SRP, USGS Strong Partners in Water Science

Flow project uses low-impact tech to help SRP save water

May 28, 2019

The normally still air of the Superstition Mountains buzzes with the sound of a small drone operated by USGS geographer Geoffrey DeBenedetto. Nearby USGS hydrologists Brandon Forbes and Chris Smith walk the stream reach to find an ideal location for a canister containing sensors prepared by USGS hydrologic technician Robert Fritzinger.

What do the drone and steel canisters have in common? They're the latest high-tech and low-impact devices being deployed in Fish Creek by a team of United States Geological Survey (USGS) scientists which may soon help Salt River Project (SRP) save water flowing into the Salt River reservoirs (see map).

Fish Creek can present some tricky challenges for SRP, which operates Mormon Flat Dam. During Arizona's monsoon season and winter storms, Fish Creek can experience high flows which can quickly change the elevation of Canyon Lake. "We sometimes need to quickly release water from Canyon Lake to make room for local inflow" says James Walter, meteorologist for Salt River Project. "Working with the USGS to better understand what the Fish Creek flows look like will help us make better real-time decisions about when to release water or when to hold it back."

The collaboration between USGS, SRP, and the Tonto National Forest involves the placement of small sensors, called "transducers", in the stream bed to measure the height of the water surface at five minute intervals. The transducers are protected by a steel canister which are attached to a boulder in the stream. During installation, the drone takes pictures of the streambed to create a three dimensional profile of the channel, so that water flow in the creek can be calculated using a technique called Continuous Slope-Area Method.

"If we can better understand and predict what the Fish Creek flow will be, we can save water by proactively making space in Canyon Lake by pumping water upstream to Apache Lake," Walter says. "This minimizes the potential and size of downstream releases while adding to our water supply. Our 100-plus year partnership with USGS helps our scientific understanding of the creeks and rivers, so we can make better watershed management decisions."

Interested in the science used to measure flow at Fish Creek?