The water in Point Reyes Station is cloudy, thick and salty. For many, it’s undrinkable, and for some, it’s harmful.

An unprecedented intrusion of salt into the water system is stressing the region’s water supply, as residents scramble for water bottles or fill up jugs elsewhere, while the North Marin Water District bores another well away from the influence of Tomales Bay. 

For decades, salt has infiltrated the wells in Point Reyes Station during late summer, but this year the intrusion is higher than ever due to a confluence of factors. Sea-level rise brings bay water closer to freshwater aquifers, and a National Park Service project to remove a series of dikes and dams by Lagunitas Creek in 2008 stripped the watershed of protection from high tides. Two bulk users, a construction company and firefighters, consumed more water this year. The increased demand comes with decreased supply, with less than two feet of rainfall this winter leading the district to declare a water shortage emergency. 

Sodium levels in the well water peaked at 414 milligrams per liter this year, an increase of more than 300 percent from 2017.

“An area that is vulnerable to salinity intrusion has been pushed over the edge,” said Pablo Ramudo, the water quality supervisor for the district.

At the Palace Market, the shelves were emptied of bottled water for two weeks in August, so the grocery store imposed a two-gallon limit to be able to meet demand. Peggy Day, a resident of Walnut Place, fills and hauls jugs from her daughter’s private well in Inverness Park. Ms. Day

has a kidney issue that requires her to drink plenty of water to stay healthy; recently, she began feeling nauseous after drinking her tap water, and it became tough to gulp down. She added more and more lemon juice, but she still couldn’t drink enough. 

A barista at Brickmaiden Breads, Miguel Kuntz, also could not stomach the water, so he’s been filling a six-gallon jug in Inverness every few days. At work, a technician came in to test the water for dissolved solids after the espresso machine was extracting unevenly. As the technician told the staff a story about the hardest water he had ever encountered, his titration device quickly showed Brickmaiden’s water surpassing that level. It was the hardest water the technician had seen in years of testing espresso machines. The bakery has since purchased a reverse osmosis filter, the only kind of filter that strips water of salt.

Around 1,700 residents are affected by the salty water, which is extracted from an aquifer accessed by two wells at the former Coast Guard site. The well water becomes especially salty in late summer, when creek flows are low and after ocean tides are high. 

Following seven years of steady levels of sodium fluctuating between 30 and 50 milligrams per liter at the two wells, the salinity intrusion worsened in 2017, when the level peaked at 93 milligrams per liter. Sodium content continued to rise the next two years, to 140 and 174, then skyrocketed this year, peaking at 414 milligrams per liter.

To mitigate impacts from the intrusion, North Marin mixes the water it pulls at the Coast Guard site with water from a third well, on the Gallagher Ranch a few miles down Point Reyes-Petaluma Road and 15 feet above sea level. The freshwater well, which was connected to the system in 2014, provides clean water but only enough to meet about 40 percent of Point Reyes Station’s demand. The less water the town uses, the more that comes from the Gallagher well, and the less salty the tap water is.

Not everyone tastes the salt, but for some, it’s a health risk. At its saltiest, drinking two liters of the tap water would mean consuming over 400 milligrams of sodium. The recommended daily intake is 2,300 milligrams a day, but for low-sodium diets, the recommendation can be below 1,000 milligrams. People with high blood pressure, kidney disease or heart disease are often prescribed these diets.

Residents are not the only ones buying water from the North Marin Water District. Ghilotti Construction, the company rebuilding Sir Francis Drake Boulevard in the Point Reyes National Seashore, purchased about 3 percent of the town’s water supply from July 2 to Sept. 14, using it to compact the soil on the roadbed.

The water district ended the sale last month after residents observed water trucks pulling from a hydrant at the fire station and questioned why. Although the district’s policies allow it to sell water to a construction company during a water shortage, unless it is for dust control, the district recognized it had made a mistake.

“It’s a gray area, but given the sensitivity of our water system, I had them remove [the meter],” general manager Drew McIntyre said.

Fire engines have also been using well water to fight the Woodward Fire, although how much is unknown. While the construction company used one metered hydrant, firefighters took from multiple hydrants, free of charge.

Other water users include Pardini Water Trucks, which delivers potable water to remote properties and businesses across West Marin, and ranchers in the service area whose own wells need to be supplemented.  

North Marin knows the saltwater intruding on its drinking water comes from Tomales Bay, but where exactly it enters the freshwater system is unknown, as the area’s hydrology and geology are complex. When Lagunitas Creek flows higher in the winter, the intrusion subsides.

The creek also has less protection from tidal influence than it used to. In 2008, the National Park Service converted a 550-acre dairy pasture back into a marsh, now known as the Giacomini Wetlands. The property, formerly owned by Waldo Giacomini, had been diked since 1946, and the creek was dammed each summer to accommodate agricultural operations.

When the park service bought the property in 2000, it found the ranch was polluting the water, degrading wildlife habitat and taking away wetlands, an ecosystem in decline. It proposed removing the culverts, dikes and dams to reconnect Lagunitas Creek and its tributaries with their flood plain.

At the time, the water district worried that saltwater would back up to its wells at the Coast Guard station more often. The park studied the issue in an environmental impact statement but reached no firm conclusions. 

“While there has been a considerable amount of study into the salinity intrusion problem, the exact cause or mechanism by which salinities become elevated is still not totally understood,” the report states. The park service pledged that it would continue to work with the water district to characterize the factors affecting salinity intrusion in the aquifer.

The wetlands restoration went forward with success, but not before the water district strongly urged the park service to fund a pipeline from the well on the Gallagher Ranch to the treatment plant. The park service did not fulfill the request, and the project sat shovel-ready for years until a state grant paid for construction in 2014.

“[The park service] never followed through,” Mr. McIntyre said. “I don’t think they were convinced that we were going to continue to have a salinity problem from their project.”

Now, the district is looking to build a second well on the Gallagher Ranch, so even less water is needed from the Coast Guard wells. The district board raised rates in 2016 to help pay for its construction, and after boring three test wells that didn’t pump enough water, crews found a productive location on the pasture. 

North Marin hired a permitting consultant on Tuesday and is moving forward with design and easement acquisitions. After the California Department of Fish and Wildlife, State Water Resources Control Board and the California Coastal Commission approve the project, construction should take about two months.

Mr. McIntyre said the goal is to complete the well by mid-summer. “It is imperative we move posthaste,” he said.