Multi-Benefit Restoration Within the Natomas Basin
By Heyo Tjarks, Project Coordinator and Tad Alexander, Senior Project Manager
Since 2007 River Partners has been working with the Sacramento Area Flood Control Agency (SAFCA) to help protect Sacramento and the Natomas basin against flooding through the restoration and mitigation of native habitats along a newly improved levee. SAFCA is a regional joint powers agency whose mission revolves around increasing flood protection for the well-being of human health and life in the Sacramento region while also preserving and enhancing local riparian and riverine habitat.
In 2007, SAFCA began raising and strengthening 18 of the 42 miles of levees along the east side of the Sacramento River within the Natomas Basin. The 53,000 acre Basin is a critical part of the metropolitan Sacramento regional economy, containing 100,000 residents, hundreds of local businesses, a key transportation hub, including the Sacramento International Airport, and Interstates 80 and 5, two critically important highways on the west coast. As with most large-scale infrastructure projects, mitigation was required in order to offset environmental impacts that could not be avoided during the construction process. Understanding the importance of riparian habitat along the Sacramento River, SAFCA designed multi-benefit, on-site mitigation areas in order to create and enhance large extents of habitat as well as wildlife travel corridors between existing remnant habitat and other wildlife preserves within the basin.
Habitat was designed in order to benefit several threatened and endangered species including Swainson’s hawk, valley elderberry longhorn beetle, and giant garter snake to name a few. To implement its mitigation and restoration goals, SAFCA contracted with River Partners to plant, maintain, and monitor over 410 acres of native perennial grasslands, 150 acres of riparian woodlands, and 80 acres of wetlands.
Native Perennial Grasslands
Not only has SAFCA designed on-site mitigation and habitat improvements, where feasible it has endeavored to incorporate them into the new levee improvements. Along the entire 18 mile stretch of the project, the levee slopes and adjacent areas were designed to be seeded with native perennial grasses in order to provide both an engineering and habitat benefit. These deep rooted native grasses provide multiple values including critical erosion control to protect the levee itself, ancillary foraging habitat for the Swainson’s hawk and a stable ground cover necessitating less long-term use of herbicide to control noxious weeds, while also allowing easy access and visibility for routine levee inspections by the local reclamation district.
Since 2008, River Partners has seeded different native grass mixes within the project area. In order to promote the establishment of the native grasses, we are currently undertaking weed control activities including mowing and herbicide applications in order to contain broadleaf weeds and non-native annual grasses. We also conduct scientific monitoring to determine the effectiveness of our weed control activities and to quantify the rate of establishment of the native grasses.
Riparian woodlands have been designed throughout the project area in order to expand and create nodes of larger habitat as well as wildlife travel corridors between restored areas, remnant habitat, and existing wildlife preserves within the Natomas Basin. To date, River Partners has planted, maintained, and monitored over 18,000 native trees, flowering shrubs and plants near the landside of the levee. The understory in these areas has also been seeded with a native grass mix in order to increase habitat value and help displace and control the spread of exotic weeds.
In addition to planting new woodlands, River Partners is also maintaining mature elderberry and oak transplants. The mature elderberries were within the construction footprint, requiring them to be transplanted in order to help protect the endangered valley longhorn elderberry beetle. Going above and beyond, SAFCA also transplanted approximately 1200 valley oaks that were also in its construction footprint. These trees were relocated and preserved with greater than a 95% success rate to minimize habitat losses for the Swainson’s hawk as well as numerous other raptors and cavity dwelling birds and mammals.
The Natomas Basin contains multiple giant garter snake (GGS) preserves which have been geographically disconnected in the north and southern parts of the Basin. In order to improve connectivity between these areas and create additional habitat, SAFCA designed a GGS canal to connect several of these preserves. So far, River Partners has planted, maintained, and monitored over a mile and a half along the banks of the GGS canal with native wetland plants including tules, rushes, and sedges. Areas adjacent to the canal have also been seeded with native grass mixes in order to create additional basking areas for the giant garter snake.
Beneficial Pollinating Insect Plantings
Because agriculture is the primary land use within the Natomas Basin, SAFCA has also included beneficial pollinator planting plots throughout the project area. Because reductions in domestic native bee populations have been seen throughout the nation, it has become more important than ever for us to establish flowering plants and shrubs which in turn provide critical food resources and habitat for native pollinators. These pollinating insects assist in crop pollination and are a great benefit to the neighboring farms. It is for this reason that SAFCA and River Partners, with support from experts at UC Davis, AECOM and the Xerces Society, have begun to seed several plots with a mix of native wildflowers which are designed to have species blooming throughout the year providing habitat for native pollinators. We are currently in the process of managing a few small trial areas while preparing to plant six additional acres of beneficial pollinator plots throughout the project.
River Partners is also assisting SAFCA to increase sustainable agricultural practices in the region by converting 50 acres of conventional agricultural land into organic production. We are currently employing mechanical weed management (i.e. mowing and discing) activities to reduce the weed seed bed in the soil. This land will be maintained as chemical free for three years in order to provide organic farming opportunities.
Multiple Benefits Projects
SAFCA has shown how flood safety and ecological stewardship can go hand-in-hand in the creation of a multi-benefit project. River Partners’ successful implementation of such projects is based on its background in science and agriculture. Our background in science allows us to perform project planning, management, and mitigation monitoring, while our agricultural expertise enables the use of modern farming techniques to ensure quality and cost effective planting and overall habitat restoration.
The above article originally appeared in the June 2013 issue of the River Partners Journal.