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  What is a Watershed
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The Simple Defnition
A Big Bowl
Santa Barbara’s Watersheds
What Degrades a Watershed
 

The Simple Definition
It’s the area of land that catches rain and snow and drains or seeps into a marsh, stream, river, lake or groundwater.
You're sitting in a watershed now!
Homes, farms, ranches, forests, small towns, big cities and more can make up watersheds. Some cross county, state, and even international borders. Watersheds come in all shapes and sizes. Some are millions of square miles, others are just a few acres. Just as creeks drain into rivers, watersheds are nearly always part of a larger watershed.


A Watershed is a Big Bowl
Due to gravity, water runs downhill from high points like mountains and hills to lower points in lakes, rivers, ponds and wetlands. Eventually, all water drains into the world’s oceans. In every area of the Earth, the highest points of land form boundaries from which water runs downhill. Each area the water drains into is called a watershed. You can think of it as a big bowl with the high edges being the boundaries of the watershed. Smaller watersheds are contained in larger watersheds, like a stack of bowls that fit inside each other. Forty percent of the watersheds in the United States drain into the Mississippi watershed and then into the ocean in the Gulf of Mexico.

Watersheds, rivers, and oceans aren’t bound by town, state, or even country lines. By looking at a map you can see that the United States shares watersheds with Canada and Mexico. Once the water reaches the ocean, currents drive it to other parts of the world, so water truly does connect us all.

Everything that exists in a watershed affects the quality of the water in the watershed. If water runs through a mountain forest, it will pick up leaves, dirt or pine needles. If it runs through a pasture where cows graze, it will pick up bacteria or pollution from the wastes cows create. If it runs through a city or a neighborhood with a lot of people, it will pick up things people use such as food wrappers, plastic water bottles or lawn fertilizers. If it runs through factory or farm areas, it will pick up chemicals, pesticides, oil, fertilizers or other pollutants. The pollution, trash and materials water collects on its way through a watershed is called “runoff.” Rural farm areas, suburban neighborhoods and the urban areas of cities all have runoff. Urban runoff is the most severe, because cities have the most people, industries and factories. Runoff is a problem for all watersheds because the pollution it contains ends up in lakes, rivers, wetlands, estuaries and the ocean.

Santa Barbara’s Living Watersheds and Ocean
(Source: The Creeks Division of the City of Santa Barbara)
We all live in a watershed—land that is drained by a creek system that flows to the ocean. The health of our creeks and beaches is linked to the health of our watersheds.

Santa Barbara’s four main watersheds run north/south from the top of the Santa Ynez Mountains, down through Los Padres National Forest, through county areas and the city, and out to the beaches and ocean. They includes.

  1. Arroyo Burro on the west;
  2. Mission Creek through downtown;
  3. Sycamore Creek on the east; and
  4. Laguna Creek, nestled on the flats and now mostly below ground in pipes


The mountainous areas on the south side of the Santa Ynez ridge represent the upper area of the watersheds. Mostly within the Los Padres National Forest, they remain natural open areas, although dirt roads have cut across some sensitive habitats and unstable soils are causing some erosion and sedimentation in the creeks.

The mountains then drop steeply down toward the foothills and middle watersheds. Because of this steepness, water flows downhill very quickly during periods of heavy rainfall. Most of Santa Barbara is located within the lower floodplains which once included native riparian forests. Now home to more than 90,000 people, many areas of the city are developed with roads, parking lots, offices, shops and housing. These surfaces don’t allow water to percolate down into the ground. Instead, water runs off at high speed into creeks, which can overflow and make flood conditions worse.

What Degrades a Watershed?
A healthy watershed can be degraded by various physical conditions or human activities such as:

  • Large areas of impervious (paved) surfaces, reducing rainwater filtering and causing more runoff at faster speeds
  • Creek bank and channel erosion increases sediment that harmsaquatic life
  • Leaking sewer lines or septic tanks, which can increase bacteria levels
  • Littering and illegal dumping which pollutes creeks and the ocean
  • Storm drain conditions that cause back ups and flooding
  • Landslides due to unstable geology or human-induced instability
  • Invasion of non-native species, which leads to loss of native habitat
  • Loss of native landscapes which reduces wildlife diversity
  • Lack of natural shade along creeks, which increases water temperatures
  • Improperly graded dirt roads in natural areas cause erosion and sediment runoff
  • Wildland fires lead to erosion and sedimentation
  • Urban pollutants that are toxic to fish and birds and harmful to humans: oil and antifreeze from leaking cars, pet waste, fertilizers and pesticides, solvents, soaps and cleaners, and metals

SOURCE: The Creeks Division of the City of Santa Barbara

 

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