Getting clear on turbidity: Sensors measure cloudiness of CAP water

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CAP Canal

Central Arizona Project (CAP) continues to manage its system for reliability and improve water quality data for CAP water users, even to the grainiest of details – like advanced turbidity sensors.

Recently, CAP completed installation of four permanent turbidity sensors in the canal system. In general, the less turbid the water, the higher the water quality. Turbidity is a measure of how cloudy the water appears, usually due to natural sediment carried along from the river. The sensors are “FTS DTS-12 laser diode” self-cleaning sensors that provide 100 readings every five seconds.

CAP delivers raw Colorado River water to users, and most of the municipal users treat the water before delivering it to their customers.

Turbidity matters because the level and method of water treatment might vary depending on how much turbidity is detected in the water. For tribal and agricultural users, highly turbid water can have negative impacts such as clogging soils, causing sedimentation in pipes and in fields, and increasing the likelihood for algae blooms. Turbid water can even clog recharge projects. Levels of turbidity change by season, as well as through actions such as releases from Alamo Dam by agencies with varying interests in the Colorado River.

One of the additional benefits of these new sensors is that the laser diode, a semiconductor device, doesn’t degrade, and so maintenance and calibration is only required once a year.

Turbidity is just one physiochemical characteristic CAP monitors for water users. See the facts on CAP water quality.

The turbidity data can be viewed on the AquaPortal interactive map application. In addition, users with login credentials can plot canal flow and turbidity on a chart to see how discharge from each of the pumping plants impacts downstream turbidity levels.

By improving the technology that assists water users with their treatment processes, CAP continues to work collaboratively to serve users of their Colorado River water in central and southern Arizona.

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