Most of these structures were installed to prevent beach erosion at the mouths of streams. All bulkhead data presented is provisional. No watersheds on the Island were systematically surveyed for bulkhead information, and the scope of Bulkhead Points presented in this map set is not intended to be comprehensive . Most of these points represent withdrawals for water supply, either private or public. All of these points are believed to be active withdrawals, and inactive withdrawals have been excluded.
Withdrawals can have a dramatic effect on fish distribution by reducing stream flow.
Withdrawals and associated structures may also physically block fish migration. All withdrawal data presented is provisional. No watersheds on the Island were systematically surveyed for withdrawal information, and the scope of Withdrawal Points presented in this map set is not intended to be comprehensive. This definition includes diversions, derelict water withdrawals, controlled channels, and logjams. All in-stream feature data presented is provisional.