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image - construction at Folsom Dam

Natomas levee improvements hit high gear

Published April 15, 2020

With the Sacramento River to its west, and the American River to the south, the Natomas Basin sits at the confluence of two major waterways. Streams, creeks and tributaries mark the northern and eastern boundary. Water surrounds the basin’s perimeter.  Levees help keep flowing waters in their channels and out of growing neighborhoods, where approximately 100,000 people live, but a breach to any section of the 42 miles of levee surrounding Natomas could be catastrophic.

This wasn’t always the case. Historically, the Natomas Basin was home to agriculture. For decades, a sea of bean and alfalfa farms sprouted from the soil here. It wasn’t until the early 2000s that Natomas really became the suburban hub we know it to be today, more than doubling its population. 

In 2005, Hurricane Katrina swept through the southeastern United States. Its devastation resulted in more than $161 billion in damage to the region and led communities across the nation to wonder, “Could this happen here?”

While Sacramento doesn’t get Category 5 hurricanes, aging flood risk reduction facilities combined with close calls in 1986 and 1997 and a trend of growing storms have provided flood managements experts with enough information to have a pretty good idea.    

“Sacramento is considered by many to be the most at-risk region in the nation for catastrophic flooding,” said John Hoge, senior project manager for the U.S. Army Corps of Engineers.

“Record storms in 1986 brought Natomas to the brink of flooding,” Hoge explains. “Extensive emergency levee work and flood fight efforts saved Natomas from being flooded.”  

The 1997 storms, while not as large as the 1986 event, showed that Natomas levees were not only susceptive to through-seepage but also provided clear evidence that underseepage was a serious risk as well.

In order to address the seepage issues that affect levee performance, the Corps and its partners, California’s Central Valley Flood Protection Board, California Department of Water Resources and the Sacramento Area Flood Control Agency, evaluated the risks associated with nine segments (referred to as reaches) of levee surrounding the basin.

The study found that even smaller, more common storms could cause significant flooding if levee failure occurred.

In an effort to expedite the project, SAFCA began improving levees surrounding the Natomas Basin in 2007, and by 2012 had completed upgrades to approximately 18 miles of levee, primarily along the western perimeter of the basin. In 2014, the Corps received authorization to move forward with work to complete the remaining 24 miles of levee improvements.

After completing work at the segment referred to as “Reach D” in 2019, the Corps will have active construction in three of the nine levee reaches this year, as the Corps and its partners race to complete this important flood risk reduction work by 2024.

“We know these projects will, at times, bring significant inconvenience but the risk and consequences we face by not completing this work are too severe,” Hoge said.

Here’s where the project currently stands for each of its nine levee reaches, and the remaining “windows” phase:

Reach A (Garden Hwy between Gateway Oaks Dr and San Juan Rd): 
The 65% design was achieved in Summer 2019. The 95% design is scheduled to be completed this summer.  Levee improvement construction is scheduled to start in spring 2022.

Reach B (Garden Hwy between San Juan Rd and Elverta Rd): 
A $59.8 million contract was awarded to Teichert-Odin JV in November 2019. Construction will begin in spring 2020, and is expected to take two construction seasons (April 15 to October 31) to complete.

Reach C (Garden Hwy between Elverta Rd and Howsley Rd): 
This reach was largely completed by SAFCA with the exception of the Pritchard Lake Pumping Plant and Pumping Plant 2, both of which will be completed later in our “Remaining Windows” phase.

Reach D (Howsley Rd between Garden Hwy and Natomas Rd): 
The Corps completed construction of this section in 2019. Work at Pumping Plant 4 required some redesign, which will be completed this fall, and construction will occur in 2021.

Reach E (Natomas Rd between Howsley Rd and Sankey Rd): 
Completed 35% design and expect to be at 65% design in July 2020. Construction contract scheduled to be awarded in 2021 and construction work begin in 2022.

Reach F (Natomas Rd/E Levee Rd between Sankey Rd and Elverta Rd): 
Starting the initial design in 2020. Anticipate construction contract to be awarded in 2022.

Reach G (E Levee Rd between Elverta Rd and Del Paso Rd): 
Starting the initial design in 2020. Anticipate construction contract to be awarded in 2022.

Reach H (Northgate Blvd between Del Paso Rd and Garden Hwy): 
Construction to install a seepage cutoff wall along this section began in 2019, and resumed in March 2020. West El Camino Ave is currently closed east of Northgate Blvd for 45 days, and Del Paso Rd will have a similar extended closure where the levee crosses it. West El Camino Ave and Garden Highway will not be closed at the same time. Construction is expected to be completed by October 2020.

Reach I (Garden Hwy between Northgate Blvd and Gateway Oaks Dr): 
Construction to install a seepage cutoff wall along this section began in 2019. Garden Highway between Northgate Blvd and Natomas Park Drive wrapped up work in March 2020. Additional extended closures of Garden Highway between Natomas Park Dr and Gateway Oaks Dr are scheduled to occur between April and October 2020. The bicycle path will have to be detoured to complete this work. Construction is expected to be completed by October 2020.

Remaining Windows (Various locations): 
Some of the project reaches include infrastructure or utilities that requires additional planning and are more difficult to construct. These sections will be completed in a separate phase of work. Design of these sections is set to begin in 2020. 

Note: At segments under construction, all workers are directed to follow the guidelines set forth by the Centers for Disease Control and Prevention and the State of California to help prevent the spread and exposure of the Coronavirus (COVID-19).