Low-water crossing that restricts fish passage © Barbara Charry/TNC
Upgraded crossing that mimics natural stream processes and doesn’t restrict flow © U.S. Fish and Wildlife Service
Crossings That Benefit People and Nature
If you’ve driven through the Ozarks, you’ve most likely encountered a low-water crossing. This is where the road dips across a creek bed, allowing vehicles to cross the stream. While there are many different types of low-water crossings, most are not good for nature or for people. “Poorly designed low-water crossings can be a big threat to our aquatic species,” says Drew Holt, The Nature Conservancy’s Western Ozark Waters coordinator in Missouri. “They act as literal roadblocks for fish and other organisms, preventing them from traveling up or downstream to access the food,
The Nature Conservancy in Missouri has been working with partners, including the Missouri Department of Conservation, U.S. Fish and Wildlife Service and local county governments to identify and prioritize low-water crossings to replace or modify based on their social, environmental and economic benefits. Some of the characteristics they are looking to replace are crossings that restrict natural stream flow, particularly during floods; shallow crossings that have water depths too low for many organisms to move through them and that lack streambed material; and perched, or raised crossings that are above the level of the streambed. Crossings should be large enough to allow fish, wildlife, flood waters and debris to pass through, and they should be open bottomed or sunk in the streambed to allow sediment to move along the streambed and water depths that are similar to the surrounding stream. Using nature-based solutions to upgrade low-water crossings that are fish-friendly and mimic natural stream processes not only improves the health of the stream and enhances river- related recreation but also improves safety and mobility for our communities.
“Poorly designed low-water crossings can be a big threat to our aquatic species.” Drew Holt, Western Ozark Waters coordinator
cool water and spawning sites they require.” But these crossings also pose
a potential threat to people. “During heavy rain events and flash floods, low-water crossings become impassable or unsafe to travel on, and communities can become separated from the emergency services they require,” says Holt. According to Missouri’s State Emergency Management Agency, from 2015 through 2019, 40 of Missouri’s 50 flooding deaths—80 percent—were people who had been in vehicles. Less than a foot of moving water is enough to push a vehicle, and two feet of water can cause a car to float.
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Missouri missouri@tnc.org nature.org/missouri
The Nature Conservancy P.O. Box 440400 St. Louis, MO 63144
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