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Taking Care of Our Watershed

The Watershed Components

No matter where you live you’re part of your local watershed. Creeks, like streams and rivers, collect water from a surrounding watershed. The shape and slope of the landscape, the climate, the rainfall amounts, the vegetation, the soil types, as well as human activities, can all affect the character of a watershed. All of these factors impact the rate water runs through each creek. Rain falling on a watershed flows as surface runoff to rivers and streams, or filters down through soils to flow into the groundwater aquifers. Both surface and groundwater flows can pick up pollutants and carry them into our creeks. In the San Pablo Creek watershed water flows into the creek and its tributaries – Appian, Wilkie, and Castro creeks among others, and eventually to San Francisco Bay. Even the unnamed creeks, which may be dry in summer, are an important part of the watershed.

Both the waste water system and the storm drain system affect our creeks and water quality. Waste water (water that is flushed down the drains in our homes and businesses) is collected in underground pipes and transported to the municipal treatment plant. Treatment removes fecal coliform bacteria and organic solid wastes. However, not all toxins are removed. Certain household hazardous wastes like paint or garden chemicals are not removed and should not be poured down household drains.

A separate system, the storm drain system, collects rainfall and water that flows from lawns, gardens, sidewalks, and roads and carries it directly to the creeks and Bay. Storm drains are along the sides of streets near curbs.

Pollution from many indirect sources is called Non-point Source Pollution. Common examples of Non-point Source Pollution include: eroding soils, oil, paints, solvents, anti-freeze and pesticide spills along our roads or into our storm drains. These pollutants which flow into our storm drains go untreated directly into our creeks. They are harmful to wildlife and to people. By being aware of these damaging pollutants and by properly maintaining our gardens and yards we can protect the water quality and the health of San Pablo Creek.

Watershed Stewardship Household Activities


What you can do at home to help maintain the health of your watershed.


The following household maintenance and gardening tips will help protect the water quality of San Pablo watershed while maintaining the beauty of your yard and garden.

Don't pour or wash any automotive fluids such as motor oil or antifreeze down gutters or storm drains.


Wash vehicles and equipment with water only on dirt or grass, where soapy water won't run off into the street or storm drains. Better yet use your local car wash.

Drive less! Auto exhaust particles, leaking fluids, and tire and brake pad debris are major sources of Bay Area water pollution.

Proper gardening techniques can also protect the soil, help retain rainfall, and protect a creek’s water quality.

Plant your vegetable garden and ornamentals on level areas away from the creek banks. Keep garden debris such as grass clipping, leaves, and pruning debris out of the creek and off its banks. Garden debris decomposing in the creek reduces the available oxygen content for aquatic life. In addition, garden fertilizers should not be allowed to migrate into any creek because they also will increase algae growth and reduce the available oxygen for aquatic life.

Garden debris can be composted easily for reliable soil amendment or can be curbside recycled. For information on composting, go to: http://www.cccounty.us/depart/cd/recycle/compost.htm

Appropriate landscaping can reduce water runoff and erosion, lessen the need for fertilizers and pesticides, and reduce overall water consumption.

Among the best and most beautiful plants a gardener can grow are our own natives. California's native plants evolved here over a very long period, and are the plants that the first Californians knew and depended on for their livelihood. Our native plants have co-evolved with animals, fungi and microbes, to form a complex network of relationships. These plants are the foundation of our native ecosystems, or natural communities.

Our native plants, having evolved here, are best suited to perform the macro tasks that plants do, such as manufacturing oxygen and filtering impurities from our water. These plants also do the best job of providing food and shelter for native wild animals. Native plants are also a major element in the natural beauty for which California is famous.

When non-native plants spread and become established in wild areas, they are referred to as "naturalized." Some of these plants, such as forget-me-nots and field mustard are widespread, but generally do no great harm. Others take over natural areas and out-compete or smother native plants. They can do this because the natural pests, diseases or weather conditions, which kept the plants in check in their homeland, are missing in California. These weeds deprive our wild animals of food and shelter, since native animals cannot make much use of them. Weeds do damage in waterways, as well as on dry land, clogging water flow and choking out aquatic plants essential to wildlife.

By replacing these invaders with suitable native plants, you can create a low-maintenance, erosion-resistant landscape that's friendly to wildlife. For ideas on gardening with native plants, visit the Spawners demonstration garden at the El Sobrante Library. Another resource is the California Native Plant Society website at: http://www.cnps.org/


Try to eliminate non-native plants before they become established.

The most common invasive non-natives in this watershed are:


  • Cape or German ivy (Senecio mikanoides). This twining climber from South Africa has bright green, shiny, ivy-like leaves that smell foul when crushed; fluorescent pink young stems; and small yellow flowers in winter. It forms dense masses that shade out all other plants and spreads rapidly from seeds or fragments. Pull up the plants, shallow roots and all. Seal all plant parts in bags and dispose of them in the trash (not in the compost pile). Wild cucumber is a similar-looking native vine that should be preserved. Its leaves are slightly hairy and their color is more blue-green than ivy's. With white flowers and fine curly tendrils, wild cucumber does not form dense mats. ( http://en.wikipedia.org/wiki/Delairea )
  • Cardoon, artichoke thistle (Cynara cardunculus). Cardoon is dramatic, forming tall fountains of large, gray-green, deeply divided leaves and huge blue-purple thistle-like flowers. Originally a garden vegetable or ornamental, this plant has gone wild, developing fierce spines that are dangerous to both people and animals. Its flowers shed thousands of seeds, which are carried widely on the wind. Wearing heavy gloves, you should dig up the roots as soon as possible. Don't worry about digging up the wrong plant: All large local thistles are invasive weeds. To prevent the plant from spreading, cut the flowers and buds and dispose of them in sealed bags. Even after being they'll form mature seeds. Don't grow cardoon in gardens.http://en.wikipedia.org/wiki/Cardoon )
  • Pampas grass, jubata grass (Cortaderia selloana, Cortaderia jubata). These grasses grow tall, to six feet or more, with dramatic white seed plumes. Crowding out native vegetation without providing food, they are also a fire hazard. Seeds carry widely on the wind and spread more clumps. Dig up these clumps (once they are large, this is difficult). To prevent spread, cut off plumes and dispose of them in a sealed trashcan. Don't grow these plants in gardens.   ( http://en.wikipedia.org/wiki/Cortaderia_selloana  )
  • Algerian and English ivy (Hedera). These woody evergreen vines have leathery, dark-green, three-pointed leaves. Algerian ivy, with pinkish stems and less distinct leaf points, is more invasive than English ivy. These ivies are handsome and tough, but they shade out everything else, climb and kill trees, and provide useful habitat only to rats. Wearing gloves (some people are allergic), pull ivy up roots and all; the dense cover can be rolled up like a rug. Don't let it root again. On trees, cut woody stems growing up trees and pull off a few feet so that the ivy above will die. ( http://en.wikipedia.org/wiki/Hedera_helix )
  • Himalayan blackberry (Rubus discolor). This common shrub has toothed, divided leaves; long reddish weeping canes that root where they touch ground; pale pink single flowers; edible black berries; and sharp, painful thorns. (Native blackberry, which should be preserved, has dense, almost furry prickles that hardly hurt if you grab them.) Himalayan blackberry provides food for birds and people, and nest spots safe from cats and squirrels, but it takes over large areas if left unchecked. Wearing heavy gloves, cut the canes so that you can get close and then dig out the roots, especially woody burls that will sprout new canes. Dispose of the plants where its parts can't root. http://plants.usda.gov/java/profile?symbol=RUAR9 )
  • Vinca or periwinkle (Vinca major) This trailing perennial has stems that root where they touch ground; shiny dark green leaves; and lavender blue, five-petaled flowers. In shaded creek areas it is extremely invasive.  http://en.wikipedia.org/wiki/Vinca_major

Never dump oil, antifreeze, paint, solvents or pesticides into the soil or storm drains. Dumping these wastes is both illegal and dangerous.


Go to: http://www.co.contra-costa.ca.us/depart/cd/recycle/illegal-dumping.htm to report pollution and illegal dumping incidents.


Many of these wastes are recyclable. Learn more at Contra Costa County Household Hazardous Waste Website: 

http://www.co.contra-costa.ca.us/depart/cd/recycle/options/v5951.htm .

Use garden and lawn chemicals sparingly and never when it is windy or raining. Lawn chemicals can be carried by the wind or water runoff into creeks. Read pesticide labels carefully. Pesticides and herbicides are toxic to people, pets, wildlife and fish. A properly chosen ornamental plant and, especially, a California native plant can be more pest resistant and require less chemicals and fertilizers to survive.

  • Encourage beneficial insects such as ladybugs, praying mantises, lacewings, and ground beetles.
  • Use less toxic pesticides such as soap and water solutions or insecticide oils before using more costly and toxic insecticides.
  • Consult with your local nurseryman or Master Gardener ( http://ccmg.ucdavis.edu/ ).