water quality to unmeasured streams and enables development of better management tools for ensuring stream quality protection.
• Notification of water resource managers in real time, eliminating delay between sample collection and lab analysis may be critical for warning the public for recreation or for water treatment.
• Real-time data can decrease time and costs associated with manual sampling.
• Continuous data provide better measures of water quality relative to water-quality criteria compared to a few samples collected during a year.
• Continuous data measure water quality changes at night and during storms when samples are seldom collected and when storm events can have major effects on concentrations and loads.