Editor’s note: This is the second story in a series about bluff erosion.
By Patrice Kohl
North of Anchor Point and south of Ninilchik, a grassy bench of land known as Hawk’s Beach once overlooked the surf from below a seaside bluff. It was the perfect place for sea lovers to build houses, or at least that’s what the families who purchased plots on the beach thought. Now a great deal of the bench is gone, and six out of the seven houses built on it remain.
Three of the houses hover precariously on stilts as high as 16 feet above the ground with water surging below them during high tides. Two houses stand surrounded by the destroyed remains of failed seawalls built to protect them.
Just one house remains standing on solid ground ringed by an intact seawall. One of the houses originally built on the beach was removed due to erosion.
The story of Hawk’s Beach teaches an acute lesson about the natural and manmade factors that shape landscapes through shoreline erosion.
Researchers launched a field-based phase of a shoreline erosion study on Hawk’s Beach on Friday, hoping to better understand that lesson and how erosion and sedimentation might shape the Kenai Peninsula’s coast in the future.
Marilyn Morris, a longtime resident of the neighboring Plum Bluff subdivision, escorted the researchers to Hawk’s Beach in a Chevy Suburban at about 11:30 a.m. Friday. The Suburban slowly lumbered forward along the coast toward the beach as its tires sunk deep into the shoreline’s loose gravel. Morris carefully watched for bits of rebar, fencing and other hazardous debris the ocean had ripped from Hawk’s Beach’s seawalls and chucked back onto the coast.
The researchers had arrived later than planned and the window of time in which they could access Hawk’s Beach was closing as the tide swallowed up the shoreline. It was the researcher’s first visit to Hawk’s Beach. When they arrived, they walked beneath the houses towering on stilts, inspected the scattered seawall debris and gawked at the severity of the erosion that had taken place.
Erosion at Hawk’s Beach has occurred startlingly fast. When houses were built on the bench of land in the mid-1990s, the 18.1-foot tide line was as far as 30 feet in front of houses. Now, the 18.1-foot tide line is in some places behind the houses.
Both manmade and natural processes have influenced the movement of sediment along the subdivision’s shoreline. In Cook Inlet, sediments continually move up and down the shoreline, but there is a usually a net transport of sediment in one direction. Along the shoreline that includes Hawk’s Beach, this net transport is from the south to the north. But at Hawk’s Beach, a creek just south of the beach’s subdivision has disrupted this flow of sediment. Over time, Stariski Creek has built up a delta that juts out from the shoreline, blocking sediment flowing northward and preventing it from replenishing Hawk’s Beach.
Without replenishing supplies of sediment from the south, waves have eaten more and more of the beach away, and some of the homeowners at Hawk’s Beach have taken extreme measures to protect their homes. Three of the homeowners built seawalls, one of which was permitted and built as it was allowed to be built, one that was permitted but not built according to that permit, and a third that was built without having been permitted at all. Only the wall that was built to permit specifications remains intact.
The other two seawalls, largely built of debris, such as fencing, root wads, scraps of metal, cement chunks and boulders, have been destroyed by storms over the years. In the meantime, the walls have exacerbated erosion for the neighboring houses, which were subjected to wave energy that was deflected off the walls.
When built well, seawalls are good at holding in the land behind them. But they also reflect waves like a mirror, and when the reflected waves interact with the oncoming waves, they excavate the sediment at the base of the wall, making the water in front of the wall deeper and deeper.
“If you use (a seawall) for a port, this is good because if you’re bringing in ships and barges you don’t want sand to accumulate there,” said Orson Smith, department chair and professor of civil engineering at the University of Alaska Anchorage. “But wave reflection makes them an awkward choice as an erosion control measure.”
When waves hit seawalls, the walls also force the energy of the waves to the sides and result in accelerated erosion to either side of the wall.
Consequently, the seawalls have become a highly contentious issue between some of the Hawk’s Beach residents who built them and those who did not and faced higher rates of erosion.
Experts say that while the seawalls may have redistributed erosion rates along Hawk’s Beach, overall erosion in the area would have still been high even without the seawalls, due to the blockage created by Stariski Creek. But they also say seawalls tend to be problematic.
The sediment along coastal beaches is never static. It’s always moving. But when a seawall is introduced, it creates a hard point on an otherwise dynamic beach, which changes wave energy movement and can result in major problems, said Phil North, an ecologist with the Environmental Protection Agency at the Kenai River Center.
The potential for erosion at Hawk’s Beach does not appear to have been thoughtfully considered before the beach was approved for development as a subdivision.
Aside from the beach’s shoreline erosion risks, several other factors suggested development of Hawk’s Beach as a subdivision was unwise, said Morris, who has owned property in the Plum Bluff subdivision north of Hawk’s Beach for about 20 years.
The subdivision was approved without a road and in spite of a freshwater pond and wetlands on the bench, she said. Consequently, people who built homes in the Hawk’s Beach subdivision also bought plots in Plum Bluff so they could use Plum Bluff’s road to access Hawk’s Beach.
Before houses could be built, the wetlands and pond had to be filled in with gravel.
North said Kenai Peninsula Borough regulations are not strong enough to prevent subdivisions from being built in unwise locations, such as flood plains and unstable coastal areas.
“I’ve talked to past borough assembly members about it, and basically they have said the policy is buyer beware, people should know what they were buying,” he said. “Unfortunately, people don’t have the knowledge to ask the right questions. And they usually rely on their government to make sure those questions are asked.”