Cornwall Council as the 'Coastal Protection Authority' is responsible under the Coast Protection Act (1949).
As Risk Management Authorities:
The Environment Agency manages flood risks from the sea and
Cornwall Council manages coastal erosion. The Environment Agency plays a strategic overview role.
The Shoreline Management Plan (SMP)
The main policy document for the future management of the coast is the Shoreline Management Plan (SMP).
The South West Coast Group represents coastal management authorities. The region includes organisations from Dorset, around Cornwall's coast and up to Somerset. They then report to the South West Regional Flood and Coastal Committee ((SWRFCC). They report to Central Government through DEFRA.
Most issues can be resolved online, it's the quickest and most convenient way to get help.