How Does California Better Capture Precious Storm Water?

Vern Scott
9 min readFeb 6, 2023


Recent storms right after historic drought have exposed California’s “feast or famine” problem, either too much or not enough water. In an era when large dams have become unfashionable (mostly due to expense and wildlife issues), groundwater recharging has been suggested. As this may have limitations, I’m going to suggest community storm water reservoirs/cisterns, and conveyances able to ship stormwater south.

Though helped by the ‘23-’24 storms, Lake Meade behind Hoover Dam is still dangerously low. Less dependence on Lake Meade from the LA basin via additional Northern California storm water delivery would help.

THE STORMWATER STORAGE PROBLEM: After years of being parched by drought, Californians (and especially farmers) have suffered water shortages and have been compelled to pump groundwater aquifers half-dry. But then the storms came, which refilled many of the Northern California reservoirs, but left much of the Colorado River Basin (which helps serve LA, Las Vegas and Phoenix, among others) relatively dry. Meanwhile, dams (which were designed to hold large amounts of stormwater, minimize flooding, and produce hydroelectric power) have received a black eye, mostly because they may harm wildlife habitat and eventually silt up. Before those in the rest of the Country say “let California dry up as it’s God’s punishment”, remember that the rest of you get much of your food from places like California and Arizona. Also, it should be noted that we already do capture and redirect much storm water, in a series of dams and reservoirs built during the last century. There are those also that claim that storm surcharges are a necessary “cleansing” of rivers and bays, but I’ll assume that there’s a happy medium here.


1) COMMUNITY STORM BASINS: In the olden days, there were marshes which stored floodwaters, but many were drained for development. Since realizing this mistake, community storm basins have been built in California and elsewhere. You will see them as ballparks and wildlife wetlands, which are wet for a few months in Winter, then dry thereafter. They are built primarily to prevent flooding, but also provide recreational space and habitat. The water that fills these basins generally leaches into the soils or evaporates, but could easily be used as irrigation water (or even domestic water, if treated).

2) RURAL STORM BASINS: A rural stormwater basin might be an area of seasonal ag usage, which is used as storm water detention in the Winter. A good example of this would be the Yolo and Sutter bypasses (which carries Sacramento River flood water to low-lying agricultural areas in the Sacramento Valley), built in stages after devastating historic floods (which flooded Yuba City and others). A system of weirs, pumps and levees were built to redirect water from the Sacramento River to farmland. Once again, this flood water generally leaches or evaporates, but could be stored as future irrigation water. Another large set of diversions are the Delta Mendota and California Aqueduct Canals (which divert water from the San Joaquin Delta south to the Fresno and Bakersfield areas for farm irrigation). The Delta Mendota and California Aqueducts are already used to divert excess storm water to the Los Angeles Basin, and could even reach the Colorado River Basin, if large reservoirs, pumps and pipelines were built. The issue of “how to store this vast amount of stormwater” (reservoirs vs. groundwater recharge) is an interesting one, which we will get to later.

Wastewater reclaimation in Durban South Africa. Gradually, tertiary wastewater plants are being built in California, providing reclaimed potable water and lowering the demand on supplies

3) TERTIARY WASTEWATER: A the risk of an “ew”, know that a growing amount of California wastewater is now being treated to drinking water quality, allowed to run to receiving waters (rivers and such which run to the sea), sold to places like golf courses and cemeteries, or run back into the aquifer. This trend began with California coastal communities, who were forever in trouble with regulators regarding contaminated storm runoff (stormwater which infiltrated sewer lines, overwhelming treatment systems by mixing in poorly-treated waste). Treatment plants were made larger with longer treatment times (so as to handle this “wet weather overflow”), while it became possible to treat wastewater effluent to drinking water quality using sand filters and ultraviolet light. This pretty much solved all wastewater effluent problems (at higher cost of course), yet “selling back” the treated effluent has a chance to offset this cost. If groundwater recharge can be successfully utilized (reducing the “ew” factor), then about 10% of all California water can be “recycled”.

4) HOME OR COMMUNITY CISTERNS: In the old days, people had “rain barrels” to capture precious water during storms. Since large plastic or metal cisterns are now available for about $1 per gallon (they are popular in rural areas), this system can be as simple as routing your rain gutters/downspouts to a well-placed 5,000–10,000 gallon tank (enough for about 2–4 months of dry weather use). If water is being delivered at about $0.02–0.05 per gallon, this can also be a big savings. The cistern can also serve as additional fire fighting reserve (sometimes water can be scarce during firefighting). The recommended means to use this rainwater might include reverse osmosis for drinking water (delivered to kitchen and/or bathroom tap), chlorinated/filtered water elsewhere (used for wash water and toilets…safe to drink but of a lesser quality than tap water). Small private water utilities (such as Culligan) could check on the system. Ironically, swimming pools (which have received a black eye during our water shortage) could serve a similar purpose. Both cisterns and pools could also be part of “water source heat pumps”, which are an environmentally friendly way to heat/cool homes. (Zakaras,2015)

Delta Mendota Canal and California Aqueduct Intertie-These canals deliver Northern California water South

5) PUMPS, PIPELINES, CANALS THAT SHUTTLE STORMWATER SOUTH : This may not sit well with some in the three-way California “water wars” (between Southern California, Environmentalists, and Farmers), but Northern California would appear to have the ability to refill its reservoirs periodically, with water to spare during wet winters (which occur about every 3–5 years, possibly changing with Global Warming patterns). The gigantic Delta Mendota Canal (which was built to deliver Sierra Nevada water to Southern California) has dried up recently, as there hasn’t been enough water to distribute to the Kern County farmers (this is why Devin Nunes and other Republicans have all those dead trees and signs reading “Environmentalists are Killing Ag” and the like, along I-5 down Bakersfield way). This has a long history, as the Salyer and Boswell families (who later formed Kern County Water Districts) dried up the Kern River (with diminishing returns), growing ill-advised and thirsty crops such as cotton. However, if Kern County were willing to build a large reservoir and pay the money, Northern California excess storm water could be pumped into the Delta Mendota and sold to Salyer/Boswell. Similarly, Delta Mendota/California Aqueduct water from the San Joaquin (or even Sacramento River excess if Twin Tunnels are built) could be pumped south relieving demand on Lake Mead (which is still extremely low, even after the rains and uses the Colorado River Aqueduct running to LA). In fact, the California Aqueduct already is used to fill L.A. Basin reservoirs Pyramid and Castaic Lakes (mostly serving the Santa Barbara area). Sharing storm runoff with LA may also provide necessary revenue to do repairs to the canals (to decrease subsidence and evaporation). (Becker,2022),(,nd),(, (,nd)

6) A NOTE ABOUT FUTURE WATER POTABILITY: A sidenote to all of this is that up to now, we have been pulling relatively pristine water from deep/ancient aquifers and mountain reservoirs fed by snowmelt and raging alpine rivers (a clean source). As such, these sources need little treatment (usually precipitation to take out minerals, some chlorination for bacterial kill). Everyone in the water business is worried about the future emergence of protozoans such as Cryptosporidium and Giardia, which can enter reservoirs through human contact and various other hosts (this would require filtration at great cost). Wells close to the surface often contain nitrates and other contaminants, and require additional (and expensive) treatment. As in the “Community Cistern” example, there may be a push to separate potable and non-potable water sources in the future, to both address cost and distribute declining water sources. (Rivard,2019)


Many types of groundwater recharging methods have been proposed

1) GROUNDWATER RECHARGING: This would be a great solution if it were easier to accomplish.

a) There are currently many unknowns regarding groundwater aquifers. These aquifers tend to be quite dependent upon the geologies surrounding them. Some are ancient aquifers that have been built up over eons, which tend to carry the purest water and are typically “capped” by impermeable geologies (such as clay layers or rock).

b) Shallow aquifers (0–50’ deep) are more likely to contain nitrates (which can result from ag fertilizer and animal waste runoff). Nitrates can be harmful to health, especially infants. Deep aquifers (more than 300 feet, let’s say) are more likely to contain salt poisons” such as arsenic and boron. Medium depth aquifers often contain iron and manganese, which can affect taste and corrode pipes, but are otherwise relatively harmless. All of the above can be successfully treated for drinking water, but sometimes don’t need treatment for strictly ag purposes.

c) There are aquifers under sandy soils that are easily reached. However, you might say that these aquifers are more prone to contamination. They probably “recharge” themselves successfully already during wet weather. Central Valley soils are notoriously sandy and the water table typically is close to the surface. The last few years, this aquifer has dropped (due to all the ag usage during drought), so this area may be the best to recharge.

d) Good luck recharging deep aquifers under impermeable layers, as they may require expensive pumping and distribution devices

e) Other ideas, such as permeable pavement, are thought to be a good way of helping replenish aquifers (Melillo,2023)

The California Aqueduct is scheduled to be boosted by twin tunnels directing additional Sacramento River water. Additionally, projects to repair “subsidence” (settling of the canal, slowing flows) and combat evaporation (solar panels?) have been discussed. Meanwhile environmentalists claim that even storm waters need to be retained as habitat and “flushing” of streams and Bay, while farmers are desperate.


a) The California Aqueduct and Delta Mendota Canal have the capacity to supply Southern California with Northern California’s excess storm water (they already do). The California Aqueduct is fed primarily from the Sacramento River, by pumps from the Stockton area Delta (where the San Joaquin and Sacramento Rivers meet before carrying water to the SF Bay) Similarly, the Delta Mendota Canal is fed primarily by San Joaquin River water from the Delta. Yet no one really knows the true environmental impacts of all this…how much storm water does wildlife need? Does pumping water from one basin to another introduce invasive species (some as yet unknown)? However, the viability of the California economy (and food delivery to the rest of the Nation) may depend upon shuttling of storm water here or there.

b) There are relatively simple means of conserving the water we already possess. One idea is covering the two large canals with solar panels to both generate electricity and decrease massive amounts of evaporation. Another is repairing canals that have subsided to increase flows, while avoiding leakage. (,nd)

All told, there may be many ways to better conserve and distribute California water, at least until the next “megaflood” occurs and the Central Valley becomes a gigantic inland sea! (,2023)

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Vern Scott

Scott lives in the SF Bay Area and writes confidently about Engineering, History, Politics, and Health