Healthy Creeks, Healthy Bay

All of the water flowing through the San Lorenzo Creek watershed flows directly to the Bay without any treatment. The effects of urbanization—soap from washing cars, pesticides, herbicides, oils from cars, trash and other pollutants—have a direct impact on the water quality of creeks and the Bay. Healthy creeks have:

• Cool water. Critical for aquatic life, cool water is less prone to oxygen-reducing algae and keeps down nitrate levels, which can be toxic to fish.
• Clean, clear water. Low turbidity (less sediment or a low level of cloudiness) means higher oxygen concentrations for aquatic plants and animals. Fine sediments bury aquatic insects and fish eggs and fill in pool habitat. Even yard waste (such as leaves and lawn clippings) will contribute to cloudiness and use up oxygen as it decomposes.
• Abundant and diverse native vegetation. Overhanging plants provide habitat, shade to keep water cool and soak up runoff water. The roots help stabilize soil and control bank erosion. Non-native species such as eucalyptus trees, ivy, periwinkle and arundo, can have a negative impact on water quality, out-compete natives and contribute to soil erosion.
• A variety of pools and riffles. Varying flow conditions add oxygen to the water and provide habitat nooks for fish and insects.
• A rocky creek bed. Cobble and gravel reduce erosion of the creek bed and provide spawning grounds for fish.
• Woody debris along creek banks. Natural debris from vegetation supports the aquatic food chain and provides habitat for fish and invertebrates.
• Thriving native populations. Fish, amphibians and aquatic insects populations naturally balance creeks.