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Protecting Fish Through Handheld Flow Monitoring

Founded in 1959, non-profit organization Trout Unlimited, has grown to over 400 chapters, 30 offices and 140,000 members all dedicated to the mission of conserving, protecting and restoring North America's coldwater fisheries and their watersheds. Their membership remains steadfast in their commitment "to ensure that robust populations of native and wild coldwater fish once again thrive within their North American range."


Hach FH950 Flow Meter collecting flow data
in Upper Clark Fork area of Montana for
studies to improve fish passage.

One of their primary activities involves carefully monitoring stream flows around irrigation diversion structures, both upstream and downstream, as well as ditch monitoring. According to Justin Thorson, Trout Unlimited volunteer and Fisheries Technician with AmeriCorps,"We are using flow meters to collect data from streams and ditches to get an idea of the amount of fish entrainment." Fish entrainment is defined as fish being transported along with the flow of water and out of their normal habitat (streams, rivers, lakes or reservoirs) into unnatural or harmful environments. "Typically the more water a ditch diverts the more fish will be entrained," Thorson adds. "The collected flow data is used to determine how we prioritize the work of creating (corrective) diversion structures for fish passage improvement."

To improve their flow monitoring capabilities, Trout Unlimited first began purchasing Hach FH950 Handheld Flow Meters for diversion studies in Missoula, Montana. Thorson reports, "The (FH950) meter worked out really well for us. The best part of using the meter is actually being able to see the amount of flow coming through a cross-section without having to do a ton of math. It’s nice being able to simply plug everything in and go."


The Hach FH950 simplifies and speeds up the data collection process for studies being done by Trout Unlimited.

The greatest benefit the Trout Unlimited team has realized using the FH950 is a dramatic increase in efficiency in completing surveys. Thorson explains that now, with the FH950, each diversion survey only takes 30 minutes to complete. He states, "I can’t imagine having to calculate everything by hand now that we can just enter info into the FH950 and it works so well. It definitely has reduced the amount of time we have to put into surveys. Before the FH950 we could only do three diversion surveys a day and now we can get up to five."

Thorson also commented on several of the FH950's beneficial in-the-field features, including its one-of-a-kind electromagnetic sensor capabilities in algae-laden flows and its portability in rugged environments. He stated, “The meter is really lightweight and a lot more compact for field work.” And upon his return from the field, the flow data is easily downloaded to his computer via the USB port, another significant time-saving feature.

Empowered with good flow data, Trout Unlimited is able to ensure their efforts accomplish the greatest amount of good. And for the fisheries of North America, that makes a tremendous difference.

Learn more about the Hach FH950 Handheld Flow Meter here.

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