Complex sentence: Triberg was however somewhat in trouble, since most tourists come to the waterfalls on a day tour base and Americans, which had been quite present before 9/11, ceded to come and stay and the formerly famous local watchmaker industry is nearly completely gone.
Split into simpler sentences: Triberg was however somewhat in trouble, since most tourists come to the waterfalls on a day tour base and Americans, who had been quite frequent before 9/11, ceased to come and stay. Also the formerly famous local watchmaker industry is nearly completely gone.