Marys River is a tributary of the Willamette River located in the state of Oregon. It flows through Benton County and is approximately 30 miles long. The river is known for its scenic beauty and provides habitats for various wildlife species. The river's watershed includes several small streams and creeks, contributing to its flow. It is a popular spot for recreational activities such as fishing, kayaking, and hiking along its banks. The surrounding area features lush forests and farmland, making it an important ecological and agricultural resource for the region.