No. By the end of the Bronze Age about 850 BC, in most areas also the use of lake dwellings end as way of settlement at the water. Celts can first be proven from about 500 BC, so 350 years after the end of the lake dwelling Era. The quite clearly preferred ‘land life’ – often, they constructed their villages or fortified settlements even on the top of hills. But there are in Scotland and Ireland so called crannogs – fortified houses in or above the water.