ARCATA – Environmental planner Aldaron Laird presented his “Shoreline Inventory, Mapping, and Sea Level Rise Assessment Project” Wednesday, May 30 at the Arcata Marsh Interpretive Center.
Laird walked the entire, 102-mile shoreline of Humboldt Bay to assess the type and status of shoreline features, including both natural and artificial structures. Some 75 percent of the bay shoreline consists of artificial structures, the majority of which are dikes. These structures were built to allow people to fill in salt marsh and create pasture for crops and farm animals.
More than 90 percent of the bay’s salt marsh area has been diked and transformed since the 1800s. Many dikes are failing and there is no comprehensive dike upkeep program in existence at the present time. There are 29 miles of dikes around Humboldt Bay that are in need of fortification.
Laird stressed the need for an umbrella organization that can secure grant funds to repair and maintain the failing dikes. The present situation requires that individual landowners fix and maintain their dikes.
This situation is not effective because when one landowner fails to fix their section of dike, it has an adverse effect on large stretches of land. These dikes are the only protection that low lying residents have against flooding and sea level rise.
Laird sees three main problems:
• Most dikes are over 100 years old and they are failing to stop the flow of water, especially during King Tide events (a concurrence of winter solstice, and the highest tides of the year).
• The sea level is rising and we are not well protected. In the past 100 years it has risen eight inches, and by 2050, sea level rise will reach 16 inches. It’s estimated to rise to 55 inches by the year 2100.
• A Cascadia subduction event could create even more severe flooding problems.
The main thrust of the presentation was that we should invest in shoreline fortifications because, as Laird put it, “we are all in this together” on Humboldt Bay.