PHOENIX (January 2018) – Introduced in the 1800’s for erosion control, salt cedar (or Tamarisk) is an invasive plant accustomed to harsh environments and blankets river bottoms across the Southwest. It spreads easily and can thrive in wet and dry areas. Originating from the Middle East, Asia and parts of Africa, salt cedar grows significantly denser than native riparian plant species and can make flooding worse along rivers. The Flood Control District (FCD) of Maricopa County is implementing the El Rio State Route (SR) 85 Pilot Project to remove 25 acres of salt cedar trees from the upstream side of SR 85 on the Gila River. Some salt cedar will remain and act as a hydraulic shield to help protect over 2000 newly-planted native trees and shrubs from flows in the river. Partially funded by a Gila Indian River Community gaming grant, the native plants will be introduced over three seasons through pole-planting, tall pots and hydroseeding methods.
“Salt cedar has impacted our desert landscape and increased the size of the floodplain,” said Supervisor Clint Hickman, District 4. “The Flood Control District is working to remove and replace it with native vegetation to help reduce the flooding impact on land owners.”
Tree removal began in December and was completed within 3 weeks. Its debris was used on-site to save in hauling and landfill costs and to create an access barrier that will prevent off-road vehicles from entering. The remaining debris was mulched and spread over the site to help retain moisture for future plants. The revegetation area is divided into three zones. The first zone, the Riparian Treatment Zone, will be planted in January with about 500 cottonwood and willow poles. This is the area with the shallowest groundwater.
Nearly 300 tall pot trees will be planted in the Mesquite Treatment Zone in January and February 2018. This deep-planting technique requires no supplemental irrigation and has relatively high survival rates. The Desert Shrub Zone will be hydroseeded in April using a slurry of seed and mulch. This zone sits on a terrace with deeper groundwater. In the Southwest, native riparian ecosystems provide high-quality wildlife a habitat as well as many other benefits, such as groundwater recharge and improved water quality.
“There’s a lot to be gained through this pilot,” said Bill Wiley, FCD Chief Engineer and General Manager. “The Flood Control District will track costs, evaluate planting techniques and plant survival to help make future salt cedar removal efforts more successful.”
A second planting phase will begin January 2019.
To learn more about the Flood Control District, visit FCD.Maricopa.gov.
The Flood Control District of Maricopa County reduces risk from flooding so that property damage and loss of life is minimized, economic development is supported in a safe and responsible manner and stormwater is recognized as a resource for the long-term benefit of the community and environment.