Grassland Bypass Project

Background Information

Two sets of Waste Discharge Requirements (WDRs) apply to the geographic area known as the Grassland Drainage Area. They are for surface water discharges from the Grassland Bypass Project, which has been under WDRs since 1998, and groundwater discharges from the Grassland Drainage Area, which has been under WDRs since 2015.

WDRs for the Grassland Bypass Project

The Grassland Bypass Project has been under waste discharge requirements (WDRs) for surface water discharges since 1998. The dischargers for the project are San Luis & Delta-Mendota Water Authority and United States Department of the Interior, Bureau of Reclamation. Historically, subsurface agricultural drainage water (tile drainage) and surface runoff (irrigation tail water) from the Grassland Watershed was discharged to the San Joaquin River through Salt Slough and/or Mud Slough (north). With the start of the Grassland Bypass Project in 1996, all tile drainage from a 97,000-acre area known as the Grassland Drainage Area is consolidated. Today, irrigation season discharges are managed and reused within a portion of the Grassland Drainage Area called the San Joaquin River Improvement Project, and only storm season discharges may be discharged through the San Luis Drain to Mud Slough.

WDRs for Growers in the Grassland Drainage Area

The Central Valley Water Board Irrigated Lands Regulatory Program (ILRP) was initiated in 2003 as a conditional waiver of WDRs program to regulate discharges from irrigated commercial agricultural land to surface waters. As surface water discharges were already regulated under the Grassland Bypass Project WDRs, the growers in the Grassland Drainage Area were not regulated by the ILRP conditional waiver. In 2012, the Central Valley Water Board started issuing waste discharge requirements for discharges to surface water and groundwater for irrigated commercial agricultural land. The General Order for growers in the Grassland Drainage Area regulates discharge to groundwater and is similar to other ILRP general orders.

Selenium Control Program

Grassland Bypass Project Documents (surface water)

To request a copy of a submittal listed below, please reach out to the Program Contact listed under Contact Us.

  • 2021 Annual Monitoring Report (30 April 2022)
  • Memorandum: Leak into the San Luis Drain (27 April 2022)
  • 2022 Surface Water Pesticide Monitoring Proposal (16 December 2021)
  • Revised Grassland Bypass Project Technical and Monitoring Report Pursuant to California Water Code Section 13267 (14 December 2021)
  • January to June 2021 Electronic Data Deliverable (25 October 2021)
  • 2020 Annual Monitoring Report Memorandum (25 August 2021)
  • Grassland Bypass Project Technical and Monitoring Report Pursuant to California Water Code Section 13267 (28 July 2021)
  • Revised Drainage Management Plan (31 May 2021)
  • 2020 Annual Monitoring Report (30 April 2021)
  • Grassland Bypass Project data can be accessed through the California Environmental Data Exchange Network
  • Document Archive

Grassland Drainage Area Documents (groundwater)

To request a copy of a submittal listed below, please reach out to the Program Contact listed under Contact Us.

  • 2021 Annual Monitoring Report (1 May 2022)
  • Annual Management Practice Implementation and Nitrogen Application Report for the 2020 Crop Year (7 February 2022)
  • 2020 Annual Monitoring Report (30 November 2021)
  • Central Valley Groundwater Monitoring Collaborative Five-Year Assessment Report (30 November 2021)
  • 2021 Groundwater Quality Trend Plan Monitoring Network Update (16 June 2021)

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