San Diego Citizen Watershed Monitoring Consortium Saturday, 11th October 
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SDCWMC > Watersheds

Peñasquitos Watershed

Map of Penasquitos watershed


The Los Penasquitos Hydrologic Unit (906) is comprised of the Los Penasquitos Creek watershed (906.10 - 906.20), several coastal tributaries (906.30), and the Mission Bay watershed (906.40 - 906.50). These watersheds drain a highly urbanized region located almost entirely west of Interstate 15 in coastal San Diego County. Collectively and individually, they support a variety of water supply, economic, recreational, and habitat-related beneficial uses. The major receiving waters, Los Penasquitos Lagoon and Mission Bay, are both fragile systems that support diverse native fauna and flora. Both water bodies are especially sensitive to the effects of pollutants due to restricted or intermittent tidal flushing.

The Los Penasquitos Creek watershed encompasses a land area of approximately 100 square miles including portions of the cities San Diego, Poway, and Del Mar. The watershed is highly urbanized with a population of approximately 400,000 residents. The creek discharges to a 0.6 square mile lagoon that is identified as an impaired water body on the California 303(d) list for sedimentation.

The Mission Bay watershed drains an area of approximately 80 square miles. Rose Creek and Tecolote Creek are the main tributaries to the Bay, which was converted from a coastal marshland in the 1940s after the completion of a large dredging project. Much of Mission Bay is adversely affected by coliform bacteria inputted by urban runoff and sewage spills, which are discharged by the main tributaries and smaller conveyances draining the watershed. Tecolote Creek is identified as an impaired water body on the California 303(d) list for a host of pollutants including coliform bacteria, trace metals, and toxicity.
Hyrologic Areas: Miramar Reservoir, Poway, Scripps, Miramar, Tecolote
Major Water Bodies: Los Penasquitos Creek, Los Penasquitos Lagoon, Rose Creek, Tecolote Creek, Mission Bay, Miramar Reservoir

If you would like to select one of these major water bodies as your collection site, follow these instructions to get the information you will need for the registration form:

  • Copy the name of the water body (e.g., San Marcos Creek).
  • Go to www.topozone.com and paste the water body name in the place name field.
  • Select CA and click the Search button. The results will look similar to the screenshot below: www.topozone.com results for San Onofre Creek

    The information you will need to write down or copy from the results are:

    • Type: the water body type.
    • USGS Quad: the Nearest City field on the registration form.
    • Lat: the latitude.
    • Lon: the longitude.
  • Enter the information into the Collection Site Information section of the registration form.

If you need assistance in selecting a collection site, please contact us. We'll be happy to help you find a site that's as close to your group' or school's location as possible.