Marina General Manager Janet Folk said the closure was devastating for her business, costing more than 90 percent of expected revenue for the last two weeks.
The marina was allowed to remain open during the shutdown, but since the lake itself was off limits, it was unable to use any of its 23 rental boats, which rent from $25 an hour to more than $500 a day.
None of the 300 full-time boat owners were allowed on the lake either, meaning the marina lost sales of fuel and supplies to those customers.
Lake Sonoma Reopens
"We will not be able to make that up," she said, though fishermen had returned to the lake within hours of the end of the shutdown.
The marina ended contracts with most of its seasonal workers early because of the shutdown and put the five full-timers on half-pay. None of those workers will receive back pay, she said, since they are private employees not government workers.
Other federal recreation facilities in the North Bay reopened on Thursday as well, including the Army Corps' Bay Model Visitor Center in Sausalito.
The Point Reyes National Seashore reopened for normal business Thursday morning, including all trails, parking areas and campgrounds, spokesman John Dell'Osso said.
There are a number of academic and non-profit research projects in the park that resumed and it did not appear that any major experiments were damaged by the shutdown, he said.
Park staff was in the process now of contacting outside businesses that work at the seashore and contractors who work on park facilities. Those operations should resume in a matter of days, he said.
Federal offices were open in Santa Rosa, including the Internal Revenue Service and federal probation facilities, and there was a steady stream of people coming in, many apparently interested in paying their tax bills.