Mercer Island beats Lakes | Girls prep water polo The Mercer Island girls water polo team logged a win in the pool on Wednesday, April 17. By Megan Managan • April 18, 2013 12:52 pm The Mercer Island girls water polo team logged a win in the pool on Wednesday, April 17. The team beat Lakes 7-5 in a non-conference match. The Islanders will take on Newport on Friday, April 19 in a 4 p.m. match at the Newport Hills Pool.