California's Limited Freshwater Supply - Part IV
(Originally posted February 02, 2017 on Blogger)
Perhaps the most important natural freshwater body in the state of California is the Sacramento-San Joaquin River Delta (Delta). It is formed by the confluence of the Sacramento and San Joaquin rivers. The Sacramento River is the state's largest river, with a natural annual discharge of ~22 million acre-feet. Before its waters were dammed and controlled, the rainy season river discharge rate could be as much as 650,000 acre-feet per second; a flow rate equal to that of the mighty Mississippi. However, the river is now controlled by state and federal-built water systems from which 4.72 million acre-feet/year is diverted for irrigation (not returned to the river to be fed into the Delta), and 491,000 acre-feet/year diverted for urban use (also not returned to the river). I will get to the water system built along both the Sacramento and San Joaquin rivers shortly. The Sacramento River is fed by numerous tributaries feeding into the Sacramento Valley from the Coastal Range and Sierra Nevada (see image below). As such, storms contributing rain or snow to any portion of this watershed are, to varying degrees, beneficial to the state's freshwater supply.
For thousands of years after the Younger Dryas, the Sacramento River had turned much of the Sacramento valley into a bountiful landscape populated what was once California's densest population of indigenous tribes. The river was a primary source of the once abundant Chinook salmon, and played host to a wide variety of flora and fauna.
But it was on one of the southernmost tributaries to the Sacramento River that sparked an influx of immigrants to the Sacramento Valley that would forever change the natural landscape and its people. Gold was discovered on the South Fork of the American River (see image above) at Sutter's Mill, and in the following years, over 300,000 immigrants flooded into the valley, half arriving by sea, the other half by land in what history has dubbed, the California Gold Rush. Immigrants from the young United States came in from the east, islanders from the Sandwich Islands (now Hawaii) arrived from the Pacific. Immigrants from Latin America arrived from the south. And all of them came at the expense of the indigenous tribes living in and around the valley. Some estimates put the Native American death toll at around 100,000 between 1848-1868.
The gold rush is what truly marked the beginning of the state's (it became a state in 1850) demand for freshwater; freshwater primarily used for irrigation and mining, and what can arguably be the end of the world for Native Americans.
The other major river feeding into the Delta is the San Joaquin River which flows through the San Joaquin Valley. Though not as wet a region as the Sacramento Valley (as mentioned in previous parts to this series), the San Joaquin Valley was still home to many Native Americans for several thousand years, most of whom relied heavily on both the San Joaquin River, and the now extinct Tulare Lake. If you've read my previous blogs in this series, you'll recall that engineering works along the San Joaquin River (dams, canals, pipelines, etc.) cut the Tulare Basin off from the San Joaquin watershed, thereby 'killing' Tulare Lake.
You may also recall from previous blogs in this series that farmers who attempted to irrigate their fields with water from the Sacramento and San Joaquin Rivers, were invariably met with flooding events after heavy rains (an rapid snow melts). Though, as mentioned before, farmers in the dryer San Joaquin Valley to the south, also had to contend with periods of droughts. Food for thought when we finally answer the questions about whether the state is still in a drought, and if our use of freshwater is sustainable.
The Delta is an inverted delta, meaning it's narrower towards the sea (Carquinez Straight) than it is inland. This unique feature, coupled with flow (now controlled) from the Sacramento and San Joaquin rivers is what keeps salt water intrusion at bay. However, salt water intrusion is still a threat, and a major challenge to deal with. Salinity stations exist throughout the Delta to ensure water quality; critical to the state's water system and all those who need it.
Another threat looming over (or under I should say) the Delta is the continued subsidence of its islands. Many are already below sea level, putting ever-more strain on the Delta's levee system. The islands were formed naturally over geologic time. For thousands of years, sediments were transported into the delta by the Sacramento and San Joaquin rivers; accumulating over time. As mentioned above, the Delta is an inverted delta, narrower towards the sea at the Carquinez Straight. The narrowness of the straight, coupled with tidal action caused the sediment to pile up enough to create marshes upon which grew tule and other types of bog-loving vegetation. Over time, the remains of this vegetation, coupled with sediments formed islands consisting of peat and tule.
For geology nerds; if left alone for a few million years, that peat would turn to lignite, then to bituminous coal, and ultimately anthracite. Who knows, perhaps in a few million years the bay area could have been the West Virginia we all know and love.
These islands were doing just fine until in the 19th century farmers began claiming them for agriculture. The very practice of agriculture, particularly in those days, inevitably led to to wind erosion of top soil. This coupled with oxidation began a subsiding trend that continues to plague the Delta to this day. I'll explain oxidation shortly.
To combat subsidence, farmers built earthen levees around the islands (you can see these with Google Earth). Those levees were built with the peat and tule of the islands themselves. Of course, this meant lowering the islands further in order to build the levees. You can't get somethin' for nuthin'.
With many farms now at or below sea level, farmers had to devise ways to keep their fields from turning into bogs. In order to do this, they had to install semi-continuous pumps to remove agricultural drainage to maintain a low water table (see image above). Of course, fertilizers, herbicides, and pesticides contaminating the groundwater can be pumped out into the Delta as well.
The organic composition of peat and tule mixed to the islands' regolith oxidizes in aerobic conditions, such as those present on island farms. Exposure to atmospheric oxygen accelerates the decay rate of tules and peat soil, converting the soil primarily to carbon dioxide and water (ironically). As peat soils decompose, the land "vaporizes" over time, and subsides further. It is estimated that 1.5 inches of soil is lost to oxidation annually. Combine this with wind erosion, and levee construction (and reinforcement), settling, and compaction... well, it doesn't take a rocket scientist to see subsidence if not a losing battle, then an increasingly expensive one to fight. A fight nature is willing to wage on a timescale no human can comprehend nor truly appreciate.
Some farms have already been reclaimed by nature, allowed to be flooded to take water pressure off other islands. Examples of this voluntary compromise to the delta include the Little Holland Tract, and Liberty Island. In fact, since 1980, 27 delta islands have been partially or completely flooded either on purpose or by mishap. In 2004, a levee breach allowed delta water to flood an island, requiring $90,000,000 to fix. This singular incident is only one of many smaller, yet expensive incidents that will only become more frequent with time. Additionally, millions of dollars are spent each year just to maintain the levee system in the delta. This sort of ongoing losing battle with nature reminds me of the Army Corp of Engineer's war with the Mississippi, as they constantly fight back the river from taking its natural course through the below-sea-level city of New Orleans. But that's another topic, and one already covered by John McPhee here.
In response to the ongoing battle, the state published the California Bays & Estuaries Policy (1974); a policy containing a set of guidelines on how to prevent water quality degradation in the delta and its estuaries. But findings from the Delta Risk Management Strategy appear rather bleak to me. Levees need seismic upgrades, but many are locally-owned and maintained, financed by landowners within the levees, with supplemental financing from the state (taxpayers). So approval for federal upgrades to the system is complicated. About 730 miles of levees, plus all the Suisun Marsh levees have been locally-owned and maintained for the past 130 years or so. 385 miles are federally maintained as part of the Federal Flood Management Project of the Sacramento and San Joaquin river systems. Being under the auspices of the feds, these latter levees are eligible for rehab by the very busy Army Corp of Engineers. With regard to seismic upgrades, it should be known that a 7.5 or greater magnitude earthquake in the Delta region could theoretically affect water conveyance to other parts of the state, leaving the parched south particularly vulnerable. Just some more food for thought when we answer the questions posed at the beginning of this series.
Flooding continued, with significant floods in the 1980s. In response to flooding, the Flood Control Protection Act (1986) was passed to allocate funds for levee improvements and flood-control plans to the tune of $12,000,000/year for 10 years. Not surprisingly this act has been extended beyond the original 10 years, and is likely to be extended ad infinitum and at increasing cost with time, as battling the inevitable becomes increasingly difficult. In fact, in 2006 two bond measures were passed to allocate more funds to the cause, and I doubt they'll be the last.
According to a report by the USGS, Delta islands have subsided by 9 to 26 feet below sea level since the 19th century. Perhaps it's time the state, feds, and local farmers stop the nonsense and allow these islands to be returned to nature. Even the USGS concedes in their report (linked above) that returning the islands to their natural wetland state is the intelligent thing to do. Though they didn't word it that way, they do write that allowing the islands to flood, the subsequent growth of marsh plants would sequester carbon through the accumulation of tule and peat, capturing sediments from the Sacramento and San Joaquin rivers, and ultimately reversing subsidence. What?! Nature had it right the first time?! Well butter my butt and call me a biscuit!
From the Delta, water is pumped through canals and pipelines to other regions of the state. About 120,000 acre-feet/year is pumped into the North Bay Aqueduct which supplies freshwater to both wine-famous Napa and Solano Counties. A large portion of Delta water is pumped into the Clifton Court Forebay, where it is pumped into the world-famous California Aqueduct by the Harvey O. Banks pumping plant.
Unfortunately, to get the water from the forebay into the aqueduct, requires lifting the water over 220 feet. An upgrade to the facility in 1986 now allows the pumping plant to lift 10,665 cubic feet of water per second into the California Aqueduct. I'll get to the kind of energy this requires in a moment; as much of California's hydroelectric energy produced by our water system infrastructure is consumed by that infrastructure.
Once in the aqueduct, the water flows south to the Bethany reservoir, which serves as a forebay for the South Bay pumping plant that supplies water to the South Bay Aqueduct, itself conveying water to Alameda and Santa Clara counties.
Other branches of the aqueduct are the coastal, east, and west branches. The coastal branch supplies the cities of San Luis Obispo, Santa Maria, and Santa Barbara with the help of 5 energy-intensive pumping stations. The east branch supplies the Palmdale reservoir, terminating at the Perris reservoir. The west branch continues south, terminating at the Pyramid and Castaic reservoirs, the latter supplying water to the western Los Angeles basin.
The other half of Los Angeles' water is supplied via the Los Angeles Aqueduct, which gets its water supply from the Owens Valley. Owens Lake is now an anemic, mostly dry endorheic alkali flat, as much of the water from the Owens river is diverted to the L.A. Aqueduct. Los Angeles also diverted water from Mono Lake. The L.A. Aqueduct and its environmental impacts both past and present deserves a blog of its own.
OROVILLE DAM & RESERVOIR
Now let's look at the state's major dams and their respective reservoirs, starting with Oroville. The Oroville reservoir was created by the Oroville dam, the tallest dam in the country and a key feature of the SWP as its flood gates help control flow into the Delta. After Word War II, vets returned to California in droves. Population increased, and the state realized an economic boom, which in turn led to more urban expansion. By 1945 the state realized its current water system would eventually be insufficient to support this growing urban population. At the time it was geared towards agriculture only. So a study was conducted by the Department of Water Reclamation and the California Department of Water Resources (then called the Division of Water Resources).
In 1951 the state proposed the Feather River Project (the direct predecessor to the SWP), which among other engineering feats, included building a dam on the Feather River at Oroville. Voters fought over approving the project, until major flooding cast its vote and construction on the dam began (1957). What followed was the Burns-Porter Act, which authorized the SWP.
The Oroville dam was completed in 1968, after some 40,000 trainloads of material (155 million tons) were brought in for embankments. Though not before a train wreck resulted in 10,000 gallons of diesel to burn into the atmosphere, and torch a hundred acres. As mentioned in previous blogs in this series, dams function to control floods, store water for future use, and if so equipped, provide electricity via hydroelectric turbines. Of course, to continue to serve these functions, dams must be maintained, or catastrophic failure can result. With respect to hydroelectric power, Oroville produces about 1,490 GWh/yr. With regard to flood control, the dam proved its worth when in 1964 one of the worst flooding events in terms of total discharge in northern California history struck. The dam was nearly over topped even with its spillway fully opened. Floodwater inflow subsided in time to allow the spillway outflow to do its job, reducing downstream flooding by 40%. However, this fact suggests this reservoir should be kept low to accommodate flood waters during wet seasons, as history has shown inflow from this catch basin can exceed outflow from the Oroville spillway. As we will see in this series, taxed spillways have failed in the past with catastrophic results.
SHASTA DAM & RESERVOIR
The Shasta reservoir was created by the Shasta dam built on the Sacramento River. Along with the Oroville dam, this dam is key in controlling flow into the Delta such that the extent of salt water intrusion into the Delta is limited. The Shasta hydroelectric plant produces about 1,806 GWh/yr. The dam has served the state well (I'll get to environmental impacts later), but increasing demand for water has led the Bureau to consider raising the dam in order to store more of it in the Shasta reservoir. In fact, some plans call for the dam to be raised an additional 200 feet, which would allow an additional storage capacity of 9.3 million acre-feet. That's in addition to the current storage capacity. It would also increase energy production at the power plant to 1,300 MWh/yr. Though, one has to consider whether or not increased capacity necessarily equates to the reservoir actually being filled to such, as that would require more water to come from more storms and thicker snow packs... neither of which seem to frequent the state.
TRINITY DAM & RESERVOIR
The Trinity reservoir is created by the Trinity dam. Completed in '61, it was part of the CVP and meant to provide flood control and irrigation to the San Joaquin Valley. If you'll recall from previous blogs in this series, the CVP was authorized by U.S. Congress when they passed the Rivers and Harbors Act (1935) which lead to the CVP. The CVP, like the SWP, being a system of dams, canals, pipelines, and the like meant to provide flood control, and a stable supply of freshwater to the state (the CVP to the Central Valley primarily).
The Trinity dam provides stable flow to the smaller Lewiston dam, the latter of which is a diversion point for Trinity waters into the Central Valley.
(NEW) MELONES DAM & RESERVOIR
Another dam authorized back in the mid 20th century to irrigate the fertile agricultural region of the Central Valley. The original dam built in '26 was 211 feet tall and stored 112,500 acre-feet, expanded in '44 to hold 450,000 acre-feet, though farmers wanted a taller dam capable of storing over a million. So in '62, the Flood Control Act authorized a final dam design that increased reservoir storage capacity to 2.4 million acre-feet, plus a new power plant capable of generating over 322 million KWh/yr.
I'm saving information on the environmental and human impact dams have until after we've covered the major dams and reservoirs of California. However, this dam and its reservoir deserve some attention with regard to these issues here.
Filling this reservoir meant flooding vast stretches of the scenic Stanislaus River, that once flowed with white water rapids in the spring and early summer. Filling the reservoir to its new increased capacity was halted, particularly by Mark Dubois, founder of 'Friends of the River' who chained himself to a boulder such that filling the reservoir would drown him. He was successful in that the reservoir was forever to be set at an 844-foot capacity (438,000 acre-feet).
However the ENSO event of '82-'83 sent a record-breaking volume of water into the river valley. With the new, higher dam in place, the waters were compounded and the valley filled, ultimately filling the reservoir to capacity, and even cresting the emergency spillway. The state took this opportunity to lift the 844-foot limit. However, the controversy surrounding this dam has made it one of the last large dams built in California since.
SAN LUIS DAM & RESERVOIR
This reservoir is formed by the San Luis dam, storing water from the San-Joaquin River Delta. Though, uniquely, water stored here is pumped uphill from the O'Neill forebay, itself fed by the California Aqueduct. It is therefore an off-stream dam and reservoir, and the largest of its kind in the country. This reservoir is jointly operated and maintained by the CVP and SWP. It produces 424 MW/yr, but I'm guessing a good chunk of that energy is used to pump the water uphill to it.
FOLSOM DAM & RESERVOIR
The hydroelectric plant at this site produces about 691 million KWh/yr. This dam was originally proposed way back in the '30s due to flooding in the low-lying state capital, something that was exacerbated in later years by the debris from hydraulic mining and levees built by the 'Forty-Niners' (gung-ho miners).
This dam is of particular interest because it protects the heavily-populated Sacramento area from flooding. However, the Bureau's Safety of Dams Program determined that insufficient safeties at this site put the Sacramento area at great risk of catastrophic flooding. In fact, many hydrologist and geologists agree that the Sacramento area is one of the most at-risk communities for flooding in the United States. Right up there with New Orleans.
As such, the state has implemented new flood protection projects--currently underway--to raise surrounding dikes by 7 feet, and create a new spillway with gates 50 feet lower than the existing spillway to allow more efficient evacuation of reservoir storage during flooding events. Sacramento's elevation is only 30 feet on average.
DON PEDRO DAM & RESERVOIR
The original capacity of this reservoir was only enough to irrigate farmland for a year in dry times. This worried farmers who had experienced multi-year droughts in the past (starting to see a theme here yet?) The expansion of the Don Pedro Dam was supported by the city of San Francisco, who had already completed the O'Shaughnessy dam that flooded the Hetch Hetchy Valley. So much for being the environmentally-conscious capital of the state.
THE NEW EXCHEQUER DAM & McCLURE RESERVOIR
The McClure reservoir is formed by the new Exchequer dam, called "new" because it replaced an older dam. The original smaller dam was built to provide flood control and stable flow for irrigation. However, by 1950 it was already insufficient in supplying the expanding agricultural sector and population of the area. So the Merced Irrigation District took it upon themselves to build a bigger, "better" dam, implementing an untested design of vertical zones of compacted, alternating layers of course and fine regolith. However, the final product leaked up to 100 acre-feet per SECOND, which apparently seemed acceptable. The California Division of Safety of Dams didn't see it as such, and ordered them to patch up the leaks (1985).
Proposals to raise the dam in order to increase the reservoir's capacity are on the table now, in response to the ever-increasing demand for freshwater (another theme we should recognize by now). However, raising the dam may be a fruitless endeavor as this dam has never reached capacity in all its years of existence. So it isn't much of a stretch to imagine a higher dam will just look even more obnoxious when there wasn't even enough water to fill the lower version to begin with. I'm just sayin'.
FRIANT DAM & MILLERTON RESERVOIR
Millerton reservoir is formed by the Friant dam, originally built to provide irrigation to the San Joaquin Valley. It was funded from the Emergency Relief Appropriation Act (1935), and under the control of the CVP (itself authorized by the 1935 Rivers and Harbors Act).
There are plans to expand this reservoir (raise the dam by up to 140 feet), in order to triple its capacity. Additionally, there is another proposal in place calling for the building of another dam (Temperance Flat dam) downstream in order to capture floodwater otherwise spilled from the Friant dam. The Temperance Flat dam would also increase the storage in upper San Joaquin River basin. This all, of course, in response to growing demand (theme alert!).
PINE FLAT DAM & RESERVOIR
The primary purpose of this dam, built on the Kings River, is for flood control, protecting about 300 square miles of land. Once open to the public, the site was closed off after the terrorist attacks of September 11, 2001. Due to the limited capacity of this reservoir, an average of 200,000 acre-feet must be released each year in order for it to maintain room enough to capture flood waters when they occur. There are talks to increase the dam height, thereby increasing storage capacity, and ultimately increasing power production from its hydroelectric plant (currently produces 420 million KWh/yr).
There's little point to post the volume chart on this site since it is primarily a flood control reservoir of minimal capacity.
CASTAIC DAM & RESERVOIR(s)
This site has a hydroelectric power plant with a capacity of 11 MWh/yr, but it is only used when needed (like summers in L.A. when everyone with an A/C sets it to 58 degrees F). This dam holds water transported to it by the California Aqueduct. Though tiny Castaic Creek and the trickling Santa Clara "river" feed into it, they provide very little of the reservoir's water.
As mentioned above, this reservoir sits at the terminus of the California Aqueduct, and supplies the western portion of greater Los Angeles with drinking water... for lawns. From Castaic, water flows through the Foothill feeder pipes some 20 miles to the Jensen Filtration Plant near San Fernando where it connects to the municipal water system for distribution... to lawns. The Sepulveda feeder takes water an additional 45 miles south to provide water to Los Angeles proper, as well as municipalities of Orange County. About 12 million lawns, er, people get 100% of their was from the Castaic reservoir and its feeder systems.
Contrary to popular belief, south does not necessarily mean downhill. The Nile would be a good example of this. This holds true for southern California as well. Between the Delta in the north and lawns in the south stand the Tehachapi Mountains. Water must be lifted up and over these mountains before they can ever reach the southern reaches of the SWP's system.
To accomplish this, let me introduce you to the Edmonston Pumping Plant.
Water must be lifted 2,882 feet over the Tehachapi Mountains in order to continue to the water-scarce south. In order to accomplish this incredible feat, pumping plants are needed to lift the water. The Edmonston Pumping Plant alone lifts water 1,926 of the 2,882 feet necessary to get over the Tehachapis; a world record holder. To do this, it uses two galleries of 7 motors. Not just tiny gutless motors like this:
But fourteen 80,000-horse Goliathans, each consuming up to 60 MW! Energy hogs, but necessary if the state's population south of the Tehachapis (not connected to the Colorado) wants to survive (and grow lawns). Pumping stations are vital components to the CVP and SWP. In fact, of the 6,500 GWh/yr of hydroelectric energy produced by power plants in the SWP, 5,100 GWh/yr of it are used to power the pumping plants that keep its waters flowing. Gravity, as NASA would agree, is a bitch.
Probably the toughest well in the state is the gravity well.. get it?!
I'm not posting volume statistics on Pyramid, or Castaic, or any other reservoir artificially filled by the California Aqueduct as their volumes are not necessarily representative of drought conditions. Throughout much of the drought, Pyramid was at or near capacity for example. It's reservoirs that are filled by dammed rivers (damned rivers) that we ought to look to for a truer measure of what we're facing. This is why blogs and news articles citing a filled-to-capacity Pyramid "lake" are misleading. It took four blogs in this series to be able to say that. Whew.
PERRIS DAM & RESERVOIR
If Los Angeles wins the bid for the 202something Olympics, then this reservoir will likely be the site for some sort of row boat race. Yay. In 2005, this reservoir was drawn down by 20% due to safety concerns that a large earthquake could partially breach the dam and catastrophically flood the urban area below (a reason why the Sepulveda and Chatsworth reservoirs will never be filled). The flood risk to the dense population of terrible drivers is just too great. Seismic upgrades, however, are being performed on the Perris dam as I write this, and should be finished soon. This site is another example of why artificially fed reservoirs are poor indicators of the state's water health.
Well dammit. I think I have to write ONE more blog to complete this series. In it, I promise, I will answer the questions of whether California is in a drought, and if our use of water is sustainable. I WILL do it! But for now, I hope we recognize the themes that droughts are inevitable, our water system has vulnerabilities, water demand across the state is increasing, and maintaining and expanding our water-supplying infrastructure have and will invariably have environmental costs attached to them.
Please consider continuing on to Part V by clicking the link below:
For fun, have a look at these coordinates on Google Earth