Salt in the water decreasing, but customers not yet out of the woods

12/09/2020

The level of sodium in Point Reyes Station’s drinking water is trending down, but the North Marin Water District is wary that unprecedented salinity intrusion could continue through the winter if rainfall is sparse. To mitigate the problem, the district is building a new well away from Tomales Bay and exploring how to provide drinking water for customers with health risks. The district tests the water weekly for sodium and chlorine, with the goal of understanding how salty the water is. Chlorine measurements helps indicate the scope of the intrusion, while sodium levels affect the taste and create a health risk for certain diets.  The Nov. 17 test was good news: Samples showed 31.9 milligrams of sodium per liter, below the 50-milligram reporting threshold and far lower than the 400-milligram levels seen in August. But the past two weeks, the test showed 219 and 224 milligrams, reflecting the vagaries of a once-a-week test. “We are trending down lower as we go into the winter season, but we’re still experiencing variabilities in the salinity,” general manager Drew McIntyre said. “If we go into a second dry year, it could be that we experience salinity numbers continuing through the wintertime, but we just don’t know yet. This is a long trending process, and you’re not going to see a change in a matter of weeks. It takes months.” The water is undrinkable for many of the district’s 1,700 customers, and the Palace Market has limited bottled water purchases to two gallons. The high salinity presents a health risk for pregnant women and people on low-sodium diets, leading the Point Reyes Station Village Association to pressure the water district to communicate the risks and provide drinking water alternatives for those who don’t have any. Mr. McIntyre said the district is looking at options to provide low-salinity water to at-risk customers next year, though he couldn’t say what those options might be. In the interest of transparency, he will continue to publish a notice in the Light, even when salinity levels are below 50 milligrams. “The Point Reyes Station Village Association is gratified that when made aware of the local health concerns due to high-salinity water, N.M.W.D. responded and is actively pursuing a solution,” association president Ken Levin said. The water system uses three wells. Two are located on the Coast Guard property, where the aquifer becomes salty when Lagunitas Creek flows are low and tides are high, and one is on the Gallagher Ranch, a mile away from the influence of Tomales Bay. Customers draw from the Gallagher well first, but when demand is high enough, they are served with the salty Coast Guard water. In order to phase out the Coast Guard wells, the district is pursuing a second well on the Gallagher Ranch, with the goal of breaking ground next summer. A permitting consultant is submitting a coastal permit this month at the same time a contractor is finishing the design. “We recognize this is an important issue, and we’re continuing to expedite Gallagher well number two as quickly as possible,” Mr. McIntyre said.