"Laches is an equitable defense based on the principles of equitable estoppel." City of Cheney v. Bogle , 2008 WL 1904177, at *10, 2008 Wash.App. LEXIS 999, at *26 (May 1, 2008). Laches applies where there is (1) knowledge of or reasonable opportunity to discover a cause of action, (2) unreasonable delay in commencing that cause of action, and (3) damage to the defendant resulting from the unreasonable delay.