Jersey's Val de la Mar reservoir to be emptied in 2011
Jersey's Val de la Mar reservoir will be emptied next summer to prepare it for a future extension.
There will also be restricted access for walkers while the work is done.
The Val de la Mare reservoir is Jersey's second biggest water storage area after Queen's Valley and Jersey Water said it may need to be extended.
It is planning to lay a tight membrane on the dam to prolong its life and to prepare for any future works that may be needed due to increased demand.
The reservoir will be emptied during the project in late summer 2011.
People will not have access to some public walking routes.
The company said the reservoir will be refilled once the work is done.