Crossover relocation preserves beach, protects the town, and enhances beach access
It’s not often that a single solution solves multiple problems and seems to satisfy everyone.
But the recent relocation of Duxbury Beach Crossover #3 by just four-tenths of a mile north of its current location (at the narrowest part of the beach) seems to be just such a solution.
The modest relocation this spring will have an oversized impact. It will:
Stop the significant erosion and deep gully threatening to breach the beach at its most vulnerable location
Protect the town from high-energy waves that could sweep over a breached beach by preserving the barrier beach
Preserve overland access for the the 249+ residential structures of the Gurnet/Saquish community
Reduce the length of a closure of Crossover 3 due to the historical limited nearby bird activity as the crossover is moving to a location with little activity over the last five years.
The old Crossover 3 was south of High Pines at the narrowest portion of the barrier beach, roughly 2.3 miles south of Powder Point Bridge. That access point had been experiencing periodic over-washes since 2006 that slowly created a 30-foot gully on the bayside of the roadway, undermining the integrity of the beach.
However, since winter storm Riley in March of 2018, this area of the beach has experienced significant overwashes every year, which have caused scouring of the dunes adjacent to Crossover 3, and led to the creation of the gully. Each subsequent storm further extended the gully and threatened to undermine the bayside beach.
Earlier attempts to stabilize the area (installing sturdy drift fencing) slowed erosion, but did not solve the problem of overwash. Thus the chances of a temporary breach became more pronounced.
Having an accessway at the narrowest section of the barrier beach system poses significant risk for increased overwash and erosion that would have lead to the degradation of the barrier beach, ultimately resulting in a possible breach of the system.
By moving the accessway northward to a more stable section of the beach, vital access to the southern portion of Duxbury Beach Reservation’s property will be maintained while it also stabilizes and maintains the integrity of the barrier beach system.
The work was started and completed in a matter of weeks this spring. The old Crossover 3 area was backfilled to the same elevation and slope of the adjacent dunes to the north and south. The two existing sections of sturdy drift fencing (SDF) were connected by erecting an additional 28 feet of SDF to span the gap where the old accessway had been.
The probability of overwash (and damage to the integrity of the beach) in this new location is low due to the design of the new accessway.
The new 120-foot-long Crossover 3 is angled from NW to SE, perpendicular to the prominent winds in the area, to minimize storm surge and tidal flows through the accessway. In the highly unlikely event that a washover does occur in this area, the salt marsh on the bayside of the barrier will act as a natural water attenuator for storm surge.
Due to the dynamics of this new location, the risk of an overwash through the accessway is greatly reduced compared to its former location.
Moving Crossover 3 may also result in a lower impact on beach nesting birds. In its old location, the area hosted roughly 20% of the Duxbury Beach piping plover (PIPL) population and 25% of the Duxbury Beach least tern (LETE) population.
The new location is north of the PIPL and LETE activity in that section of the beach. The closest PIPL nest to the new access way location since 2018 was several hundred feet south of the new crossover.
Historically, there has been little nesting activity in the immediate area of the new crossover for either species. The theory is that the dense vegetation around High Pines and lack of bayside access deters birds from nesting in this area. Due to the saltmarsh west of the new crossover and lack of bayside foraging habitat, PIPL broods would be less likely to utilize the new accessway as a crossing location, further minimizing the risk to beach nesting birds.