Original: The European discoverer of the Lachlan River in 1815 was Acting-Surveyor George William Evans, who named the river after Lachlan Macquarie, the Governor of the colony of New South Wales.
Simplified: The European who found the Lachlan River in 1815 was Acting-Surveyor George William Evans. He named the river after Lachlan Macquarie, the Governor of New South Wales.