With a heave and a tug, National Parks historian Karnell Hillscan lowered the 300-pound sail on a replica Chinese shrimping junk at the request of two friends who came to the Petaluma River’s turning basin near downtown Saturday for a dose of local history.

“I just want to see it in action,” said Jan Ger, 25, a Sonoma State University student from Petaluma.

Ger and her friend Kristina Ballard, 28, of Rohnert Park joined visitors to the pier to set foot on the junk, named the Grace Quan, as well as the Alma, an actual 1891 schooner that in its day brought Sonoma County hay to San Francisco.

River Heritage Days kicked off this weekend along the Petaluma River with tours of replica and restored vessels of the kind sailing crews used to bring San Francisco wares north and Sonoma County’s agricultural products south. The festival included live music and a barbecue at the David Yearsley River Heritage Center, a historic livery stable on the McNear Peninsula.

Although less of a lifeline than it was a century ago, the river still brings in an estimated $10 million to the local economy through commercial and recreational means. The Petaluma River is actually a 13-mile tidal slough that empties into San Pablo Bay.

The event was the seventh held by the nonprofit Friends of the Petaluma River and the San Francisco Maritime National Historical Park to honor the water-bound heritage of Petaluma. Organizers said it was not held last year because of the government shutdown. The event is a fundraiser for the Heritage Center and for a permanent display of the river’s history.

On Saturday, maritime buff Allison Bart of Petaluma and her husband boarded the 59-foot Alma, the last of some 400 locally built scow schooners.

“I saw the sails as we parked and said, ‘We have got to go see that,’ ” said Bart, who was unaware that a tour of the boat was a surprise her husband had planned for the day.

Down in the captain’s quarters, educator Alex Taylor with the San Francisco Maritime National Parks Association described how the Alma brought oyster shells to Sonoma County chicken farmers who wanted to add calcium to feed, and returned to San Francisco with hay.

“Back at the turn of the century, hay was the gasoline for horses,” Taylor said.

Junks like the Grace Quan were built by immigrants from China’s Guangdong province, said Hillscan, a museum specialist for National Parks with expertise in boat-building. They fished for shrimp in shallow bay waters such as the San Pablo Bay. At the time, dried shrimp was one of California’s main exports.

“The Chinese built the railroads. They built the levees in the delta. I wouldn’t be surprised if they built this turn basin in Petaluma,” Hillscan said.

Today, organizers will take a limited number of people in the Alma on public two-hour sails leaving from the Petaluma Marina at 11 a.m. and 2 p.m. The cost is $20.

You can reach Staff Writer Julie Johnson at 521-5220 or julie.johnson @pressdemocrat.com. On Twitter @jjpressdem.