LEVEES: ‘We are in pretty good shape’

that wasn’t the case in past events.”

In south Sutter County, Reclamation District 1001 is responsible for maintaining the levees near the confluence of the Feather River and Sacramento River.

“With everything that came at the levees this year, I think they did a good job,” said Joe Henderson, RD 1001’s general manager. “We had some added support from DWR, the U.S. Army Corps of Engineers and MBK Engineers. They all came to help support the confluence area, which was a main area of focus, or problem area.”

Henderson said the high-water levels in the river for an extended period of time – about 60 to 70 days of the river being at monitor stage – caused various issues, but the district and state agencies were able to prevent any major flooding from occurring.

“This event – what my engineers call it – was a duration event. That’s what caused the seepage and boils, because it was just a very long time to have that amount of water on the levees,” Henderson said. “But based on that and the support we received, as well as the high tonnage of rock that was laid down, I think overall we are in pretty good shape.”

The Three Rivers Levee Improvement Authority has done about 29 miles worth of levee work along the Bear River, Feather River and Yuba River – totaling more than $420 million. Some of the work completed by TRLIA includes establishing setback levees and 100-year/200-year flood protection standards for areas in the county like Plumas Lake, Arboga, Olivehurst, Linda and the Goldfields area.

“The levees did terrific,” said Paul Brunner, executive director of TRLIA. “There weren’t any issues along the Feather River in areas that Three Rivers improved or has worked on.”

Brunner, like Inamine, said this year’s string of wet weather was a test for the levee system. However, considering the situation that occurred at Lake Oroville, he said it was relatively normal – in terms of flow levels in the Feather River, he said it equated to about a 10-year storm.

One of TRLIA’s projects in the recent past was on about 6 miles of setback levee along the Feather River. The project essentially widened the floodway by moving the levee about a half-mile back from the river.

“It allows the Feather to spread out, instead of us having to build the levees higher and higher,” Brunner said. “It really helped improve the flow dynamics and reduced underseepage effects quite a bit.”

John Nicoletti, a member of the Marysville Levee Commission, said the Marysville Ring Levee remained in great condition throughout the past several months.

“We just got tested in a lot of different areas, but it gave us a change to better understand high-flow events and where the real threats are,” Nicoletti said. “It was really helpful to have the ability to study those things. Overall, the Marysville levees performed flawlessly.”

While the improved reaches of levees that were part of the Feather River West Levee Project – about 36 miles stretching from Thermalito Afterbay to south Sutter County – passed the test, Inamine said there are still unimproved areas in urgent need of repairs.

“Between the state’s work and our work, we pretty much knew where the critically damaged spots were going to be,” Inamine said.

The Department of Water Resources recently completed a project to address erosion issues on the west bank of the Feather River between the Fifth Street and 10th Street bridges. Stresser said the extreme fluctuation in river levels in the river is what caused the heavy damage.

Stresser said the issue of erosion in the stretch of levee occurred fairly quickly, but DWR promptly addressed the area. Around 20,000 tons of rock were put down along the bank to prevent further erosion.

“Now, that whole stretch of the bend has been refortified for erosion repairs, so we will be in good shape for a while,” Stresser said.

The main area of concern in Sutter County was – and seems to always be – near Laurel Avenue south of Yuba City, Inamine said. During this year’s high-water events, the area proved to have the same problems it has had in the past with seepage.

After the state gave SBFCA the go-ahead to make $5 million in emergency repairs in the area, the agency constructed 2 miles worth of berms, which helped prevent major flooding from occurring.

SBFCA also has plans to build a slurry wall this year to further improve flood protection in the area.

Besides problems at Laurel Avenue, there were some seepage issues closer to downtown Yuba City. The U.S. Army Corps of Engineers constructed slurry walls back in 2001.

At the time, the slurry walls met the crite- ria of a 200-year level of flood protection, but have since become outdated and need to be upgraded. For example, designs for the slurry walls placed in 2001 show a depth of only about 10-15 feet, but modern slurry walls – like the ones SBFCA has established along the Feather River – reach a depth of about 100150 feet.

“The corps wall was done after the 1997 flood, so obviously it was an upgrade to what was originally there, but at the same time, it’s something that isn’t performing to the standards that would make it certifiable for 200year flood protection,” Stresser said.

Inamine said the areas are in urgent need of repairs before next winter. SBFCA – on behalf of Levee District 1 – has applied for the corps to replace the slurry walls by next year.

Inamine said the agency is awaiting a decision to see how the corps plans on handling the repairs. If the corps decides not to fund the work, Inamine said SBFCA will work with the state on a local cost-share agreement to complete the necessary fixes.

“We believe this reach will be completed by next flood season. It’s an urgent issue,” Inamine said.

The main issues experienced in Yuba County, Brunner said, had to do with levee sloughing north of Marysville, which were caused by drastic fluctuations in river levels.

“The high flows saturated the banks of the Feather River, and when they would turn off the spillway, the river would recede fairly quickly,” Brunner said. “Riverbanks would then slough off into the water, causing further issues. I think that was probably the most significant issue we experienced.”

With temperatures starting to rise, Nicoletti said residents should be aware that the events over the past several months have caused a massive change to the rivers, both with the banks and the riverbeds.

“I would strongly suggest, if you thought you knew the Yuba River or the Feather River before, it is completely different now,” Nicoletti said. “Right now is probably the most dangerous time to go swimming because of how turbulent and cold it is.”

All in all, the experts agree: if this year’s string of wet weather and the events that followed the Lake Oroville spillway erosion was a test, the Yuba-Sutter area passed. Still, each district and agency has plans to continue improving levees, in preparation for the next high-water event.