Watershed Protection Program What is a Watershed? Protecting Your Watersheds Watersheds of San Mateo County Current Projects Construction in Sensitive Areas Flood Control Downloadable Resources Photo Gallery Affiliates
Watershed Protection Program
HickmansCinquaPNG.png

*Website is currently under construction.*

The Department of Public Works is committed to protecting the natural resources and scenic beauty of San Mateo County. Watershed Protection Services provides information, training and resources to support this commitment. Watershed Protection Services staff provide information and support to Public Works and its contractors, other County departments, outside agencies and members of the public.

 

Illegal Dumping

Report Illegal Dumping and Discharges to the County of San Mateo - Environmental Health Division. (650) 372-6200

Click here for more information.

What is a Watershed?

What is a Watershed?

A watershed is an area of land where all the surface water and underground water drain to the same location. Typically, watersheds are separated by geological features such as mountain ridges and drainage divides. Therefore, it is possible to have two watersheds right next to each other but the water in each watershed is independent of one another with regards to flow paths and endpoints. Watersheds can be comprised of natural and artificial waterbodies. Natural waterbodies include streams, lakes, ponds, and springs. Artificial waterbodies are man-made and include reservoirs, ditches, irrigation ponds. channelized streams, and harbors. These artificial waterbodies are the result of either altering a natural waterbody (e.g., damming a stream to form a reservoir) or creating an artificial waterbody from non-water-related features (e.g., digging a pond and importing water from an outside source). The graphic below is a simplified diagram of a single watershed. Notice how the runoff, streamflow, and groundwater end up in the same location?

Diagram of a watershed

 

Ground Water

Another side to watersheds that most people often overlook is the groundwater underneath the ground, roads, and floors that we walk on. When rain falls onto the ground, the water seeps into the soil and rock, saturating the substrate and raising the watertable. This groundwater may eventually make its way into what is known as an aquifer. An aquifer is a layer of porous rock and soils which conveys subsurface water movement. You may have heard of a percolation pond. These ponds are artificially built to allow water to seep into the water table and are typically found in cities which have extensively covered the ground with hard surfaces like roads and pavement. Many private and publicly funded water agencies operate wells that extract water from the aquifer to be treated and distributed to cities and towns.

Why Protect Watersheds?

As we discussed earlier, a watershed is not just a stream. It is all of the land that funnels surface water into the water way. Several wildlife, fish, and plant species live in and depend on the land and water of a functional healthy watershed. Watersheds provide a number of resources to all sorts of people. The watersheds of San Mateo County provide water for agriculture and municipal water treatment plants, scenic and aesthetic value for recreation and ecotourism, hunting and fishing opportunities and more. From everyday city dwellers to the avid outdoors person, one can find a little of everything to enjoy from a healthy thriving watershed. Click here for more information.

Protecting Your Watersheds

Why Protect Watersheds?

As discussed in the watershed section, a watershed is not just a stream. A watershed is all of the land that funnels surface water into the water ways which often includes multiple creeks and tributaries. Several people, wildlife, fish, and plant species live in and depend on the land and water of a functional healthy watershed. Watersheds provide a number of resources to all people as well as the environment. The watersheds of San Mateo County provide water for agriculture and municipal water treatment plants, scenic and aesthetic value for recreation and ecotourism, hunting and fishing opportunities and more. From everyday city dwellers to the avid outdoors person, one can find a little of everything to enjoy from a healthy thriving watershed.

How to Protect Watersheds

One of the primary threats to a healthy watershed is water pollution. The storm drain infrastructures found beneath our roads and buildings were designed to divert excessive storm water from these these urban areas to nearby creeks and drainages. Unforunately these storm drain infrastructures also allow for pollutants to travel towards creeks and rivers. A water pollutant is essentially anything that is not stormwater. Examples include but are not to limited to: tap water, soil, paint, soap, and garbage. A good rule of thumb is to only let storm water into the storm drain. Here is a quick list of actions you can take to protect your local watershed.

  • Avoid washing vehicles on the street with phosphate based soap products.
    • More than likely there is a storm drain system on the road that will carry the soap and water into the nearby creek or drainage.
  • Only let storm water in the storm drain.
    • The creeks and waterways in a watershed function as multiple ecosystems.
  • Choose native plants for the garden or landscaping.
    • Native plants are adapted to the climate and environmental conditions of San Mateo County. Non-native plants will often require more watering, fertilizer, and care. 
Watersheds of San Mateo County

COUNTY WATERSHEDS

San Mateo County exists on the San Francisco Peninsula and is essentially divided by the Santa Cruz Mountain range with the San Francisco Bay to the east and the Pacific Ocean to the west. Historically, the bay side has provided forgiving climate, flat topography, and connectivity with San Francisco and Santa Clara Valley. Conversely, the coast side presented relatively harsher climates and mountainous terrain. Today there is an obvious difference in the amount of urban development between the San Mateo coast and bay sides. The bay side has experienced high amounts of urban development which required flood control modifications within nearby watersheds. Streams that once naturally flooded and meandered around hillsides before reaching the San Francisco Bay were hardscaped and straigtened into channels. However, the coast side of San Mateo County is mostly comprised of open space and agriculture land with sparsely distributed towns. The majority of watersheds on the coast side have little to no flood control modifications; however, water diversions, lack of riparian zone management, and water quality issues present challenges for these precious resources. 

 

WATERSHED NAVIGATOR

What watershed do you live in? Use our watershed navigator to learn more about your local watersheds. The watershed navigator is an interactive map which allows the user to learn more about a specific watersheds by clicking within the watershed boundary. For more information on bay side watersheds within San Mateo County including watershed maps, locations, and historical information, visit the interactive Guide to San Francisco Bay Area Creeks produced by the Oakland Museum.

Pescadero MarshGazos Creek Watershed Pescadero MarshPilarcitos Creek Watershed Pescadero MarshPescadero Creek Watershed Pescadero MarshColma Creek Watershed Pescadero MarshSan Francisquito Creek Watershed Pescadero MarshSan Gregorio Creek Watershed Pescadero MarshSan Mateo Creek Watershed Pescadero MarshBelmont Creek Watershed Pescadero MarshAtherton Creek Watershed
Current Projects

Pescadero Creek Watershed

Solutions to Flooding on Pescadero Creek Road Study  More Information

Butano Creek at Pescadero Creek Road Sediment Removal ProjectMore Information

Pescadero Water Supply and Sustainability ProjectMore Information

 

Other Projects

Green Street Improvement Project                  More Information

Construction in Sensitive Areas
Flood Control
Downloadable Resources
Photo Gallery
Photo Gallery A school of three-spined sticklebacks floating in a sunlit eddy of a stream.

A school of three-spined sticklebacks floating in a sunlit eddy of a stream.

San Gregorio Creek

San Gregorio Creek at the Stage Road Bridge.

Tree Frogs

Pacific chorus frog larvae and metamorphs basking along the warm shallow edge of a pool.

Affiliates