Raising Mussels with Smart Irrigation

In southern Georgia, consistent irrigation withdrawal from the Flint River Basin has left native freshwater mussels in critical condition. With an estimated net agricultural worth of over $2 billion annually, the basin has become a technology-testing center for best management practices regarding crop irrigation. However, as a National Geographic special report by Sandra Postel points out, the quickly decreasing water levels resulting from a combination of increased irrigation usage and prolonged periods of drought are forcing the Basin’s mussel population toward an uncertain future.

Mussels, like many mollusks, are a foundational building block of a healthy ecosystem. The mussels that call the Flint River home – such as Oval Pigtoe, Little Spectaclecase, and Shiny-rayed Pocketbook – help keep rivers clean and healthy. Each mussel is capable of filtering tens of gallons of water per day, removing harmful pollutants from the water.

Yet, this vital population is declining, largely due to a form of irrigation dating back to the 1970s called the center-pivot sprinkler. With one sprinkler capable of irrigating up to 200 acres, this irrigation system has turned the Flint River Basin into one of the most prosperous agricultural regions in the southeast. [1]

There are nearly 9,000 center-pivots in operation in the lower Flint basin, irrigating up to 1.8 million acres of land. As more irrigation systems come into operation, stream levels are drastically declining. A recent survey found that the majority of tributaries connected to the aquifer were down by 30-40 percent. [1]

Increased groundwater withdrawals and declining stream flows have left many native mussel species vulnerable to extinction. This year, the U.S. Fish and Wildlife Service has listed seven species of mussels in the Flint River Basin as threatened or endangered.

In 2000, researchers from the University of Georgia and the Flint River Partnership began a mission to improve the efficiency of irrigation in the Flint River Basin. As of today, many farmers throughout the region have equipped their center-pivots with drop hoses that allow for low-pressure sprays that boost efficiency rates from 60 percent to over 80. Perhaps the biggest innovation yet is the ability for farmers to create quadrants and target specific areas of a field with a calculated irrigation volume. The variable rate irrigation (VRI) allows for tailored irrigation with virtually zero loss. Equipped with a GIS sensor, this technology can reduce water consumption between 15 and 30%, and in some cases, actually boost crop production. [1]

Although the system has proven water-saving potential, modern and more efficient irrigation techniques have yet to take hold on mainstream agricultural practices. In an interview with National Geographic, Calvin Perry, a lead researcher at the Stripling Irrigation Research Park commented on the functionality and popularity of the systems. “Despite our many years of effort, its still seen as an add-on. The technology is ahead of the support capacity. It’s all about helping farmers make better decisions.” [1]

The question remains whether smart irrigation techniques can restore stream flows and help boost mussel populations. Different technologies and strategies, such as drop hoses and VRI, are available for farmers to utilize the most efficient means of irrigation. It’s clear that restoring the Flint River Basin will not be an easy task, but the people who most utilize the resource must decide if they are willing to save the biodiversity of their local watershed.

Published September 29, 2016

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