City administrations shore up against erosion
With water in the Great Lakes at or near record levels and rainfall in the Midwest well above normal this winter, it’s not surprising that cities around the region are facing erosion issues on lake shores and riverbanks.
According to the U.S. Army Corps of Engineers, which began tracking lake levels in 1918, a record wet 2019 around the Great Lakes has contributed to the high water levels. Lake Michigan is 5 inches higher than the highest monthly average, which was recorded in 1987.
Contributing to those record levels, January precipitation averaged 1.03 inches above normal, ranking as the 17th wettest January on record (1895-2020) for the region.
High water levels translate to billions of gallons of water.
And that means erosion wherever there are high water levels.
Muskegon, Mich., Director of Public Works Leo Evans said his city began to experience small areas of erosion along the shores of Lake Michigan in the summer of 2018. But as early as the spring and early summer of 2019, it saw the problem become critical.
Instead of lake water simply overtopping roads along the shoreline, he said several sections of beach that were open to public recreational use started to “be reclaimed by the lake.”
Evans said the rate of erosion has escalated rapidly in the last nine to 12 months, “matching the rise in the Lake Michigan-Huron basin over the same timeframe.”
The rise in water levels of both Lake Michigan and the smaller adjoining Muskegon Lake washed out both a street and a lakeshore trail that followed the two shorelines while also damaging water pipes beneath the street.
As of February, Evans said the city is “working on plans to repair the infrastructure that we’ve already had damaged and working to preserve everything else we have that’s at risk.” The bulk of the work has been installing riprap, which is rocky material placed in areas prone to wave action and shoreline erosion. The riprap will slow the erosion.
The city has also temporarily raised the grade of one road in order to keep it open. Additionally, Evans said, “We’ve taken steps to block off several sections of storm sewer that were back feeding into streets exacerbating the flooding.”
While creeks may appear to be far less harmful than a great lake, towns like Atlantic, Iowa, have been fighting their own battles with erosion.
“Bull Creek most of the time looks like a peaceful stream running through town,” said Bryant Rasmussen, Atlantic’s parks and recreation director. “But any significant rainfall and all of a sudden it becomes a raging river.”
That raging river has caused significant amounts of erosion to parkland and private property in the city of about 7,000 residents in southwestern Iowa.
“In some areas, we’ve lost about 5 feet along the creek’s banks in the last year,” he added.
Recent engineering studies suggested building culverts and planting bluegrass as solutions to the erosion issue, but Rasmussen is far more excited about a lower cost, more natural answer.
“Instead of a $4 (million) to $5 million project, we are going to return the area to its native state.”
That native state includes planting native grasses, native plants like cattails and trees that will slow down the velocity of rising waters.
In addition to tackling the erosion, Rasmussen said part of controlling the problem is educating homeowners who have settled along the banks of Bull Creek. “Planting bluegrass and mowing it cannot control the amount of water that comes from the creek.”
Rasmussen is enthusiastic about returning the Bull Creek habitat to the plants that Lewis and Clark would have found when their Corps of Discovery passed through the area in the early 19th century.
He said the native plantings project will cost the city $100,000 to $150,000 and will be easier to maintain than the concrete culvert solution. The plantings will also help to return some of the native wildlife like owls, bluebirds, hawks, foxes and beavers to the creek’s banks.
The half-mile stretch of creek that has been the cause of great concern runs through Atlantic school properties, making the project a learning experience for Atlantic’s youth.
“We expect to put signage there explaining the native plants and their benefits. I even see an opportunity for an outdoor classroom there.”
While lakes and creeks individually can wreak havoc with urban life, combine a lake and a river and the erosion issue multiplies.
South Haven, Mich., about 65 miles down the road from Muskegon, faces double trouble from Lake Michigan and the Black River that flows through the city.
In the last few years, residents of the lakeside city have seen their beaches and bluffs washing away as the lake waters rose. Some have even moved their homes back farther on their properties to hedge against erosion claiming the structure.
Kate Hosler, South Haven’s assistant city manager and harbormaster, said this is not the first year there has been concern about erosion.
“Since many of our public spaces abut the waterfront, the city has looked into long-range planning efforts dealing with erosion.” South Haven engaged Edgewater Resources, a firm that deals with waterfront engineering, in 2018 to assist in developing a master plan for the South Beach Bluff area of the lakefront, south of the area where the Black River flows into Lake Michigan.
The proposed plan will provide accessibility to the bluff at the street level and will implement erosion control measures for the bluff slope.
During a recent presentation to the South Haven City Council, Abonmarche, a Midwestern engineering consulting firm, outlined various measures that could help to mitigate riverbank and lakefront erosion.
Among these are wave absorbers, which are structures cut into existing piers or jetties and filled with large multifaceted blocks of limestone known as armorstone. Hosler said, “(The) irregular shape and large weight of the armorstone absorbs and dispels wave energy that would otherwise be reflected and carried up the channel affecting boat slips, seawalls and other public infrastructure in the inner harbor area.”
With the complex infrastructure of marinas and piers as well as the beaches in South Haven, controlling the waters involves more than just saving recreational areas.
“Public infrastructure, such as the wastewater treatment plant, water filtration plant and Bascule Bridge, are critical components to the city,” Hosler added.
In addition to the public infrastructure, cities like South Haven face concerns about private wells and septic systems that could be washed away.
In Muskegon’s case, the public infrastructure affected by erosion is the water main that supplies not only Muskegon but nearby Fruitport Township and Norton Shores.
The cost of remediating lake and river erosion can take a bite out of a city’s budget. Rich Warner, director of Muskegon County’s emergency management department, said in an interview late last year, “A disaster will wipe out your budget, day one.”
Evans said he estimates the cost of repairing the damage to the street, lakeshore trail and water main will be about $300,000. “It will likely take the better part of six to 12 months to develop plans, obtain permits and identify funding for long-term repairs in those areas.”
He said the city has commissioned an engineering study to identify options and costs for long-term fixes to the most critical areas of erosion. “But those repairs will take time and money to bring to fruition.”
The cost of the South Haven project to manage both lake and river erosion, harbor wave propagation, stormwater and utility infrastructure work and flood control can run as high as $13 million, according to the Abonmarche study.
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