A watershed is a basin, or a land area that collects and delivers water to a central point. Water moves through a watershed through soils, streams and rivers from upper elevations to lower elevations, and exists at an outflow such as a stream, river, lake, or the ocean. Watersheds are complex and unique containing different topographies, soils, vegetation and land-uses. Watersheds are affected by climate changes that are altering the quantity, quality, timing and distribution of water. The cumulative impacts of past land-uses, water withdrawals, and disturbances in a watershed are all exacerbated by climate changes. Changes vary by scale and location in a watershed, but affect the management of downstream uses, and may present challenges to those seeking to manage watersheds for water quality or supply; protection of cultural resources; biodiversity; productive timber; recreation; or the provision of habitat for wildlife and rare species.