Salinity Management: Salinity Management: Status of Regional Status of Regional Water Basins Water Basins The Wake- The Wake -up Call up Call � Prior to 2002 there were no TDS related Prior to 2002 there were no TDS related � impairments on the 303(d) List impairments on the 303(d) List � In 2002 11 waterbodies were added to the In 2002 11 waterbodies were added to the � 303(d) list for TDS related impairments 303(d) list for TDS related impairments 1
San Diego Regional 303(d) San Diego Regional 303(d) Workgroup Workgroup � Formed in reaction to the 2002 303(d) Formed in reaction to the 2002 303(d) � listing process as a workgroup of Project listing process as a workgroup of Project Clean Water Science and Technology Clean Water Science and Technology Technical Advisory Committee Technical Advisory Committee � Prepared an Analysis of Total Dissolved Prepared an Analysis of Total Dissolved � Solids in San Diego County and submitted Solids in San Diego County and submitted to SWRCB as part of the 2002 303(d) to SWRCB as part of the 2002 303(d) listing process listing process Basin Planning Issues Workgroup Basin Planning Issues Workgroup � Formed in 2003 to discuss the triennial Formed in 2003 to discuss the triennial � review of the San Diego Basin Plan review of the San Diego Basin Plan � Total Dissolved Solids Management Plan Total Dissolved Solids Management Plan � and the Development of Water Quality and the Development of Water Quality Objectives for Nutrients identified as Objectives for Nutrients identified as priority issues by stakeholders and priority issues by stakeholders and submitted as part of the triennial review submitted as part of the triennial review process process 2
More Recently More Recently � In 2006, another 27 waterbodies were In 2006, another 27 waterbodies were � added to the 303(d) list for TDS related added to the 303(d) list for TDS related impairments impairments � How many more will be added in the 2008 How many more will be added in the 2008 � update of the 303(d) list? update of the 303(d) list? Water Quality Standard for TDS Water Quality Standard for TDS in Surface Waters in Surface Waters � Established in 1975 when Basin Plan was Established in 1975 when Basin Plan was � adopted. adopted. � WQS = 500 mg/L applied to most WQS = 500 mg/L applied to most � subbasins within the San Diego Region. subbasins within the San Diego Region. � Protective of Municipal Drinking Water Protective of Municipal Drinking Water � and Agricultural Supply Beneficial Uses. and Agricultural Supply Beneficial Uses. 3
Total Dissolved Solids include: Total Dissolved Solids include: Carbonates/bicarbonates Carbonates/bicarbonates Chlorides Chlorides Sulfates Sulfates Phosphates Phosphates Nitrates Nitrates Magnesium Magnesium Sodium Sodium Iron and Iron and Manganese Manganese Rationale for Surface Water WQS Rationale for Surface Water WQS for TDS, Sulfate, Chloride, for TDS, Sulfate, Chloride, Manganese and Iron Manganese and Iron � Prevent taste problems in potable water Prevent taste problems in potable water � supplies supplies � Prevent leaf burn and salinity Prevent leaf burn and salinity- -related crop related crop � reductions reductions 4
Groundwater Water Quality Groundwater Water Quality Objectives Objectives � In most cases exceed surface WQOs In most cases exceed surface WQOs � � Not subject to the Federal Clean Water Not subject to the Federal Clean Water � Act, therefore much easier to change Act, therefore much easier to change TDS Concentrations in Stormwater TDS Concentrations in Stormwater Data from the Regional Stormwater Monitoring Program Wet Weather Mass Loading Stations 5
Estimated TDS Concentration Estimated TDS Concentration in Dry Season Flows in Dry Season Flows Watershed Observed Watershed Observed Average Average Range (mg/L) Range (mg/L) (mg/L) (mg/L) Santa Margarita 795 - - 1175 1175 965 Santa Margarita 795 965 San Luis Rey 952 - - 1945 1945 San Luis Rey 952 1395 1395 Carlsbad Carlsbad 905 - 905 - 6665 6665 2410 2410 San Dieguito San Dieguito 525 - 525 - 5020 5020 2380 2380 San Diego 665 - - 1845 1845 1350 San Diego 665 1350 Sweetwater 700 - - 3775 3775 Sweetwater 700 2175 2175 Tijuana Tijuana 380 - 380 - 1040 1040 600 600 2007 Data measured as conductivity and converted to TDS TDS in Groundwater TDS in Groundwater Watershed Observed Watershed Observed Concentrations (mg/L) Concentrations (mg/L) Santa Margarita Santa Margarita 600 - 600 - 1500 1500 San Luis Rey 500 - - 3400 3400 San Luis Rey 500 San Dieguito 1000 - - 1500 1500 San Dieguito 1000 San Diego 1000 - - 3000 3000 San Diego 1000 Sweetwater 300 - - 3100 3100 Sweetwater 300 Tijuana 500 - - 3000 3000 Tijuana 500 Data from San Diego County Water Authority Groundwater Report , June 1997 6
The Influence of Groundwater on The Influence of Groundwater on Surface Waters Surface Waters � Alluvial valleys contain unconfined Alluvial valleys contain unconfined � groundwater groundwater � Considerable interchange between surface Considerable interchange between surface � flow and groundwater flow flow and groundwater flow � Incompatibility between ground and surface Incompatibility between ground and surface � water quality objectives in Basin Plan water quality objectives in Basin Plan Influence of Surface Water Influence of Surface Water Hydrology Hydrology � Direct relationship between the magnitude if Direct relationship between the magnitude if � surface flow and mineral concentrations surface flow and mineral concentrations � When flows are low, poor When flows are low, poor- -quality surfacing quality surfacing � groundwater dominates. groundwater dominates. San Diego River San Diego River Mean Streamflow Mean Streamflow Streamflow Streamflow TDS Concentration TDS Concentration (CFS) (CFS) (mg/L) (mg/L) > 100 420 > 100 420 50 50 – – 100 100 610 610 20 20 - - 50 50 800 800 10 - - 20 20 960 10 960 0 - 0 - 10 10 1300 1300 7
Influence of Imported Water on Dry Influence of Imported Water on Dry Season Streamflow Season Streamflow When significant imported water deliveries began When significant imported water deliveries began there was a measurable increase in dry season flows there was a measurable increase in dry season flows San Luis Rey River at Oceanside Parameter Observed Flow (CFS) Parameter Observed Flow (CFS) 1930 - - 1967 1967 1968 - - 2000 2000 1930 1968 Mean Annual Flow 15.7 56.5 Mean Annual Flow 15.7 56.5 Median Monthly Flow 0.0 10.2 Median Monthly Flow 0.0 10.2 Mean Flow: June – Mean Flow: June –Oct. Oct. 0.3 0.3 14.2 14.2 Median Monthly Flow: June – Median Monthly Flow: June – Oct. Oct. 0.0 0.0 4.4 4.4 Imported Water Impacts Imported Water Impacts � In 2005, 89.9% of water supply imported In 2005, 89.9% of water supply imported � (573,048 acre- -feet) feet) (573,048 acre � Largest source of salt imported into San Largest source of salt imported into San � Diego Watershed Diego Watershed � Directly affects the salinity of recycled Directly affects the salinity of recycled � water water 8
Hodges Reservoir, February 2005 Reservoirs in the San Diego Region • 24 reservoirs, total storage capacity 571,000 acre feet • Most located in rural east County areas, but, increasingly at risk from residential and commercial development • San Diego’s reservoirs are part of the state-wide water supply system • watershed management = source water protection 1
City of San Diego Water Department Local Source Water System Sutherland Hodges Total Watershed Area San Vicente El Capitan 926 sq miles Miramar San Diego Murray Cottonwood Otay 2
Imported Sources 80-85% Local Sources 15-20% $ ~30% of total supply $ from local reservoirs $ Salinity in Drinking Water TDS, chloride, sulfate are secondary standards in drinking water • affects taste, odor, appearance • not a health effect at regulated levels constituent recommended (mg/L) upper (mg/L) TDS 500 1000 chloride 250 500 sulfate 250 500 Taste, odor, appearance are the #1 complaint / inquiry from water customers 3
Salinity in San Diego’s Drinking Water Sources • Imported sources –Colorado River ~ 700 mg/L –State Project ~ 300 mg/L –MWDSC blends sources to deliver water at <500 mg/L to San Diego • Local surface runoff impounded in reservoirs ~150 to 400 mg/L Basin Plan Standards and “Impairment” of Reservoirs • TDS Water Quality Objective at reservoirs – most reservoirs 500 mg/L – San Vicente & El Capitan 300 mg/L • 303(d) listing of reservoirs – 2002 Hodges – 2006 San Vicente, El Capitan, Murray, Miramar • “If you monitor, they will be listed.” 4
Basin Plan Standards and “Impairment” of Reservoirs • TDS listing of reservoirs dropped from final 2006 list (State Board overrode staff recommendations) Management of Salinity vs San Diego’s drinking water sources: a Paradox • local water agencies strive to deliver water of <500 mg/L • imported water +/- 500 mg/L • local reservoirs store imported water, but are influenced by local runoff • Where to focus efforts to manage salinity in drinking water reservoirs? 5
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