The Vermont Paddlers Club

They did one last year for the first time in many years, and they're doing another one. Here is what the park's website says at this point:

It is anticipated that two releases will happen in 2018. It is likely the spring release will be May 5 & 6, 2018. We expect to have the campground open for the event, and we are taking reservations by directly contacting our Reservation Call Center only (no online reservations). Reservations may be made for a 2-night minimum. If you plan to paddle all day Sunday, you either need to vacate your campsite by 11 AM or book your site through Sunday night.

The Fall release date has been set for September 22 and 23, 2018. Campsites are prioritized for paddlers and a 3 night minimum stay is required, and a maximum of two campsites may be reserved per customer. There is a maximum occupancy of 8 people per campsite, and two vehicles per campsite. Resale of campsites is not allowed. Campsite reservation holders will need to provide the park management a list of site occupants prior to the fall event. Campsites may be booked by calling our Reservation Call Center directly (no online reservations) 11 months in advance. In the fall, Vendors will be on hand selling food and gear. A Concession or Commercial License Agreement is required to serve/sell food, sell gear, and operate tours. The truck shuttle will run 8:30AM – 3:30 PM on Saturday and 9:00 AM – 3:00 PM Sunday. Fees for the shuttle will be set in the summer of 2018. Shuttle tickets are sold on site; cash only accepted. You must provide proof of paid day or camping entry in order to buy a shuttle pass. Times and length of the releases and shuttle may vary due to water conditions and need.