Developing Local Resources for Groundwater Replenishment

Transcription

1 Developing Local Resources for Groundwater Replenishment

2 Local Groundwater Supply Central and West Coast Basins Santa Monica Mtns Over 10% 4 Area of Million California s 43 = Cities 420 People mi 2 population > 400 Water Wells Merced Hills Pumping 250,000 acre feet San Gabriel Valley Los Angeles Los Angeles River San Gabriel Mtns Puente Hills Coyote Hills San Gabriel River Long Beach Palos Verdes Hills Pacific Ocean

3 Water Wells over 400 active wells

4 In our region Groundwater provides 40% of total water demand.

5 Groundwater Elevation (feet from sea level) Groundwater Elevation (feet from sea level) 20 West Basin Key Well 3S/14W-22L s-1950s OVERDRAFT Central Basin Key Well 2S/13W-10A Plunging Water Levels Loss of Groundwater Supply Wells going Dry Seawater Intrusion

6 Solutions 1) Court adjudicated (capped) groundwater pumping to 92 billion gallons per year (281,835 acre feet per year). 2) LA County Flood Control District installed 16 miles of injection wells along the coast to pump in freshwater and stop the seawater intrusion. Natural groundwater wasn t enough to meet demand 3) WRD formed in 1959 to replenish aquifers and protect groundwater quality.

7 Los Angeles Surface Recharge Whittier West Inglewood Central Coast Torrance Coastal Injection Basin Long Beach Basin Orange County 5 miles 5 km

8 Rio Hondo spreading grounds San Gabriel spreading grounds

9 Acre Feet Central Basin Replenishment Sources 130, , , ,000 90,000 80,000 70,000 60,000 50,000 40,000 30,000 20,000 10,000 - Imported Water 21,000 Recycled Water 50,000 Stormwater 54,000

10 Feb-30 Feb-40 Feb-50 Feb-60 Feb-70 Jan-80 Jan-90 Jan-00 Water Surface Elevation (feet MSL) Feb-30 Feb-40 Feb-50 Feb-60 Feb-70 Jan-80 Jan-90 Jan-00 Water Surface Elevation (feet MSL) WEST COAST BASIN KEY WELL Results of WRD basin management CENTRAL BASIN KEY WELL Date Rising water levels & drought protection

11 Cost per Acre Foot Local reliable supply Drought protection Cost effective Benefits of Groundwater $700 $600 $500 $400 $300 $200 $100 $- Imported Water Groundwater

12 Historical Cost of Groundwater compared to Imported Water (cost per Acre Foot) $800 $700 $600 $500 $400 $300 $200 $100 $0 Imported Water WRD RA Slide 12

13 Current Imported Water Demands Montebello Forebay Spreading Grounds 21,000 AFY (out of 125,000 AFY) West Coast Barrier 3,400 AFY (out of 15,000 AFY) Alamitos Gap Barrier 3,000 AFY (out of 6,000 AFY) Dominguez Gap Barrier 6,000 AFY (out of 9,000 AFY)

14 Acre Feet WRD s WIN Program will reduce or eliminate need for imported water to replenish groundwater 200, , ,000 50,000 - Past Current Future Imported Recycled Stormwater

15 Collection of projects to eliminate WRD demand for imported water Projects to: Capture and conserve additional stormwater Increase use of recycled water for groundwater replenishment Creates locally self-sufficient groundwater supply for 10% of population of California (4 million residents in the Central and West Coast basins)

16 Stormwater Projects under WIN Program

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18 Dam up the river (temporarily) Inflatable rubber dams are proven technology to halt river flow and promote infiltration. 2 new dams in 2008 in San Gabriel River. Joint project between WRD/LADPW. Provide 3,600 afy more storm water capture and infiltration.

19 Increase Conservation Pool behind the Whittier Narrows Dam WND is flood control project built by Army Corps Oil wells behind dam limited water storage capability (conservation pool). WRD/LADPW cooperated to remove oil wells. Conservation pool increased allowing 1,500 afy more storm water capture. Can increase by another 1,000 afy with additional study

20 Interconnection Pipeline Two-way pipeline (78 diam, 1.2 mi) to divert flows between Rio Hondo and San Gabriel. WRD/LACDPW project will go online March Will increase storm water capture by 1,300 afy, also more recharge flexibility.

21 Increase Vadose Zone Shallow water table limits storm water recharge. Concept to install pumping wells to drawdown water table, exposing more vadose zone, and freeing up more room for storm water capture / recharge. Modeling shows 17,000 afy more storm water can be captured.

22 Low Impact Developments (LIDS) Set of approaches to reduce runoff and pollutants from reaching surface waterways, and promote recharge. Bioswales Porous Pavement Dry wells Rain Harvesting Elmer Avenue site, LA and SG Rivers Watershed Council Smart Landscaping

23 Robb Whitaker