Allan McMakin photo
The site of the salt works, a detached section of Fort Clatsop National Memorial, is now surrounded by a residential district in the resort town of Seaside, Oregon.
The party wanted salt for flavoring, and needed it for curing meat. No one mentioned it, but they also would rub it into the insides of elk hides to draw moisture out, in preparation for making much-needed clothing and moccasins. On December 28 the officers detailed three enlisted men—Joseph Field, Bratton and Gibson—to proceed to the Ocean and "at Some Convenient placer form a Camp and Commence makeing Salt with 5 of the largest Kittles." Their temporary camp that would have to be somewhat sheltered from winter winds, near to winter deer and elk range, and as far south of the estuary as it could be without requiring them to climb over or around Tillamook Head. It had to be reasonably close to the ocean where seawater—which ancient proto-scientists had regarded as the "sweat of the earth"—could be processed for salt, and correspondingly close to a plentiful source of firewood.
Why didn't they just set up camp on the Netul River? Well, ocean tides did reach some 30 miles upriver, and more or less affected the salinity of the Netul River (now called the Lewis and Clark River), which was only five miles up the estuary. But the mixture of fresh river water with salt water, introducing between 3 and 5 grams of dissolved salts per litre created a brackish soup ranging between 0.05% to 3% of dissolved salts–not enough for efficient extraction of salt. The crew had to find a place on the coast well away from dilution by the outflow from the Columbia River and "Commence making Salt."
Trail to Salt Camp
Alexander Willard and Peter Weiser were sent along to help carry the Corps' five largest kettles. After five days of exploration they finally decided on a location on the beach about 17 miles below the mouth of the Columbia. There was plenty of firewood and fresh water nearby, and several families of congenial Tillamook Indians were their nearest neighbors.
Back at the fort, the rest of their party was without salt for another nine days while the salt camp crew set up camp and got their salt works into gear. Finally, on January 5 Willard and Weiser returned with a gallon of sea salt, representing a good day's production. Lewis found it "excellent, fine, strong, & white." Clark felt that it was "not So Strong as the rock Salt or that made in Kentucky or the Western parts of the U.States."
For a month and a half the detail kept the fires going day and night, lugged a total of perhaps 1,400 gallons of water from the surf, and boiled it down to 28 gallons of salt. Twelve gallons, packed in two small ironbound kegs, were set aside for the return trip as far as the mouth of the Marias River, where they had cached a reserve supply.