Levee 'armoring' along the American River Parkway draws concerns

Flood-control officials face a major challenge in the lower American River Parkway: How do they balance the need to place rocks and armor levees against erosion while protecting environmental and recreational interests?
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Flood-control officials face a major challenge in the lower American River Parkway: How do they balance the need to place rocks and armor levees against erosion while protecting environmental and recreational interests?
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Water & Drought

Levee ‘armoring’ along the American River Parkway draws concerns

By Ryan Sabalow

rsabalow@sacbee.com

March 25, 2016 06:21 PM

Years of rumbling dump trucks and backhoes placing 2.75 million tons of rock “armor” along nearly a dozen miles of riverbank is an unpleasant thought for many who bike, jog, fish, bird-watch, golf, boat and swim along the lower American River Parkway.

But to demonstrate why officials currently are planning for some version of that scenario, Rick Johnson, the executive director of the Sacramento Area Flood Control Agency, points to a striking aerial photo taken after one of the worst deluges ever recorded in this region.

The photo was snapped in February 1986 after an extraordinary Pineapple Express storm filled reservoirs and rivers and pushed Sacramento’s flood infrastructure to its limits. The image shows an area near where the Capital City Freeway crosses the American River; it looks as if several giant bites had been taken out of the massive levee there.

Just on the other side of the levee sits the River Park neighborhood. If the rushing river – which at one point was surging with more than a million gallons per second – had eaten away just a few more feet of the barrier, Sacramento would have been awash in floodwater that would have rivaled what swamped New Orleans during Hurricane Katrina. Tens of thousands of homes could have been flooded.

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But it wasn’t until the American River receded that anyone knew how close the city had come to disaster.

“The scary part is you couldn’t see (the damage to the levee). It was all underwater,” Johnson said. “We didn’t even know that was happening until after the water came down. They should have evacuated, quite frankly.”

Prompted by recent changes in state and federal flood control policy – largely in reaction to Katrina – local officials and the U.S. Army Corps of Engineers are in the initial phases of planning a $375 million project that would add a layer of rocky erosion protection along up to 11 miles of the lower American River.

The levees under consideration stretch along segments of the American River, starting where it meets the Sacramento River near downtown and ending upstream near the Butterfield neighborhood, which is about 4 miles east of the Watt Avenue bridge.

 

The project has presented flood control officials with a major challenge: How do they balance the need to armor the levees against erosion while at the same time protecting – or restoring after construction – the stream-side riparian habitat, as well as the trails and river access that make the lower American River Parkway a local treasure?

Such discussions are underway, and flood control officials encourage those interested in the future of the parkway to attend regular riverbank-protection meetings hosted by the flood control agency.

Crews won’t break ground on the project, which still requires both congressional and local funding, for at least three years. Sacramento voters soon will be asked to approve a ballot measure to help fund the work along with several other local flood control upgrades.

Johnson said everyone involved in the planning – from engineers to local environmentalists – would like to avoid miles of rock stacked along the sides of the American River, similar to what’s been done to areas bordering the Sacramento River. Not only is the armor unsightly, it makes the banks of the river inaccessible.

“That’s what we do not ever want to see again,” Johnson said. “This is an opportunity to avoid that.”

Engineers have improved methods for placing and concealing protective rocks. Even so, some park users and neighbors are worried. While few deny that some level of erosion-control armoring is necessary, some are alarmed that the initial plans outlined in environmental-reviews and planning documents portend years of disruption to park users – and potentially substantial environmental harms.

“This is huge,” wrote environmental attorney Matt Carr in an email to a group of river advocates alerting them to the erosion-control project. “The lower American River will never be the same again.”

The documents call for a combination of large chunks of rock known as rip-rap to be placed in spots along the riverbanks along with “launchable rock trenches.” The trenches would be dug between the bottom of the levee and the river. They then would be filled with large rocks before being covered with dirt and replanted with vegetation.

 

The documents say that the work could lead to the removal of up to 65 acres of riparian forest and a disturbance of 135 acres along the American River Parkway, home to birds and other wildlife. Flood control officials say they will replant the forest along the river and increase the amount of trees in the parkway to offset the construction. Still, it will take several years for the vegetation to fully grow back.

Construction would occur primarily in the warm months when river and trail use is at its highest but the river flows are low. The work and its associated staging areas for heavy equipment and materials will close and reroute bike, equestrian and walking trails. Documents state work may disrupt the use of Paradise Beach, the Campus Commons Golf Course, the Guy West Bridge, and the boat launches at Howe Avenue, Watt Avenue and Gristmill Park.

To minimize these impacts, officials say construction won’t take place along all 11 miles at once. Instead, it will be broken up into up to milelong sections over the course of a decade or more.

Flood control officials also caution the documents’ plans should be considered a rough template for the project. They say that as input is gathered and more study conducted, the actual work along the riverbanks is likely to be substantially less invasive.

Army Corps spokesman Tyler Stalker said the documents present “a worst-case scenario.”

“The hope is to be able to reduce some of the impacts within the project footprint,” he said in an email.

In the early 2000s, crews wrapped up similar erosion-control armoring along nearly 4 miles of the American. The trees and other vegetation they replanted has grown back over the years, hiding much of the rock armor. A 1,200-foot section of launchable rock trench across the river from Sacramento State is practically indistinguishable from the rest of the river’s bank.

“It was buried over, and you can’t even tell there’s anything there,” said Sarah Ross Arrouzet, an Army Corps lead planner.

Crews working for the Army Corps in the coming weeks also should complete the last of 22 miles of topside levee work along the river. Workers used heavy equipment to dig into the top of the levees to insert slurry-filled “cutoff walls” as much as 80 feet below the surface. The walls are designed to prevent water from seeping in and under the levee.

At least one prominent local environmentalist and river advocate says he’s optimistic that the upcoming project will be successful in the long run.

“Our hope is that it is not all rock, and to the extent that rock is used, it is covered with soil and vegetation,” said Ron Stork, a senior policy advocate for Friends of the River who’s been involved in the planning process. “Our additional hope is that we can pin down the actual places that may require work and that that work will be creative, smart, and sensitive to the environment.

“There will be short-term construction losses of vegetation,” Stork said in an email. “I’m getting to be an old guy, but I still believe that short-term losses are better than long-term ones.”

Discussions about the future of the lower American River Parkway comes at a critical time for erosion-control funding.

In the coming weeks, local flood officials plan to send out ballots that ask Sacramento property owners to pay for the costs of not just the American River work, but also several other flood-control upgrades across the region. The flood control agency must comply with Proposition 218, a state law governing special-purpose taxes. This requires landowners to vote in an election by mail.

Additional seepage-control work is planned for levees along the Sacramento River from downtown south to Freeport, and in North Sacramento, along several miles of Arcade Creek and the Natomas East Main Drainage Canal. Some of the levees also need to be raised to contain deeper floodwater. The plan includes doubling the size of the Sacramento Weir, located along the Sacramento River near the Interstate 80 overpass, to divert more floodwater into the Yolo Bypass.

Flood control officials also will perform similar erosion protection along up to 10 miles of levees lining the Sacramento River. Most of that work will be south of the Pioneer Memorial Bridge on Highway 50.

In total, those projects will cost about $1.5 billion. When completed, they will satisfy a 2007 state law that requires all urban areas to achieve 200-year flood protection by 2025.

On average, those living in Sacramento’s most flood-prone areas would see a $42 property tax increase.

Ballots likely will be mailed in early May. The measure requires a majority vote to pass.

Ryan Sabalow: 916-321-1264, @ryansabalow.