Attachment A

To

Resolution No. R5-2010-0046

Basin Plan Amendments

The Water Quality Control Plan for t he Sacramento River and San Joaquin River Basins is amended as presented below. Dele tions are indicated as strikethrough text (deleted text ) and shaded fields (deleted field). Additions are shown as underlined text (added text ). Italicized text ( notation text ) is included to locate

where the modifications will be made in t he Basin Plan. All other text changes are shown accurately, however, formatting on the page may change.

Under the Chapter IV heading: “Regional Water Board Prohibitions, Item 6 on page IV-26.00, make the following changes:

b. The discharge of agricultural subs urface drainage water to Salt Slough and wetland water supply channels ident ified in Appendix 40 is prohibited after 10 January 1997, unless water qua lity objectives for selenium are being met. This prohibition may be re considered if public or private interests prevent the implementation of a separate conveyance facility for agricu ltural subsurface drainage.

c. The discharge of agricultural subs urface drainage water to Mud Slough (north) and the San Joaquin River from Sack Dam to the mouth of the

Merced River Mud Slough (north) is prohibited after 1 October 2010 unless water quality objectives for sel enium are being met. The discharge of agricultural subsurface drainage water to Mud Slough (north) and the San Joaquin River from the Mud Slough confluence to the Merced River is prohibited after 31 December 2019 unl ess water quality objectives for selenium are being met. This prohibition may be reconsidered if public or private interests prevent the implem entation of a separate conveyance facility for agricultural subsurface drainage to the San Joaquin River. The prohibition becomes effective immedi ately upon Board determination that timely and adequate mitigation, as outlined in the 2010-2019 Agreement

for Continued Use of the San Luis Drain 1 has not been provided.

Under the Chapter IV heading: “Agricul tural Drainage Discharges in the San Joaquin River Basin” page IV-31.00, make the following changes:

Per the amendment to the Basin Plan for San Joaquin River subsurface agricultural drainage, approved by the St ate Water Board in Resolution No.

1 United States Department of the Interior, Bu reau of Reclamation, Central Valley Project,

California and San Luis & Delta-Mendot a Water Authority, Los Banos, CA, Agreement for Continued Use of the San Luis Drain for the per iod January 1 2010, through December 31, 2019.Attachment A to -2-

Resolution No. R5-2010-0046

96-078, as amended by Resolution No. R5-2010-0046 and incorporated herein, the following actions will be implemented.

1. In developing control actions for se lenium, the Regional Board will utilize a priority system which focuses on a combi nation of sensitivit y of the beneficial

use to selenium and the environmental benefit expected from the action.

2. Control actions which result in seleni um load reduction are most effective in meeting water quality objectives.

3. With the uncertainty in the effe ctiveness of each control action, the regulatory program will be conducted as a series of short-term actions that are designed to meet long-te rm water quality objectives.

4. Best management practices, such as water conservation measures, are applicable to the control of agr icultural subsurface drainage.

5. Performance goals will be used to measure progress toward achievement of water quality objectives for seleni um. Prohibitions of discharge and waste discharge requirements will be used to control agricultural subsurface drainage discharges containing sele nium. Compliance with performance goals and water quality objectives for nonpoint sources will occur no later than the dates specified in Table IV-4 for Mud Slough (north) and the San Joaquin River from the Mud Slough confluence to the Merced River.

6. Waste discharge requirements will be used to control agricultural subsurface drainage discharges containing selenium and may be used to control discharges containing other toxic trace elements.

7. Selenium load reduction requirem ents will be incorporated into waste discharge requirements as effluent limit s as necessary to ensure that the selenium water quality objectives in t he San Joaquin River downstream of the Merced River inflow is achieved. The Board intends to implement adopted a TMDL for selenium in the San Joaquin River in 2001 after public review.

---Additional changes are shown on the next page---Attachment A to -3-

Resolution No. R5-2010-0046

Table IV-4. Compliance Time Schedule for Meeting the 4-day Average and Monthly Mean Water Quality Objective for Selenium

Selenium Water Quality Objectives (in bo ld) and Performance Goals (in italics)

1 The water year classification will be established using the best available estimate of the 60

- 20

- 20 San

Joaquin Valley water year hydrologic classification (as defined in Footnote 17 for Table 3 in the State

Water Resources Control Board’s Water Quality Control Plan for the San Francisco Bay/S acramento

- San

Joaquin Delta Estuary , May 1995) at the 75% exceedance level using data from the Department of Water

Resources Bulletin 120 series. The previous water year’s classification will apply until an estimate is made

of the current water year. Water Body/Water Year Type 1 1 Oct o ber

1996 1 October

2002 1 October

2005 1 October

2010 31

December

2015 31

December

2019 Salt Slough and

Wetland Water Supply Cha n nels

listed in Appendix 40 2 u g/ L monthly

mean

San Joaquin

River below the
Merced River;

Above Normal

and Wet Water Year types 1 5 u g/L monthly

mean 5 u g/L

4

- day

avg.

San Joaquin

River below the
Merced River; Critical, Dry,

and Below

Normal Water Year types 8 u g/L monthly

me an 5 u g/L monthly

mean 5 u g/L

4

- day

avg.

Mud Slough (north) and the San Joaquin

River from Sack

Dam the Mud Slough

confluence to the

Merced River 5 u g/L

4

- day

avg. 15 ug/L monthly

mean 5 ug/L 4-day

avg.