| Water Body Name: | Winters Canal (Yolo County) |
| Water Body ID: | CAR5112000020080801150313 |
| Water Body Type: | River & Stream |
DECISION ID |
93954 |
Region 5 |
Winters Canal (Yolo County) |
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| Pollutant: | Diazinon |
| Final Listing Decision: | Do Not Delist from 303(d) list (being addressed with action other than TMDL) |
| Last Listing Cycle's Final Listing Decision: | Do Not Delist from 303(d) list (being addressed with action other than TMDL)(2016) |
| Revision Status | Original |
| Sources: | Agriculture |
| Expected Attainment Date: | 2026 |
| Implementation Action Other than TMDL: | This water body segment-pollutant combination is being addressed through Basin Plan requirements established under CRWQCB-CVR resolution R5-20140041, and implemented through Board established Waste Discharge Requirements for agricultural discharges. The sources of diazinon to this segment have been identified as offsite movement of diazinon from diazinon applications by the agricultural dischargers regulated by the CRWQCB-CVR WDRs. The Basin Plan identifies numeric water quality objectives for diazinon and chlorpyrifos. The Basin Plan and WDRs require growers to implement management practices through the development and implementation of water quality management plans to meet water quality objectives for diazinon as soon as possible but no longer than ten years from the date of approval of the Basin Plan Amendment. These management plans are required to be developed and implemented within one year of the Basin Plan Amendment approval. Agricultural management practices to be implemented may include pest management practices, pesticide application practices, vegetation management practices and water management practices, all of which are effective in reducing offsite movement of diazinon into surface water. The Basin Plan and the Monitoring and Reporting programs in the WDRs require monitoring to determine if adequate reductions are being attained. The Basin Plan and WDRs require management practices to be iteratively improved through updates of the management plans until the water quality objectives are achieved. |
| Impairment from Pollutant or Pollution: | Pollutant |
| Regional Board Conclusion: | This water body - pollutant combination is being considered for removal from the 303(d) list under sections 2.2 and 4.11 of the Listing Policy. No new data or information was available for the 2014 cycle. Under section 4.11, a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. The evidence indicates that diazinon concentrations are not attaining the applicable water quality standards, but existing pollution control requirements, under State authority, are stringent enough to implement applicable water quality standards because the impairment is being addressed by an enforceable regulatory program, other than a TMDL, that is reasonably expected to result in attainment of the water quality standards within a reasonable, specified time frame.
This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfy the data quantity requirements of section 6.1.5 of the Policy. 3. Three of 3 available calculated 4-day average diazinon concentrations exceeded the 4-day average diazinon criterion. These exceedances occurred more than once every three years. 4. One of 9 available 1-hour average diazinon concentrations exceeded the 1-hour average diazinon criterion. This exceedance did not occur more than once every three years. 5. The sources of diazinon to this water body segment have been identified as offsite movement of diazinon from diazinon applications by the agricultural dischargers, who are regulated under enforceable Waste Discharge Requirements (WDRs). 6. In 2016, the Board adopted Resolution R5-2014-0041 establishing Basin Plan amendments that primarily address the regulation of agricultural pesticide runoff and discharges of diazinon and chlorpyrifos in the Central Valley which are implemented through Board established Waste Discharge Requirements for agricultural dischargers. The amendments established numeric water quality objectives for diazinon and a control program to ensure that the objectives will be attained within a reasonable, specified time frame. The Basin Plan and WDRs require growers to implement management practices through the development and implementation of water quality management plans to meet water quality objectives for diazinon as soon as possible but no longer than ten years from the date of approval of the Basin Plan Amendment. These management plans are required to be developed and implemented within one year of the Basin Plan Amendment approval. 7. Agricultural management practices to be implemented may include pest management practices, pesticide application practices, vegetation management practices and water management practices, all of which are effective in reducing offsite movement of diazinon into surface water. 8. The Basin Plan and the Monitoring and Reporting programs in the Boards WDRs require monitoring to determine if adequate reductions are being attained. The Basin Plan and WDRs require management practices to be iteratively improved through updates of the management plans until the water quality objectives are attained. 9. Pursuant to section 4.11 of the Listing Policy, no additional data and information are available indicating that standards are being met. |
| Regional Board Decision Recommendation: | After review of the available data and information described in the lines of evidence associated with this decision, the Regional Water Board determined that this water body and pollutant combination is still impaired and that it should be listed as being addressed by another regulatory program that is reasonably expected to result in attainment of the water quality standard within a reasonable, specified time frame because an alternative State regulatory program is in place which can be reasonably expected to result in attainment of the water quality standard within a reasonable, specified time frame. |
| State Board Review of Regional Board Conclusion and Recommendation: | The Basin Plan and WDRs require growers to implement management practices through the development and implementation of water quality management plans to meet water quality objectives for diazinon as soon as possible but no longer than ten years from the date of approval of the Basin Plan Amendment. These management plans are required to be developed and implemented within one year of the Basin Plan Amendment approval.
7. Agricultural management practices to be implemented may include pest management practices, pesticide application practices, vegetation management practices and water management practices, all of which are effective in reducing offsite movement of diazinon into surface water. 8. The Basin Plan and the Monitoring and Reporting programs in the Boards WDRs require monitoring to determine if adequate reductions are being attained. The Basin Plan and WDRs require management practices to be iteratively improved through updates of the management plans until the water quality objectives are attained. 9. Pursuant to section 4.11 of the Listing Policy, no additional data and information are available indicating that standards are being met. |
| State Board Decision Recommendation: | After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board. |
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| LOE ID: | 23290 | ||||
| Pollutant: | Diazinon | ||||
| LOE Subgroup: | Pollutant-Water | ||||
| Matrix: | Water | ||||
| Fraction: | Total | ||||
| Beneficial Use: | Warm Freshwater Habitat | ||||
| Aquatic Life Use: | Warm Freshwater Habitat | ||||
| Number of Samples: | 3 | ||||
| Number of Exceedances: | 3 | ||||
| Data and Information Type: | PHYSICAL/CHEMICAL MONITORING | ||||
| Data Used to Assess Water Quality: | Nine water samples were collected from Winters Canal in 2005, representing three calculated 4-day average diazinon concentrations and nine 1-hour average diazinon concentrations. Three of the three available calculated 4-day average diazinon concentrations exceeded the 4-day average diazinon criterion of 0.100 ug/L. One of the nine available 1-hour average diazinon concentrations exceeded the 1-hour average diazinon criterion of 0.160 ug/L. | ||||
| Data Reference: | Revised Draft of the 2007 Review of the Monitoring Data for the Irrigated Lands Regulatory Conditional Waiver Program | ||||
| Monitoring and Reporting Program, Order Nos. R5-2003-0826, R5-2005-0833, and R5-2008-0005 for Coalition Groups Under Resolution No. R5-2003-0105, Conditional Waiver of Waste Discharge Requirements for Discharges From Irrigated Lands Within the Central Valley Region | |||||
| SWAMP Data: | Non-SWAMP | ||||
| Water Quality Objective/Criterion: | No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses. All waters shall be maintained free of toxic substances in concentrations that produce detrimental physiological responses in human, plant, animal, or aquatic life. | ||||
| Objective/Criterion Reference: | Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed | ||||
| Objective/Criterion Reference: | Water quality criteria for diazinon and chlorpyrifos. Administrative Report 00-3. Rancho Cordova, CA: Pesticide Investigations Unit, Office of Spills and Response. CA Department of Fish and Game | ||||
| Evaluation Guideline: | California Department of Fish and Game Hazard Assessment Diazinon Criteria: 0.160 ug/L as a 1-hour average diazinon concentration, and 0.100 ug/L as a 4-day average diazinon concentration, not to be exceeded more than once every three years. | ||||
| Guideline Reference: | Water quality criteria for diazinon and chlorpyrifos. Administrative Report 00-3. Rancho Cordova, CA: Pesticide Investigations Unit, Office of Spills and Response. CA Department of Fish and Game | ||||
| Spatial Representation: | Samples were collected from Winters Canal at Road 86A. | ||||
| Temporal Representation: | Samples were collected daily from January 26 to 31, 2005, and on February 3, 16, 17, and 18, 2005. | ||||
| Environmental Conditions: | |||||
| QAPP Information: | Data quality: Good. Monitoring was conducted in accordance with Central Valley Water Board Monitoring and Reporting Program (order number R5-2003-0826) requirements (CVRWQCB, 2003) | ||||
| QAPP Information Reference(s): | |||||