Storm surge overwash in Charlestown barrier-strip island due to nor’easter storm in March 2018. Photo © Jeeban Panthi

Saltwater Intrusion, a “Slow Poison” to East Coast Drinking Water

As the American West faces extreme drought and water shortages, another crisis is emerging on the East Coast: saltwater intrusion.

Southeastern states have been dealing with the threat of saltwater intrusion for decades, but salt is quickly creeping inland on the northern Atlantic Coast, too. In Hilton Head, South Carolina–an island town known for its sprawling golf courses and beaches–saltwater has overtaken half of the drinking water wells. Five more wells are predicted to become unusable in the next two years. 

Fixing the problem is expensive. Hilton Head has already spent $129 million on water infrastructure. City officials expect to spend tens of millions more in the next decade. Other coastal towns like Ocean City, Maryland, are anticipating the same fate. While wealthy resort towns can spend large sums on water treatment, low income and rural communities often have independent wells and limited resources to purchase home water treatment options, rendering them disproportionately affected by this emerging threat.

At low concentrations, salty water is more a nuisance than a health threat. But higher concentrations can cause health problems like hypertension and increase the risk of stroke in elderly people. Despite the risks, governments and researchers seem more concerned than citizens.

Dry: A Weekly Western Drought Digest — August 2, 2022

• As of July 26, over 43 percent of the U.S. and Puerto Rico is in drought, up one percentage point in the last month.
• The U.S. House of Representatives passes a wildfire and drought package to address declining water levels and dry conditions.
• Colorado Parks and Wildlife predicts some of its reservoirs will completely dry up in coming weeks.
• A city in northern Texas expects to run out of water for its residents as drought conditions persist. 

The Watsonville, California, recycled water facility, completed in 2009, purifies wastewater from the city of Watsonville for use by farmers in the Pajaro Valley. Photo © Brett Walton / Circle of Blue
 

Here Comes the Sea: The Struggle to Keep the Ocean out of California’s Coastal Aquifers

Driving on the world-famous Route 1, just south of Watsonville, California, a traveler looking west across fields of strawberries can see the great silvery expanse of the Pacific Ocean.

The land is heavy with a harvest that will soon be trucked to grocery stores and fruit stands throughout the United States. The Pacific, in the late afternoon sun, dazzles like camera flashes. But the ocean also is stealthy. It creeps inland in less obvious, more destructive ways. Beneath the berry patch, a rising tide of salty water threatens one of the most lucrative and productive farm regions in the country. Coastal wells are slowly being poisoned with rising concentrations of chloride.

Saltwater intrusion challenges nearly every town and farm district in California that borders the Pacific. Many have been fighting back the ocean for generations. The first state report to document the salt problem in the Salinas Valley, a farming center just south of Watsonville, was published in 1946. Orange County, a wealthy county near Los Angeles, built a facility in 1976 that injects treated wastewater into the aquifer, to form a freshwater barrier against the ocean.

Kept in abeyance along the Central Coast by prudent investments to establish freshwater barriers made in the last two decades, the salt surge is again pushing forward because of the state’s four-year drought emergency, Circle of Blue reported in 2015. In response, coastal communities redoubled efforts to protect their water supply from the ocean, by recycling wastewater, expanding existing recycling systems, and looking for alternatives to the groundwater supplies that gave rise to a farm industry worth billions.