Salinity ManagementProject

Santa Ana Region

Gerard Thibeault

Executive Officer

January 26, 2007

State of California

Water Quality Control Regions

1

5

6

2

3

478

9

1. North Coast

2. San Francisco

Bay

3. Central Coast

4. Los Angeles

5. Central Valley

6. Lahontan

7. Colorado River

8. Santa Ana

9. San Diego

Need for UpdatedSalt Management Plan

• Discharger Concerns

– TDS Limitations

– Objectives – 1972

• Rushed, under funded• Not based on good science

• No good data on assimilative capacity

• If 1972 objectives invalid

– Potential for enormous unnecessary expenditures of public funds

Genesis of Salt Management Plan

• Dischargers and water agencies appealed to Regional Board for complete review of salt management plan

• Regional Board agreed to evaluate objectives

– Two-edged sword

Develop procedures to calculate groundwater quality

objectives

– 1972 Basin Plan Objectives:

• Significantly under-funded effort• TDS: About 200 wells; Two years of

data• Nitrate objectives not scientifically

calculated

– TIN/TDS Study:

• TDS/Nitrate: About 1,800 wells; 20 years of data

• Nitrate and TDS objectives rigorously calculated

Santa Ana BasinSalt Management Plan

• N/TDS Task Force – 7 years, water supply agencies (upper and lower basins), wastewater dischargers, USGS, Watermaster

• Funded by Task Force members

– Approx. $3.5 million

Basin Plan AmendmentBottom Line

• 90 page staff report

• 99 page basin plan amendment

• Numerous public workshops and hearings

• Complete assessment and adoption of new objectives and boundaries throughout Region

• Adopted by Reg Bd, State Bd, and OAL WITHOUT dissent or opposition

N/TDS Task Force

• All factions within the basin represented

– Upper Basin v. Orange County

– Water Supply Agencies v. WW dischargers

• Consensus-building process

• Establish ground rules

• Strict conformance with existing laws and federal and state policies

N/TDS Task Force

• Complete scientific review of historic and current ambient water quality

• 20-Year running averages

• All wells in region with 3 or more data points and quality control

• Thousands of data points

• Developed nitrogen, TDS and water level maps for every 2 years since 1950 for entire region

N/TDS Task Force

• Hydrogeotechnical review of all groundwater basin boundaries

• All boundaries digitized

• Mass-weighted analysis of historic and current ambient groundwater quality

N/TDS Task Force

• Re-created objectives using 1972 20-year running average and evaluated current ambient quality, also with 20-year average

• Strong scientific basis in conformance with laws and policies

• Established antidegradation objectives (St. Bd. Res. 68-16)

• Compared current ambient quality to objectives to determine whether assimilative capacity exists

Develop Queries to Extract Data

• QA/QC Checks• Develop TDS and NO3-N time histories• Appropriate statistical tests for

normality and outliers» Shapiro-Wilk test

• Standard methods tests» Anion-cation balance» Measured TDS vs. calculated TDS» Measured EC and ion sums» TDS to EC ratios

• Reject data if any test failed

TDS and NO3-N Concentration Time Series

0

100

200

300

400

500

600

1954 1969 1984 1999

Year

TD

S C

on

cen

trat

ion

(m

g/L

)

0

5

10

15

20

25

30

NO

3-N

Co

nce

ntr

atio

n (

mg

/L)

TDSNew TDSADFMNO3-NNew NO3-N1000186 WE ID:

Local Name: PL 25A

Owner Name: EAST VALLEY WATER DISTRICT

Develop WQ Point Statistics at Each Well

• Each well must have at least three data points in separate years during the analysis period.

• TDS and Nitrate-nitrogen

• Computed statistics account for variability resulting from:

• sampling error• analytical error• hydrological/climatic events• non-homogeneous hydrogeologic properties

Develop procedures to calculate groundwater quality

objectives

• Develop volume-weighted management zone estimates of TDS and nitrate concentrations

• ConcentrationMZ = MassMZ / GW VolumeMZ

• historical ambient conditions (1954 – 1973)– Objective setting period

• current ambient conditions (1978 – 1997)– Measure of compliance

Compute Ambient Water Quality for Management

Zones

• Create 400x400m grid across all MZs

• Populate each grid cell with:• Water quality (TDS and Nitrate)• Groundwater elevations• Specific yield• Bottom of the aquifer• Aquifer geometry (layering) where

appropriate

Compute Ambient Water Quality for Management Zones

• Create 3-D GIS layers of:• Water quality (TDS and Nitrate)• Groundwater elevations• Specific yield• Bottom of the aquifer• Aquifer geometry (layering) where

appropriate

• 3rd dimension is value of layer

Bo tto m o fA quifer

G rid C ell Pro perties:Specific yield ,co ncentratio n

W aterL evel

C am b = 1 /V T * S(V i * c i)

View Sample Map

Assimilative Capacity

• If assimilative capacity exists, then may discharge at quality in excess of objectives, if supported by antidegradation analysis (maximum benefit & support beneficial uses)

– This reduces or exhausts assimilative capacity

• If no assimilative capacity, may not discharge at quality above objectives (Rancho Caballero decision)

Implications of the TIN/TDS Study

• Management Zones that lack assimilative capacity must have TDS and N03 discharge concentrations limited to a level at or below the proposed objectives.

• Effects:• Planned recycled water recharge projects• Potentially direct recycled water re-use• Surface discharge in reaches that have GWR

beneficial uses

Max Ben Objectives

• Less stringent objectives would allow lowering of water quality, so must satisfy state’s antidegradation policy – Resolution 68-16

– 1. Demonstrate that beneficial uses will continue to be protected

– 2. Water quality consistent with maximum benefit to the people of the state will be maintained

What are the Causes of TDS and N Degradation in the Chino

Basin?

• Returns from use from agriculture and urban water users

• Recharge

Figure 3Comparison of TDS Concentration Time Histories for

Selected Water Resources Management Cases

300

320

340

360

380

400

420

440

460

480

500

2000 2010 2020 2030 2040 2050 2060 2070 2080 2090 2100

TDS

Con

cent

ratio

n (m

g/L)

Case 1

Case 2

Case 3

Case 4

Max Ben Demonstration

• Chino Basin Example

– Integrated water supply plan

• Recycled water• Enhanced stormwater capture• Two (later, three) desalters• Recharge excess low-TDS SPW• Hydraulic Isolation• Extensive monitoring proposal• Water softener elimination program

Chino Basin Max Ben

• Max benefit to people of state

– Extraction and treatment of salt-contaminated groundwater

– Protect downstream users from rising poor-quality groundwater

– Less reliance on SPW for growth

– Integrated water supply planning – Optimum Basin Management Program

Status of Basin Plan Amendment

• Approved by:• RWQCB – January 2004• SWRCB – September 2004• OAL – December 2004

• No negative comments through adoption process

• All documents posted on web site

• www.waterboards.ca.gov/santaana