Groundwater: Making the Invisible - Visible In SoCal

 

Of course, depending on where you live in Southern California, your water comes from different places, the Colorado River, the Sacramento-San Joaquin Delta, Owens Valley and groundwater. SoCal’s water wholesaler is Metropolitan Water District (MWD). MWD imports water from the Colorado and the Sacramento-San Joaquin Delta, which it then sells to your local water agency.

 

Some of our cities are entirely dependent on imported water and others have no need, they have groundwater, and in the case of LADWP, groundwater is supplemented by water from the LA Aqueduct (Owens Valley & Mono Basin) and MWD.

 

 

You can find many definitions of groundwater – it is basically water stored underground through millennia via the process of snowmelt and rain seeping through the porous earth to an aquifer. Groundwater fills the spaces between, rocks, gravel and soil beneath the earth's surface. Groundwater is fairly pristine because of the process it undergoes to get into the aquifer. Alas, however with industrialization we have contaminated most of our groundwater sources.

 

Some of those contaminants occur naturally but most are man-made. E.g., landfills, pharmaceuticals and beauty products, industrial solvents, toxic chemicals, motor oils, nitrates (fertilizers & pesticides), PFAS/PFOA/PFOS compounds used in fire-proofing products, human waste, other hazardous waste - many in storage tanks, fracking, microplastics, tire dust, road salts, depletion and overdraft leading to salt water intrusion.

 

Drinking contaminated water can have lasting and deadly health effects. Think Erin Brockovich (the movie). Diseases such as cancer, hepatitis, dysentery, eczema, dermatitis psoriasis and poisoning. Wildlife, flora and fauna are also affected as the contaminated water moves into our food chain.

 

Groundwater depletion or over-drafting is primarily caused by the over-pumping of groundwater from the aquifer. This leads to land subsidence (surface land falls/drops), lowering of the water table, increased costs as you have to drill further and further underground to reach water, then pump it back up to the surface. This also reduces water surface supplies – groundwater and surface water are connected, you reduce one, then you reduce the other. Last but not least as mentioned earlier

salt-water intrusion in coastal areas, salt water moves into the space left behind by the overdraft of the aquifer.

 

 

Luckily for us, there are many solutions today that involve fast moving technology to help in the clean up (remediation) and replenishment of our groundwater sources. Granulated activated carbon, high pressure membranes, ion exchange resins, reverse osmosis, UV light treatment, air stripping, pump-and-treat, surfactant/cosolvent flushing, air sparging, permeable reactive barrier and bioremediation are some of the technologies used today.

 

One of the other things that SoCal has done so very well is groundwater replenishment, through spreading grounds and injection wells using recycled water. Orange County has the world renowned and world’s largest Groundwater Replenishment System (GWRS) and Los Angeles County, not to be outdone, has the Water Replenishment District (WRD). They both have lessoned our dependence on imported water, but of course we can do more, starting with conservation, stormwater capture and implementing more nature based solutions.

 

Orange County can and should implement stormwater capture projects; they already have a great Environmental Cleanup Program funded by Measure M which protects our waterways from vehicle-generated pollution on freeways and streets. How wonderful if they combined a Green Streets Program like LA Sanitation has in LA and/or a program similar to LA County’s Safe Clean Water Program.