Drainage

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As a part of its operating system, IID maintains an extensive gravity flow drainage system. The lateral drain system is laid out to provide a drainage outlet for each governmental subdivision of approximately 160 acres and, as such, the drains usually parallel the canals.

The district is obligated to provide its drains at sufficient depth - generally 6 to 10 feet deep - to accept tile drain discharge. Where the drain cannot be maintained at sufficient depth, a sump and pump are provided and maintained by the district. These drains are used to collect excess surface flow (tailwater) from agricultural fields, subsurface tile discharges and operational discharge from canals and laterals.

There are over 1,450 miles of surface drains that can be divided into three main areas: Alamo River System, New River System and drains that flow directly into the Salton Sea. Approximately 430 control structures are installed along the drainage system.

Drainage Water Quality
Under its Colorado River Basin Irrigated Lands Regulatory Program, the California Colorado River Basin Water Board – Region 7 regulates irrigation and stormwater discharges from irrigated agricultural lands by issuing Conditional Waivers of Waste Discharge Requirements. The conditional waivers regulate discharges that could directly or indirectly affect the quality of waters of the state. Conditional waivers apply to owners and operators of irrigated lands and to drain maintenance operators, that is to growers and to IID.

Each waiver has a set of conditions that need to be met. In general, agricultural dischargers need to complete the following actions to comply with the conditional waivers:

  • File a Notice of Intent (NOI)
  • Develop a Water Quality Management Plan
  • Implement management practices to protect water quality
  • Develop and implement a Surface Water Monitoring and Reporting Program
  • Pay a state fee

Agricultural dischargers may choose to comply with the conditional waiver individually or by joining a coalition group, and most Imperial Valley growers chose to comply as a coalition group.

In January 2015, the Regional Board adopted Order R7-2015-0008, a “Conditional Waiver of Waste Discharge Requirements for Agricultural Wastewater Discharges and Discharges of Wastes from Drain Operation and Maintenance Activities within the Imperial Valley, Imperial County, California”. The waiver is good for five years; however, being conditional, means that the water board can revoke the waiver at any time (UCNFA News.  September 2, 2015). The conditional waiver program supersedes the conditional prohibition Total Maximum Daily Load/TMDL program.

In May 2016, IID submitted a revised drain water quality improvement plan, DWQIP Version 1.2 to meet the conditional waiver requirements. Under Version 1.2, many of the monitoring requirements and available management practices remain unchanged from earlier versions. The most substantial changes are the addition of a coalition group compliance program for agricultural dischargers to obtain regulatory coverage and the state fee, which is collected and paid by IID as a service to local growers.

In accordance with the provisions of the 2016 DWQIP, IID performs monthly water quality monitoring constituents of concern at 17 locations – incoming flow at All-American Canal Drop 4, and drainage water in nine river and seven drain sites throughout the water service area. IID reports the results to the Regional Board and provides flow data for 56 sites – incoming flow at AAC Mesa Lateral 5, and drainage flow for seven river and 48 drain sites throughout the Imperial Valley. IID also supplies the Regional Board with a list of current owners and tenants of agricultural land on a semi-annual basis.

Click here, to contact IID’s water quality section for more information.

DOWNLOAD / VIEW
IID Drain Water Quality Improvement Plan - Version 1.2 5/19/16 [PDF]
IID/ICFB Coalition Group Compliance Program - Board Presentation- Feb. 17, 2015 [PDF]
DWQIP Report Monitoring Sites [PDF]
New River Wetlands Project - Brochure [PDF]