Lowland Watersheds

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Lowland Watershed

Lowland watersheds drain the rain on the glacial plateau to floodplains or Puget Sound

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Lowland watersheds are located within the rain-fed glacial plateau surrounding the Salish Sea. Their streams flow into floodplains or into embayments along shorelines. They are different that headwaters in that precipitation falls as rain, and topography is defined by our glacial history, with many wetlands.

There have been limited attempts to classify lowland catchments into types, that could guide assessment and stewardship. However familiarity with multiple systems suggests some general forms. Most lowland watersheds include some sections where water flows among glacial troughs and swales, where the current stream is not responsible for the shape of the landform. In the lowlands, large areas of glacial plateau are typically a few hundred feet above sea level. Historically these areas likely supported extensive beaver wetlands, and stored a tremendous volume of winter rain. Such glacial plateau headwaters then descend to either a floodplain or shoreline through some kind of ravine. This plateau-ravine pattern may repeat several times in a system, and generally indicates the geologic youth of our post glacial landscape. Some larger basins have begun to develop a larger and more gently sloped floodplain valley near the lower reaches (for example Jimmycomelately Watershed) These are the large stream valleys, which are intermediary between the multitude of small streams, and the 16-20 large floodplain systems. In some cases, a stream is strongly associated with a large historical floodplain where agricultural development may have created more of a stream than was there historically (for example French Creek Watershed). It might be a useful project to clarify these systems, and better characterize their form and potential ecological functions and services. The Puget Sound Characterization Project does some of this work, but does not provide a multiple scale analysis.

Lowland Watershed Topics

The following topics are related to lowland watersheds:

Lowland Watershed Places

The following pages describe places among lowland watersheds:

Catchment Scale

Lowland Watershed Efforts

The following efforts are being implemented by workgroups in lowland watersheds:

Lowland Watershed Documents

The following pages cite documents about lowland watersheds:

The following lowland watershed documents are uploaded to this wiki: