Your watershed and why it matters

Knowing what watershed you live in is an important piece of information for everyone who manages property, whether that property is an apartment, home, ranch or business.

To understand the watershed you live in is to understand the way water flows across the land, how much water is likely to drain across your land during flood season, and what might be in that water. It will help you know which weeds are likely to be troublesome and which wild animals might visit your property, whether you want them to or not.

You can look at the maps provided on this website to determine what watershed you live in, and if you need some interpretive help you can use some of the resources located on this website , which are also available by telephone, through a free Welcome to the Watershed directory/guide/publication and in person.  For additional information please contact the Solano County Resource Conservation District at (707) 678-1655.

Topography

Solano County covers 526,720 acres of land. Another 49,710 acres of the county is under some amount of water: creeks, ditches, streambeds, sloughs, or marshes. The type of soils that comprise that land and the way those soils are treated have a huge impact on the quality of nearby water sources, as well as the functionality of the land itself.

The western part of the county consists of hilly to very steep mountainous uplands of the Coast Ranges. The Solano County portion of these lands has a maximum elevation of 2,819 feet above sea level. The rest of the County lies on the floor of the Sacramento Valley. Except for an isolated area of low rolling hills in the southeast corner, the valley areas are level or gently sloping alluvial plains and marshes. The valley areas are near sea level along the eastern and southern borders of the county and rise to an elevation of about 100 feet at the foot of the mountains.

The Suisun Marsh, a large area of tidal flats and marshland is adjacent to Suisun Bay. This area has been cut into islands by a maze of natural drainage channels (sloughs).About two thirds of Solano county drains eastward to the Sacramento River and the rest drains southward into the Suisun Bay or Carquinez Strait.

Soil Types

Silt, sand, clay and organic material are the raw ingredients of soil, determining its texture and fertility. Soil scientists survey areas to determine soil type, location and potential uses.

Soil is classified by capability (suitability for growing field crops), ranging from Class I soils, which have few restrictions that effect their use to Class VIII soils, in which soils and landforms restrict their use to wildlife habitat, water supply, or recreation. Soil is also classified according to ability to provide wildlife habitat.  All of this information is necessary to understand and manage watersheds, wildlife habitat areas, recreational facilities, community developments and engineering projects.

Land Use

Human land use in Solano County is determined by soil type and water availability. The eastern half of the county is nearly level and is farmed with intensive irrigation. The western one-fourth is hilly to very steep and is used mostly as rangeland. The southeastern one-eighth is rolling to hilly and is used for dry-land small grain farming and pasture. The south–central one-eighth is marshland and is used mostly for waterfowl hunting.

Watershed Problems

Solano County is home to seven rapidly growing cities located variously on the valley floor, on the Sacramento River, on Suisun Slough, tucked up against the foothills of the Coast Range, and on the Carquinez Strait.

The eastern part of the county is a natural flood plain. Flood hazards result from soil type and the natural drainage patterns in the area, but the effects of manipulating waterways and urbanization impact the problem.
Flooding has an immediate negative effect on cultivated fields and cities, and it also carries long-term watershed health costs. After every storm, polluted runoff and sediment from farm fields end up downstream of the floodwaters, either on someone else’s field, or in the Sacramento Bay Delta System, via the Sacramento River, Suisun Bay, or Carquinez Strait, the eventual drains of every watershed in the County. The same thing happens when cities flood. All the contaminants from yards and flooded streets wash down the storm drains and eventually end up in the River or Bay.

In well-drained areas, flooding recharges the water table. If there are excess nutrients in the soil, flooding leaches (forces) those nutrients downward, resulting in leached soil nutrients unavailable to future crops, and contaminants in the ground water that can impair water quality and affect future users.

Land and Land Use Resources

• Solano County General Plan
  http://www.solanocountygeneralplan.net/index.htm

• Solano Napa Greenbelt Alliance
  http://www.greenbelt.org/regions/solanonapa/index.shtml

• Solano Land Trust
  http://www.solanolandtrust.org/

• USGS Access San Francisco Bay and Delta
  http://sfbay.wr.usgs.gov/index.html