Southcentral Alaska stakeholders seek solutions for imminent threats from waterfront erosion

HOMER — For most communities with waterfront, erosion is not a future problem. It's a daily issue for planners, businesses and residents with approaches differing by community.

In Homer, the Alaska Department of Transportation and Public Facilities has used riprap barriers on the seaward side of the Homer Spit near town to prevent the road from washing out.

However, the riprap doesn't go all the way down, and recent high tides and strong winds have eaten away at the coast beneath a number of buildings, threatening to tip them into the water.

The riprap is an engineered solution to a natural problem, or what coastal management experts call "grey infrastructure." To save expense, look toward sustainability and preserve communities, the National Oceanic and Atmospheric Administration is conducting training on the effectiveness of green infrastructure.

It can also be called natural infrastructure, based on what a community is comfortable with, said Lauren Long with NOAA's Office of Coastal Management.

"Natural, nature-based solutions … it doesn't really matter which term to use, just use the terms that resonate most with your stakeholders," she told a group of residents, nonprofit workers and municipal, state and federal agency workers at a workshop in Homer on Sept. 11.

The office recently hosted a round of workshops on using green infrastructure to reduce coastal erosion in Alaska, with stops in Homer, Soldotna and Anchorage. Beyond the basic instruction, the course brought together local planners and experts to talk about ongoing projects.

As a broad definition, green infrastructure includes structures based on natural systems like wetlands and forestry to provide services such as flood control and heat abatement.

They can include a wide variety of project sizes, from landscape level to individual sites, and don't necessarily entirely exclude grey infrastructure, Long said.

"Both approaches are about bringing the natural and built environments together," she said. "…Green infrastructure isn't going to be the end-all-be-all. It's going to be a combination of green and grey."

Many parts of Alaska are less built up along the coasts than on the East Coast, where millions of people live in areas potentially subject to ocean storm surge submersion.

Attention to coastal infrastructure mounted in the aftermath of Hurricane Sandy, which struck the entire eastern seaboard in 2012, leaving behind $70 billion in damage and leading to the deaths of an estimated 233 people.

However, a study published in August 2017 on the damaged communities and their infrastructure later showed that areas with intact coastal wetlands were spared about $625 million in damage because the marshes helped with flood control.

John Rozum with the NOAA Office of Coastal Management, who conducted the workshop in Homer with Long, cited the flood mitigation wetlands as example of an ecosystem service. They're specific to certain areas, and what may work in Massachusetts may not work in Anchorage.

"You have to be able to look at these practices … (and say) if this area was undeveloped, what would happen?" Rozum said.

He pointed to cities that have installed areas of permeable pavement, which allows water to seep through and be absorbed by the ground beneath rather than concentrate into runoff and cause flooding issues, or the addition of trees on buildings or streets to help offset city heat island effects.

Alaska's communities already have more natural areas along their coasts than many areas of the country, he said, and preserving some of those structures — like dunes and coastal wetlands — will help buffer communities from damage and erosion.

Some communities in the state have tackled green infrastructure practices already, impacting erosion in areas inland as well as on the coasts. The Alaska Department of Fish and Game guides landowners who want to restore riverbanks toward practices using rootwad, spruce saplings and other natural vegetation as opposed to seawalls or riprap, in part to protect fish habitat.

The Alaska Department of Environmental Conservation awards grants for projects designed to clean up bodies of water, and some of the funded projects have included green infrastructure projects, said Jeanne Swartz, a water quality specialist with DEC in Anchorage, at the workshop in Homer.

With largely clean waterways, much of the water pollution in Alaska is called non-point-source, such as road runoff.

At the same time, some areas may erode whether land owners and managers try to mitigate it or not. On the Arctic coast and in Western Alaska, some Alaska Native villages are looking at relocating entire communities because their coasts and rivers have eroded enough to leave buildings tumbling into the water.

On the Kenai Peninsula, retreating bluffs in Homer and Kenai have left cities with the puzzle of how to react, with residents and millions of dollars of property value getting closer and closer to the cliff edge every year.

Rozum said in response to a question that bluffs are a type of landscape that's hard to use green infrastructure to help.

"That's the hard part of living on the shore — (bluffs) were designed to erode," he said.

The Matanuska River is another creeping landscape that has left some neighbors with few options other than to simply move. The Matanuska-Susitna Borough has obtained federal funding to buy out some Matanuska River property owners who opt in to the program, with the recognition that the geography of the braided river system makes it likely to move.

The borough began asking property owners about a buyout and applying for federal funds in 2014, officially receiving notice of the funds in March 2018. About 75 percent of it will come from the federal government and 25 percent from the state.

The borough started with 15 properties, but one house became ineligible when it fell into the river in 2017, said Mat-Su Borough Floodplain Administrator Taunnie Boothby. The funds are scheduled to expire in September 2019, giving the borough about a year to reach agreements.

"This is a 100 percent voluntary project," she said. "There is no condemnation (for properties) or eminent domain."

The borough is not actively approaching landowners about the future danger to properties along the Matanuska River, but Boothby said she discusses possibilities with landowners on a case-by-case basis and is watching the success of several river bank revetment projects elsewhere in the borough.

There aren't any such projects on the Matanuska River at present, but landowners could undertake demonstration projects in the future and Fish and Game is actively recruiting for riverbank revetment grantees in the Mat-Su Valley, she said.

Some people ask why the borough isn't looking at solving the erosion problem on the river, but that's beyond the borough's power in both expense and authority, she said. The borough does have two flood service areas in which residents tax themselves for flood service and protection.

"The challenge with that is what they're taxing themselves is not sufficient for maintenance of the dikes," Boothby said. "We have a whole Matanuska River management plan that outlines what activities are acceptable and reasonable … but (fixing the river erosion problem) is not necessarily something the borough wants to tackle."

Elizabeth Earl can be reached at elizabethearl@gmail.com.