Lower Salinas River Watershed Nutrient TMDL - Implementation and Monitoring Progress

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A watershed-related topic examined by the ENVS 560/L Watershed Systems class at CSUMB.

Image 1. Lower Salinas River Watershed: Nutrient TMDL Project Area


This page summarizes the implementation and monitoring that has occurred following adoption of the Lower Salinas Watershed Nutrient TMDL. The TMDL plan for the Lower Salinas River Watershed was approved by the Central Coast Water Board on March 14th, 2013 [1], and by the EPA on October 13th, 2015. The proposed implementation strategy includes complying with the Central Coast Region Agricultural Waiver. Also, 72 monitoring sites were developed within the watershed. These sites are managed by the Central Coast Ambient Monitoring Program. Any available monitoring data is available here Lower Salinas River Watershed TMDL - Monitoring Data.


Pollution of surface and groundwaters from nitrate and unionized ammonia has been a long standing problem for the lower Salinas Valley. Monitoring data in the Lower Salinas River Watershed indicate excessive levels of nitrate, unionized ammonia, and associated nutrient-related problems including, excessive orthophosphate, low dissolved oxygen, toxicity and excess algal biomass.[2] Nitrate loading from the Salinas River has been identified as a potential driver of algal blooms occurring immediately after "first flush" events, the first rain after a period of drought [3]. The California Central Coast Water Board is required under the Federal and State Clean Water Act to protect and regulate beneficial uses of these waters. The Lower Salinas Valley Watershed has a wide range of beneficial uses which are not being supported including aquatic habitat, drinking water supply, groundwater recharge, agricultural supply, and water contact recreation. Water Supply and aquatic habitat constitute the most sensitive applicable beneficial uses requiring the most stringent water quality standards.[4] Development of the Lower Salinas Valley Watershed Nutrient TMDL was intended to reduce and eventually eradicate nitrate pollution for the purpose of human health, the Central Coast Water Board's top priority.

Action Taken since TMDL Approval

Map of The Lower Salinas River Watershed nitrate measurements and possible sources (from CCRWQCB 2012 draft TMDL report)

Proposed implementation actions (section 7.3.3 in 2013 nutrients TMDL) include compliance with the Central Coast Region Agricultural Waiver (Ag order--Order No. R3-2012-0011) with the overarching goals of:

  • "Control[ling] discharge of nutrients to impaired waterbodies and
  • "Implement[ing] management practices capable of achieving interim and final Load Allocations identified in [the latest (2012)] TMDL".

Irrigated agriculture has been identified as the dominant source contributing to the issue of nutrients in the LSRW. Regulations can follow those set forth in the Ag Waiver. It is also advisable for Water Board staff to incorporate educational outreach programs to encourage the adoption of Best Management Practices (BMPs) on all croplands.

Initial Implementation

The TMDL is implemented through the Conditional Waiver of Waste Discharge Requirements for Discharges from Irrigated Lands (Ag Order) which clearly requires dischargers implement, and where appropriate update or improve, management practices, which may include local or regional control, treatment practices and changes in farming practices to control discharges, meet water quality standards and achieve compliance. If the discharer fails to address water quality they may be subject to progressive enforcement and possible monetary liability. [3] More information regarding dischagers requirements and expectations can be found on the Conditional Waiver of Waste Discharge Requirements for Discharges from Irrigated Lands (Ag Order) page.


For complete list, see TMDLs in the Monterey Bay Region of California.

TMDL Projects Currently in Development for the Lower Salinas Valley (2015-2016)

Water Quality Monitoring

The Central Coast Regional Water Quality Control Board (CCRWQCB) has designated Central Coast Water Quality Preservation, Inc (Preservation, Inc.) as the main non-profit entity to conduct the Cooperative Monitoring Program in compliance with the Ag Order (Order no. R3-2012-0011). Under this order every enrolled grower may conduct their own surface water quality monitoring, or participate in the Cooperative Monitoring Program (CMP). Over 99% of growers have opted to participate in the Central Coast Ambient Monitoring Program (CCAMP).

The Central Coast Ambient Monitoring Program (CCAMP) conducts monthly monitoring in the Lower Salinas Watershed in order to conduct trend analysis and detect emerging water quality problems.

The Central Coast Water Board's goal is to have all water bodies meet, or under, target TMDL levels by 2025 Total Maximum Daily Loads for Chlorpyrifos and Diazinon in Lower Salinas River Watershed in Monterey County, California 2011.

As of March 2020, no public monitoring reports have been released; but monitoring data is available.

The Central Coast Water Board is scheduled to review the TMDL by 2024 in order to recognize new monitoring data and research within the Lower Salinas River Watershed.(Lower Salinas River Watershed TMDL - Monitoring Data) [5]



  1. Lower Salinas River Watershed Nutrient TMDL Information https://www.waterboards.ca.gov/centralcoast/water_issues/programs/tmdl/docs/salinas/nutrients/
  2. RWQCB Lower Salinas River Watershed Nutrient TMDL Staff Report
  3. 3.0 3.1 Conditional waiver of Waste Discharge Requirements for Discharges from Irrigated Lands
  4. TMDL for Nitrogen Compounds and Orthophosphate in the Lower Salinas River Watershed Factsheed #1
  5. Concise Tabular Summary for the Lower Salinas River Watershed TMDL http:://my.reference.link.com


This page may contain student work completed as part of assigned coursework. It may not be accurate. It does not necessary reflect the opinion or policy of CSUMB, its staff, or students.