Urban stormwater management in the City of Watsonville

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The City Of Watsonville's storm drain system directs runoff through a network of underground pipes that eventually discharges into the Monterey Bay. This system includes 2000 storm drain inlets, 50 miles of pipeline, and 15 storm water pumps located along Corralitos Creek and the Pajaro River which is currently listed as an impaired waterbody in the 303 d list. The system was originally designed to control flood events.[1] The untreated storm water runoff drains directly into the ocean.

Regulatory Background

Many federal, state and local laws and policies have been implemented and enforced over the last few decades to reduce pollutants and contaminants being discharged into the Pajaro River, and the Watsonville Slough Complex.

Federal Regulations

For background on federal regulations, see Urban stormwater regulations applicable to central coast region.

State Regulations

For background on state regulations, see Urban stormwater regulations applicable to central coast region.

Local Regulations

The City of Watsonville specifies in its municipal code how stormwater runoff must be addressed or mitigated, but most of the details are spelled out in other documents. An example section in the municipal code is:

(§ 1, Ord. 1088-00 C-M, eff. April 14, 2000)
6-3.530 Control of storm water run-off flow rates
"All development shall not cause higher rates of storm water runoff than those that existed prior to project." [2]

The specific implementation of Watsonvilles' stormwater-related codes is outlined in their Storm Water Management Plan. The Storm Water Management Plan best management practices (BMPs) that are outlined in the city's low impact development design guide which designates a "common hydromodification control standard" with the Central Coast Regional Water Quality Control Board. [3]

Annual Review

Watsonville submits an annual review of the Storm Water Management Plan's and BMP's effectiveness in addition to suggested improvement opportunities to achieve the Maximum Extent Practicable (MEP) that are required under Phase II permit requirements.

Watsonville's Annual Reports:


  • 1997 Current Industrial Activities Storm Water General Permit
  • 1999 Phase II of Section 402 of the Clean Water Act requires cities under 100,000 to implement SWMPs
  • 2005 City of Watsonville implements 2005 Urban Water Management Plan [1]
  • 2009 Storm Water Management Plan approved.
  • 2010 City of Watsonville revises the 2005 Urban Water Management Plan [2]
  • 2011 Water Quality Control Plan for the Central Coastal Basin

Resources at Stake

A large percent of the population relies on the continued health and vitality of the agricultural industry for their livelihood. Left unmitigated, stormwater problems pose an ongoing threat to agriculture. Past incidences of E.coli contaminated lettuce from the region have had serious economic impacts.[4]

The Watsonville Slough system is comprised of Harkins, Gallighan, Hanson, Struve, and Watsonville Sloughs and drains an area of approximately 50 km2 (13,000 acres).[5] This area contains significant and diverse coastal habitats including, salt marsh, brackish and fresh water marsh making the Watsonville Slough a valuable resource for both coastal plant communities as well as fish and migratory birds.

Related Projects

Salsipuedes Creek Capacity Enhancement & Restoration Project: City and County staff are partnering with the US Army Corps of Engineers to receive early feedback with regard to permitting the project which will address potential flooding caused by stormwater runoff. Corps staff are in the process of securing permits for the project along the creek. The process requires preparation of 70% complete design plans for the project and a hydraulic bank stability assessment, to be completed by Northwest Hydraulic Consultants, Inc. (NHC)[6]



  1. City of Watsonville Sewer/Storm Drains
  2. http://www.codepublishing.com/ca/watsonville/ City of Watsonville municipal code
  3. Low Impact Development Best Management Practices Design Guidance for Hydromodification Management and Stormwater Quality
  4. Flynn, Dan. E. coli-Contaminated Lettuce Came from a California LGMA Grower. 2013 Jan 15. www.foodsafetynews.com
  5. Non-Point Source Program - CCA NPS Watershed Assessment for Watsonville Slough
  6. Northwest Hydraulic Consultants, Inc



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