Southern California Water Issues

Groundwater

What is Groundwater?  Water found in the pores and fractures of soil and bedrock  Largest reservoir of fresh water  Tends to be less polluted than surface water

What is Groundwater?  An important erosional agent –Groundwater is often mildly acidic –Contains weak carbonic acid –Forms caverns at or just below the zone of saturation –Karst topography on the surface

Groundwater Terminology  Belt of soil moisture  Zone of saturation  Zone of aeration  Capillary fringe  Water table

Groundwater Terminology  Water table –The upper limit of the zone of saturation –Depth is highly variable –Varies seasonably and from year to year –Shape is usually a subdued replica of the surface topography

Groundwater Terminology  How does water get from the stream to the water table? –Gaining streams – gain water from the inflow of groundwater through the streambed –Losing streams – lose water to the groundwater system by outflow through the streambed –Interactions - A combination of the first two

Groundwater Movement & Storage  Porosity –Percentage of total volume of rock or sediment that consists of pore spaces  Permeability –The ability of a material to transmit a fluid

Groundwater Movement & Storage  Specific retention –The portion whish is retained as a film on particles, rock surfaces, and pore spaces  Specific yield –The portion which will drain under gravity  In general, –Porosity = Specific retention + Specific yield

Groundwater Movement & Storage  Aquifer –A zone of Earth material capable of supplying groundwater at a useful rate from a well  Aquitard –A zone of Earth material that holds water but cannot transmit it fast enough to pump from a well

Getting Groundwater Out of the Ground  “Natural” Methods –Springs, Hot Springs, & Geysers

Getting Groundwater Out of the Ground  Man-made Methods –Wells

Problems with groundwater removal  Non-renewable resource / Groundwater Recharge  Ecological Damage  Subsidence  Contamination

Problems with groundwater removal  Non-renewable resource / Groundwater Recharge –Can take centuries to occur –Hindrances:  Paved river channels  Urbanization

Ecological Damage

Problems with groundwater removal  Subsidence –Over pumping of groundwater –Water removed from pore spaces –Air filled pores collapse –Grains pack together more tightly –Ground subsides

Problems with groundwater removal  Sources of Contamination –Natural Sources  Seawater Intrusion  Biologic activity / organisms –Bacteria and viruses  Naturally occurring elements –Uranium, radium, arsenic, and fluoride

Seawater Intrusion

Problems with groundwater removal  Sources of Contamination –Human Caused  Acid Rain –Acid rain is caused by:  CO 2 from cars and power plants  NO x from cars  SO 2 from power plants

Problems with groundwater removal  Sources of Contamination –Human Caused  Agricultural / Industrial Run-off Leakage from waste disposal, treatment, or storage sites. Leakage from waste disposal, treatment, or storage sites. Discharges from factories, industrial sites, or sewage treatment facilities. Discharges from factories, industrial sites, or sewage treatment facilities. Leaching from pesticides and fertilizers on yards or fields. Leaching from pesticides and fertilizers on yards or fields. Accidental chemical spills. Accidental chemical spills. Leakage from underground storage tanks. Leakage from underground storage tanks. Improper disposal of household wastes such as cleaning fluids, paint, and motor oil Improper disposal of household wastes such as cleaning fluids, paint, and motor oil

Groundwater In Southern California  Geological Setting –S. California is broken into fault blocks of different elevation –Sediment deposited on the lower blocks forms the aquifers

Groundwater In Southern California  Coastal Plain –These areas are formed by alluvial deposits of the LA, San Gabriel, and Santa Ana Rivers –Unconfined aquifers lie just beyond the narrows

Los Angeles County, California Hydrologic Unit Code Latitude 34°05'35", Longitude 117°57'35" NAD27 Gage datum 387 feet above sea level NGVD29 The depth of the well is feet below land surface. The depth of the hole is 200 feet below land surface.

Groundwater In Southern California  Inland Valleys –Water here drains in the subsurface through the narrows to the coastal plain –San Fernando Valley  Has extensively used groundwater for agriculture and domestic needs  Now polluted with TCE - a Superfund site  Has also used Owens Valley water since 1915

Groundwater In Southern California –San Gabriel Valley  Groundwater is heavily used  Basin has the storage capacity of 10 million acre feet  The San Gabriel Basin is polluted with cancer causing chemicals –trichloroethylene (TCE) –perchloroethylene (PCE) –carbon tetrachloride (CTC)

Groundwater In Southern California –San Gabriel Valley (continued)  San Gabriel Valley became a Superfund site in 1985  More than 1 million people rely on the San Gabriel aquifer for drinking water.

Sea Water Intrusion  This is a worldwide problem –First recognized here at Redondo Beach in 1912 –LA County Department of Public Works is responsible for prevention

Sea Water Intrusion  The Barrier Projects –West Coast Basin Barrier Project  10 miles from El Segundo to Palos Verdes –Dominguez Gap Barrier  6 miles from San Pedro to Long Beach –Alamitos Barrier Project  7 miles from Long Beach to Seal Beach

Methods Of Augmenting Local Water Supplies  Water Importation by Aqueducts  Water Reclamation  Desalination  Icebergs

History Of Aqueducts In California

 Owens Valley Aqueduct

History Of Aqueducts In California  Owens Valley Aqueduct –Concept resulted from the drought of which threatened the growth of LA –Conceived by Fred Eaton and William Mulholland –US Reclamation Service interested in area for irrigation purposes J.B. Lippincott, Fred Eaton and William Mulholland. This photograph appeared in the Los Angeles Times, August 6, 1906.

History Of Aqueducts In California  Owens Valley Aqueduct –1904 – LA agents secretly buy options on land with water rights –1905 – Preliminary bond measure approved –1906 – Congress grants aqueduct right of way over federal land with strong backing from President Theodore Roosevelt –1907 – Full bond measure for $25M approved

History Of Aqueducts In California  Owens Valley Aqueduct –1913 – Construction of aqueduct completed –1915 – San Fernando Valley annexed into LA –1924 – Owens Lake and ~50 miles of the Owens River are dry –1930 – 95% of Owens Valley farmland owned by Los Angeles; $40M bond issue approved to expand aqueduct into Mono Basin –1940 – Extension completed, diversions begun

History Of Aqueducts In California  Owens Valley Aqueduct –1963 – plans for a second aqueduct approved –1970 – DWP plans to fill new aqueduct by:  Reducing irrigation water  Diverting surface water from Inyo and Mono counties  Pumping groundwater –1972  Inyo county successfully sued to stop groundwater pumping increase  Wetland meadows, seeps, springs, and marshes dried and disappeared, well water levels dropped, and vegetation in the valley began to change.

History of Aqueducts in California  Owens Valley Aqueduct –Opposition to the aqueduct  Began in Owens Valley with the first land acquisitions in 1905  Still controversial today

History of Aqueducts in California  Colorado River Aqueduct –Droughts from the mid-1920's to early 1930's resulted in 500,000 people of LA approving a $220 million bond issue in 1931 for a new aqueduct

History of Aqueducts in California  Colorado River Aqueduct –The MWD (128 cities, 12 million people) built the Colorado River Aqueduct  Extends 242 miles from Lake Havasu behind Parker Dam  4 pumping stations  Supplied 1.2 million acre-ft/year to S. California for many years  Now reduced to 550,000 acre-ft/year  Supplies 6% of LA's needs  Supplies East LA, the Harbor & part of the central city

History of Aqueducts in California  California Aqueduct –2.5 million people of LA approved a $1.75 billion water project –Aqueduct stretches 444 miles from Oroville Dam –Deliveries began in 1971

History of Aqueducts in California  Future Aqueducts are unlikely –Belief that more water means more people and more pollution –Water rationing first occurred in LA on July 1, 1977

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