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  • Arroyo Chico basins restored in time for the rain

    Jul 07, 2022 | Read More News
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     hydroseeding
    Hydroseeding involves the application of a mix of native vegetation seeds, mulch and
    water to the basin's slope and bottom.
    Just in time for monsoon season, Regional Flood Control District staff and volunteers repaired damage caused by unauthorized trails in the Arroyo Chico Park Avenue detention basins. 


    “A neighborhood resident reported that bicyclists destroyed vegetation and basin slopes next to the Barrio BMX Trails,” said Jennifer Becker, environmental planning manager with the district. “We couldn’t imagine how much damage was being done. Then, at our request, a neighbor walked through the area with a fitness tracking app. He sent us the GPS track that showed all the unauthorized trails.”

    District staff teamed up with Natural Resources, Parks and Recreation (NRPR) employees to tackle the damage.

    “My usual group of restoration volunteers came out and worked with Flood Control staff,” said Neil Stitzer, NRPR trails coordinator. Tucson Audubon Society volunteers also helped out. Over the course of two days in May, about 25 people did the hard manual labor of closing and blocking all the trails. After digging and raking, “We covered the trails with branches. On the eroding slope trails, crews built about 20 media luna. A media luna is a one-rock tall dam in a crescent shape,” explained Stitzer.

    Branch trimmings came from NRPR maintenance work in other County parks. The district provided rock cobbles. The rock dams reduce erosion, slow water coming down the slope, and promote water infiltration to help native plants grow.  

    Stitzer could understand how unauthorized trails developed. “Maybe the kids thought it was another place to ride on the way to the BMX track,” he said about the basin covered with desert shrubs, cholla, and agave. “But authorized access to the track is from Fremont Street.” This way bicyclists avoid riding through a cactus patch, too.

    Staff and volunteers also built about 25 rock piles to further dissuade bicyclists from riding through the area. The rock piles do more than block bike tires.  Stacked into various shapes and heights, rocks and branches provide shelter to a variety of lizards. 

     spiny lizard
    Neighbor Addie Leimroth photographed desert spiny lizards
    hiding in the rock piles only a few days after the restoration.
    Neighbor Addie Leimroth photographed desert spiny lizards hiding in the rock piles only a few days after restoration.


    “The U.S. Army Corps of Engineers and the district built Arroyo Chico Basins to reduce flooding in downtown and on Fourth Avenue,” explained Becker. The Park Avenue portion of the project forms the downstream collection point, adding to the flood prevention benefits of basins located at Randolph Golf Course and Cherry Field, along Kino Parkway. During heavy rains, water from central Tucson flows into Arroyo Chico and these basins temporarily slow the water, allowing the ground to absorb it.

    Maintaining these basins as flood control infrastructure stops monsoon run-off from potentially flooding shops, restaurants, offices, and houses. In fact, the Arroyo Chico project removed over 1,300 residential, multi-family, commercial and industrial structures, as well as three schools, from the 100-year regulatory floodplain.

    In constructing the Park Avenue Basins, the district and NRPR partnered with local bicycle enthusiasts to rebuild the Barrio BMX track. Volunteers maintain the bike track to County specifications.  A paved path circles the basins; other public amenities include two turf areas, benches and public art.  However, basin interiors are regulatory flood control and vegetation mitigation areas that are off-limits for bicyclists.

    The unauthorized bike trails destroyed desert habitat and eroded earthen basin slopes, creating a possibility of water rushing through the area rather than seeping into the ground.  

    After crews covered and blocked the illegal trails, Janice Hughes, district project engineer, quickly arranged for “hydroseeding” where a contractor applied a mix of native vegetation seeds, mulch and water to the basin’s slope and bottom. New plants should grow quickly with the summer rains. Next, the district will install larger native plants and young agave. Eventually the flowering agave will provide food for migratory bats.

    This summer’s restoration efforts bring the detention basin back to its original purpose: collecting water and letting it infiltrate. 

    Becker summed up the joint effort: “The project keeps stormwater out of Tucson’s commercial districts and nearby neighborhoods. This is a prime example of stormwater infrastructure that helps an area flourish through flood reduction, riparian habitat preservation, and multi-use community access.”