Complex sentence: It is not know how the "Falcon" came to be in Lake Washington but it has been speculated that the small-sized vessel could still earn a profit in operations on the lake when routes elsewhere became uneconomical.
Split into simpler sentences: It is not know how the "Falcon" came to be in Lake Washington. It has been speculated that the small-sized vessel could still earn a profit in operations on the lake when routes elsewhere became uneconomical.