While the saying, “too much of a good thing,” sounds pleasant at its core, water managers take that very seriously when it comes to managing salt, or salinity, in the water supply. Water managers across California are responsible for providing a clean and safe drinking water supply, and salinity management plays a critical role in the quality of water that is provided to communities.
While salt is composed of natural elements commonly found in soil and water, how is salinity managed to support a diversified water resource portfolio? What programs are implemented to help maintain salt concentrations within acceptable levels?
A webinar, presented by Orange County Water District, took an in-depth look at how salinity is managed in Southern California and the Santa Ana watershed.
The presenters:
Warren Teitz is the manager of the resource development team at the Metropolitan Water District of Southern California, where he and his team manage programs and planning issues for groundwater, stormwater, desalination, salinity management, and other cross-cutting resource issues in Metropolitan’s Water Resource Management Group. This includes implementing Metropolitan’s future supply action funding program, which funds research to remove development barriers for local water resources. Mr. Teitz has over 25 years of experience in California’s water industry, serving on the boards of the Southern California Salinity Coalition, Cal Desal, and Multi-State Salinity Coalition.
Mark Norton is the Water Resources & Planning Manager at the Santa Ana Watershed Project Authority, a joint powers authority organized to support water resources in the Santa Ana River watershed. His background includes 40 years of engineering experience in a broad range of civil engineering projects. Mr. Norton led the development of the first Integrated Regional Water Management Program for the Santa Ana River watershed and currently oversees the IRWM plan known as the One Water, One Watershed plan. He also serves as the administrator for the Lake Elsinore and San Jacinto Watershed Authority, a joint powers agency created to improve water quality for Lake Elsinore and the San Jacinto River watershed.
Greg Woodside is the Executive Director of Planning & Natural Resources at Orange County Water District, where he oversees the preparation of the District’s environmental documents, implementation of the District’s resource management programs, and compliance with the Sustainable Groundwater Management Act. Mr. Woodside is a registered geologist and certified hydrogeologist in California with 30 years of experience in water resources management and hydrogeology.
WARREN TEITZ: Southern California Regional Salinity Management
What is salinity? It’s a measure of salts or minerals that are dissolved in water, commonly expressed as total dissolved solids or TDS.
The graph at the lower right shows the mineral composition of the Colorado River; the sodium and chloride (what is commonly thought of as salt) is shown in red. These minerals commonly cause problems for agriculture. The minerals shaded green and blue will cause problems with scale, typically for household appliances and water heaters.
Salinity occurs both naturally and from human sources, such as agricultural runoff or urban uses. It can cause several problems:
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- Drinking water quality and taste: high salinity water has an unpleasant taste and smells like sulfur.
- Scale build-up: Showerheads, water heaters, and anything using hot water will potentially have problems with the scale that can occur with high salinity water.
- Crop yields: Salinity affects agriculture crop yields and turf irrigation.
- Groundwater: Salinity affects the use of groundwater basins. “Before SGMA, there were basin plan objectives for groundwater basins and salt nutrient management plans,” said Mr. Teitz.
- Recycled water: Recycled water can be higher in TDS (total dissolved salts), affecting the use and cost of recycled water for irrigation and other uses.
Salinity is an age-old problem. Irrigation in Mesopotamia started 1000s of years ago, and the Sumerians developed sophisticated irrigation systems. But they were also challenged by salinity that built up over the centuries of using water from the Euphrates and the Tigris.
The picture shows a map of one of those early irrigation systems; the main canal comes in from the top and then moves from east to west, with fields in the middle and circles representing the cities.
“This is basically GIS on a clay tablet,” said Mr. Teitz. “There was very sophisticated agriculture there, but they did suffer from salinity. And they came up with management strategies that we still use today: leaching, fallowing, and crop substitution. As their fields became too saline for wheat, they switched over to more salt-tolerant barley. So salinity is an age-old problem. It’s a problem here and today, and it’s going to be with us into the foreseeable future.”
The graph shows the salinity (TDS) of the imported water supplies managed by Metropolitan Water District: The Colorado River and the State Water Project.
Mr. Teitz noted three things about this graph:
The first is that Colorado River water is twice as saline as the State Water Project, ranging from about 580 mg/L to 620 mg/L; the State Water Project is roughly half of that.
The second is that the State Water project varies significantly from year to year, depending on the water year type and the flows through the Delta. Drier years bring higher salinity water, such as 2015; in wetter years such as 2017, the salinity is lower. The Colorado River, by comparison, is buffered by storage.
The third takeaway is that the salinity in the Colorado River is gradually declining, mainly due to the successful efforts by the efforts of the Colorado River Salinity Control Forum collaborating with Metropolitan and other California water agencies and states in reducing the salinity of the Colorado River.
The Colorado River watershed was once covered by an inland sea (or at least most of it was), so salt-laden mineral deposits are all over. The most problematic is Mancos shale, a type of mineral deposit prevalent in the basin; the salt in that deposit is very soluble.
In the watershed, the headwaters of the Colorado River are pristine, but as it flows towards the west, the tributaries flow into the river, and the salinity rises. The salinity comes from natural sources, such as the highly saline springs that flow into the tributaries and agriculture.
“Metropolitan collaborates with the Colorado River Salinity Control Forum to manage salinity in the basin, and I would say it’s been a success,” said Mr. Teitz. “The forum is controlling over 1.2 million tons of salt from entering the Colorado River every year. This leads to a reduction in over 110 milligrams per liter of salinity at Metropolitan’s intake.”
Mr. Teitz noted that one acre-foot of Colorado River water contains about .8 tons of salt, roughly about one ton of salt per acre-foot. By comparison, the water flowing in at Paradox Valley, one of the hypersaline springs, is 250,000 milligrams per liter or 340 tons of salt in one acre-foot, or about four freight cars of salt in each acre-foot.
“If you look at what the forum is controlling, that’s 1.2 million tons of salt every year,” said Mr. Teitz. “That’s like 12,000 boxcars of salt that are not entering the Colorado River every year because of these control actions that the forum is implementing.”
One of the reasons why controlling salt on the Colorado River is important is the economic impact of the salts. The graph shows those impacts if salinity levels are maintained at the 2017 implementation levels, forecasted to 2035.
“On the Lower Colorado River, we’d have up to half a billion dollars a year in damages; more than half of that would be agriculture,” said Mr. Teitz. “As we move into Metropolitan and the Orange County service areas, the damage is switched over to more urban impacts, residential and commercial. Zooming into Orange County, almost 40% of the damages are coming from groundwater and recycled water use. And that’s because Orange County has the magnificent Orange County groundwater basin and also the groundwater replenishment and other recycled water projects.”
The Southern California Salinity Coalition
Recognizing that, Metropolitan, the Bureau of Reclamation, and other agencies completed a pivotal study, the Salinity Management Study, which had some major findings and led to some important actions. One of the findings was that the region had a 600,000-ton salt imbalance, meaning more salt came into the region than was being removed through wastewater outfalls and natural outflow. Importantly, the study found that about half the salt coming into the region was from local sources rather than imported water. As a result, the report called for establishing the Southern California Salinity Coalition.
“Metropolitan, as a result of the study, came up with a blending target of 500 milligrams per liter on an annual average when there was adequate State Water project available,” said Mr. Teitz. “In drought years, we can’t meet that target, but in most of the years, we can shoot for that 500 milligrams per liter goal.”
The Southern California Salinity Coalition, comprised of regional water, wastewater, groundwater, and watershed agencies, was founded in 2000 with the mission to work collaboratively to minimize the adverse effects of salinity on water systems, which is accomplished through research, advocacy, and outreach.
The Coalition funds studies that will impact and inform regulations and help water agencies address salinity.
One study completed in 2018 looked at the long-term salinity trends of rising salinity in wastewater. The graph on the lower right shows the rising salinity levels flowing into the wastewater treatment plant growing over time; the gap between the source water and the influent is also increasing over time.
The Coalition is currently funding a study of integrating the Carlsbad seawater desalination project supplies into San Diego’s distribution system; it is a follow-up study to the Water Research Foundation study, with a few years of integration to see how it’s benefiting the region. The Coalition has also funded studies of water softeners, recycled water irrigation, and economic impacts.
Advocacy
Advocacy activities include studies to inform the Model Water Efficient Landscape Ordinance on leaching allowances for recycled water under irrigation, and conducting a desalination research needs survey.
In terms of outreach, the Coalition is working in partnership with CUWA, Cal Desal, and other associations to develop briefing materials on water reuse that promote the water recycling and water reuse projects that water agencies across California are implementing and to discuss the challenges of achieving 100% reduction in discharges to the ocean. In addition, the Coalition has a summit planned for Fall of 2021.
The Coalition also funds graduate fellowships at $10,000 per year for a two-year cycle. “We’re looking for graduate students who are working on any topic related to salinity management, brine management, recycled water, and salinity, so it’s quite a broad area,” said Mr. Teitz. “They can be white papers or technical studies. You can find more on our website about that. We collaborate with the National Water Research Institute on implementing those fellowships.”
“I think that’s very important,” he added. “This is setting up the next generation of water managers and researchers in addressing salinity issues in the region.”
Participating in the Southern California Salinity Coalition
“Please join us,” Mr. Teitz said. “We’re looking to expand our membership. And it’s an opportunity to collaborate with peer agencies that have common salinity management issues. We’re currently implementing a multi-year research program to address relevant challenges that we’re experiencing right now. It’s an opportunity to partner with other associations and other agencies on some of these challenges. Our goal is to communicate compelling information, not just to the public but also to regulators, legislators, and other stakeholders and decision-makers.”
Find out more about the Southern California Salinity Coalition by clicking here. https://www.socalsalinity.org/
MARK NORTON: Salinity management in the Santa Ana River Watershed
Next, Mark Norton, Water Resources & Planning Manager with the Santa Ana Watershed Project Authority, discussed the region’s brine disposal efforts and other salinity management activities in the Santa Ana watershed.
The Santa Ana watershed is the largest coastal stream system in Southern California, covering about 2840 square miles. The watershed spans Riverside County, San Bernardino County, the northern portion of Orange County, and a sliver of Los Angeles County. There are 66 cities and about 97 water-related agencies. The population is about 6 million people; it is expected to rise to about 9 million people by 2050.
The Santa Ana Watershed Project Authority (SAWPA) is a joint powers authority; member agencies include the Inland Empire Utilities Agency, San Bernardino Valley Municipal Water District, Eastern Municipal Water District, Western Municipal Water District, and Orange County Water District.
When SAWPA first started, the focus was on salinity management. The first project was the Inland Empire Brine Line, which was initially called the Santa Ana Regional Interceptor. In addition, SAWPA serves as the convener of multi-agency task forces called roundtables. SAWPA also has developed the long-term Integrated Regional Water Management Plan for the watershed called One Water, One Watershed.
SAWPA was established in 1972; after close to 40 years of litigation over water rights and water quality, there was a desire for upstream and downstream interests to work together. The most pressing needs were to ensure that the groundwater basins were protected and to address the salt migrating down through the Santa Ana River to Orange County.
So where is the salt coming from? Dairy manure is very high in salt; at one time, the Chino Basin had the highest concentration of dairy animals in the nation, with approximately 350 dairies and over 300,000 dairy cows in a 20 square mile area. Agricultural practices such as fertilizers can add salts; formerly, there were large swathes of citrus and other agricultural lands across the area. That has now mainly been developed; however, the salts from dairy manure and ag lands are still within the soils, migrating down into the groundwater basins and unfortunately contaminating many of them.
In addition, there is salt entering the basin from the Colorado River and the State Water Project supplies, which leads to an imbalance of more salt being brought into the basin than salt leaving the watershed. This was a significant problem facing the watershed that SAWPA sought to tackle as one of its initial missions.
“To give you a sense of the scale, imagine 37,000 dump trucks lying end to end, filled with salt; that is the amount of salt being added to our watershed,” said Mr. Norton. “This gives you a visualization between LA and Las Vegas, all the dump trucks of salt. It’s hard to imagine that much salt being added every year. But that was the challenge that we were facing.”
Water recycling is a major focus of the region’s water portfolio, and they are leaders in this area, particularly in Orange County with the tremendously successful Groundwater Replenishment System Project.
“Water recycling is being promoted and supported throughout the upper watershed,” said Mr. Norton. “We want to use this as many times as we possibly can, but with water recycling, we know that if the salt levels go too high, then it cannot be recycled. So there needs to be a solution.”
This led to the construction of the brine line, which is a pipeline that stretches 93 miles from the Inland Empire to the Pacific Ocean. There are various branches spread across the upper watershed. It varies in size from 60- to 84-inch diameter; the capacity is 30 to 36 million gallons per day. Currently, about 13 million gallons a day are being put into the brine line. There are 24 direct connections which include industrial, desalters, and domestic waste.
Salinity concentrations range between 3000 to about 5000 milligrams per liter, far less than the ocean’s salt levels. This system removes about 50,000 tons of salt each year.
The brine line extends from the Huntington Beach Treatment Plant up through Orange County, generally paralleling the Santa Ana River into the Chino Basin up to San Bernardino. There is also a branch that extends up the Temescal Valley to the Eastern Municipal Water District.
Brine wastewater is produced from various industrial activities and human uses. For example, power companies often have cooling towers that concentrate the water and salts, which cannot be sent to a wastewater treatment plant. Industrial processes such as computer chip manufacturing need ultra-pure water, so the water is purified, and the high saline water has to be disposed of. Food processors also use the brine line. And, of course, all the reverse osmosis desalination groundwater plants throughout the watershed use the brine line.
The brine can be harmful to freshwater plants and animals, so collecting the brine through a pipeline was the way to solve the problem.
“We recognized that we needed to do this to ensure water recycling, the wastewater treatment plants really couldn’t accept this water, and the ultimate place it had gone to historically was the ocean,” said Mr. Norton. “But before it is discharged to the ocean, it’s sent down to the Orange County Sanitation District’s Huntington Beach plant, where it is treated and then disposed of into the ocean.”
“We have a very keen interest in protecting our watershed. Making sure that we can move these salts out safely helps our natural resources, both the surface water as well as the groundwater, that so many people and so many companies are dependent upon,” he continued. “Our long-term goal is to ensure that we have a sustainable groundwater and watershed overall for future generations.”
Several industries benefit, including the power industry, bottling companies, water treatment companies, and water softener companies. It is a valuable asset that is oftentimes under the radar as a lot of infrastructure is, noted Mr. Norton.
“Many people aren’t aware that we have this, and we’re doing all we can to make sure that we effectively market this and share it with any developers that we have this pipeline that’s available and can be tapped into.”
In terms of cost, the brine line is a good deal compared to other means of disposal, such as truck disposals or using tankers. The graph shows the comparison with other methods; in regions that don’t have a brine line, it costs about 25 cents per gallon or $250,000 per million gallons. That cost drops dramatically with a brine line connection.
“It is still a challenge; it is still expensive, but nevertheless a lot less expensive when you compare it to the alternatives,” said Mr. Norton.
Salinity management is also addressed through SAWPA’s roundtables.
“Our efforts are really to work with the Regional Water Quality Control Board to ensure that we are looking at the collaborative solutions,” he said. “The task forces that we have, particularly with the current Basin Monitoring Program Task Force, look at trends with TDS and nitrate. We look for ways we can resolve challenges and improve our efficiencies. Our relationship with the regional board in conducting joint salinity studies and implementation is a hallmark of success within many other regions across the state. What we have done has been a template for many others as they embark upon salt and nutrient management plans.”
Back in 1996, the group decided it was time to update the assumptions made when the first basin plan was developed in 1972. So a Nitrogen TDS Task Force was established, which had a very detailed and extensive study conducted to really look at the water quality objectives for nitrogen and TDS, analyzing over 1800 wells and 20 years of data.
“Some of the successes from that is that we conducted the first maximum benefit demonstration in the state of California for salt management,” said Mr. Norton. “This provides some flexibility that exists under the law and complies with the law.”
Another sign of success that continues today is that the Regional Board has come to view the Task Force as a clearinghouse for all TDS and nitrate-related issues to resolve conflicts and allow for efficiencies, so there is very little objection or dissent when they bring amendments to the regional board. In other regions, a basin plan amendment may be far less successful.
“I think we largely avoid a lot of the litigation that you’ll see in other regions,” he said. “Oftentimes, you look at agendas in other regions, and there are often long lists of litigation cases that they have to deal with. So I think the collaborative roundtables that we have are a tremendous success.”
The Basin Monitoring Program Task Force was next established in 2004. SAWPA agreed to do an update every three years to look at the trends with the nitrogen TDS for all the groundwater management zones in the watershed, and to develop an annual report for water quality focusing on the nitrogen TDS. They also periodically do a Santa Ana River waste load allocation, which is basically a 20-year projection of what the wastewater treatment plants can expect as far as how much they are recycling and how much they will dispose of down into the Santa Ana River.
“The river itself is primarily an effluent-dominated river flow,” he said. “So we want to make sure that we’re continuing to comply with the objectives to protect those groundwater basins throughout the watershed. As a part of that process, we’ve just completed s waste load allocation that we’ll be bringing to the regional board as a basin plan amendment. Currently, our big focus is to look at what modifications to some of the things that we’re doing are needed in light of the 2019 amendment to the recycled water policy that the state board recently passed, particularly for the salt and nutrient management plans.”
Drought impacts
Another challenge is this next round of drought that we’re entering into. Drought impacts water recycling efforts because low flows in the Delta cause salinity to increase in the water delivered through the State Water Project. When the source water is delivered to customers, they use it, and it’s sent to wastewater treatment plants. Overall, the wastewater treatment plants can generally comply with their discharge permits during drought cycles, but there is little margin for error.
“This increases the treatment costs,” said Mr. Norton. “If we’re not able to comply with those efforts, it becomes really unaffordable.”
The Regional Water Board recognizes that TDS levels do change, so one of their priorities is to look at how they can develop permits to address the multi-year nature of drought cycles. One of the actions was for SAWPA to conduct a joint study with the Southern California Salinity Coalition to look at drought impacts on salinity in the region.
“Typically during a drought, there is a big emphasis on water use efficiency, so as a result, water use drops, but the increment of salt is maintained there, so an increase occurs. So you can see that gallons per capita per day are dropping over time,” he said. “This is looking at a snapshot of about eight years, including the previous drought period that we went through.”
“What that study showed is that over that eight-year drought period, on a per capita basis, water declined by about 15 gallons per capita per day, resulting in approximately the 25 milligrams per liter of TDS increase. It demonstrated that there are some impacts from local and statewide conservation.”
Based on this study and discussions with the regional board, the next steps are to work with the regulators as they have the flexibility actually to look at how the permits are written. Rather than establishing permits based on the monthly average, they are considering modifying the averaging period to a ten-year rolling average in compliance with the discharge permits to account for drought cycles and the impacts from water use efficiency.
“This study has been very instrumental in helping us to leverage the impacts and to encourage a more streamlined permitting process and a more effective permitting process as well,” said Mr. Norton.
In conclusion …
“The overall benefit of our regional salinity management for our multiple agencies is that it’s been a cost-effective compliance approach,” said Mr. Norton. “We have the regional board staff at our multi-agency task force efforts. The Basin Monitoring Program Task Force staff and regional board staff sit together at these meetings. That builds the trust that I think has been invaluable in our region.”
“One Water, One Watershed. We have been very fortunate in having grant funding that has been brought forward to help offset some of the costs for desalination efforts, helped to pay for the groundwater replenishment system project, and has increased that collaboration that is really so important in integrated planning. And, of course, our brine line. It has just been a tremendous piece of infrastructure that has benefited this entire region and this entire watershed by reducing the costs of getting rid of the salt that is building up in the watershed. By having this brine line, we can take it, treat it, and then out to the ocean for disposal.”
GREG WOODSIDE: Orange County Water District
Then Greg Woodside, Executive Director of Planning & Natural Resources at Orange County Water District, then discussed how salinity is managed in the basin.
The Orange County Water District manages the groundwater basin in North and Central Orange County. Their service area is just downstream of Prado Dam. The District has recharge basins along the Santa Ana River in Anaheim and Orange; they also infiltrate or recharge recycled water from the GWRS Groundwater Replenishment System pipeline. The District injects recycled water produced through a joint project with the Orange County Sanitation District into the seawater intrusion barrier shown towards the bottom of the map on the lower left.
The map on the upper right shows the two primary management zones defined in the regional board’s basin plan: The Orange County Management Zone is shown in yellow, and the Irvine Management Zone is shown in pink. The District’s active recharge activities are in the Orange County Management Zone.
The Total Dissolved Solids (TDS) water quality objective in the Regional Board’s Basin Plan is 580 milligrams per liter, which was selected to reflect historic water quality from 1954 to 1973.
The map shows the average total dissolved solids at production wells within the basin from 2015 to 2019.
“This gives us an indication of the overall trends in TDS in our basin in an average sense,” said Mr. Woodside. “Around the periphery of the basin to the north and east, there are some wells that are over 700 shown in pink or darker blue circles. In the middle of the basin, there are wells where a lot of the TDS is roughly 500 to 600. And then down towards the coast, you see a cluster of wells or ag wells where there’s a lot of that green dots indicating from 350 to 500 milligrams per liter of TDS.”
The chart on the slide shows the water needed to recharge the Orange County Management Zone. Mr. Woodside pointed out that the chart excludes imported water. “Our imported water used for recharge is quite variable. We’re not recharging any this year. Other years we’ll recharge up to 60-70,000 acre-feet of imported water.”
“Looking at all of our supplies except imported water, you see our biggest percentage of recharge water is our recycled water from the GWRS,” he said. “So 45% of our supplies would come from that source. This is a 2025 estimating condition; we are currently expanding our supplies for GWRS water. We’re constructing 30 additional million gallons per day of treatment capacity right now. So this reflects when that’s completed. And the other numbers are average conditions for the year 2025.”
Other sources of recharge include:- Stormflows on the Santa Ana River, primarily captured at Prado Dam, 17%
- Santa Ana River baseflow, 17%
- Subsurface inflow, which is water that coming into the basin from the northeast and the east, 15%
- Deep percolation of precipitation and applied water, which is the percentage of water from watering lawns, irrigation activities, or precipitation that infiltrates down to the aquifer, 5%
- Alamitos Barrier, 1%
The chart on the right shows the salts that are in the source waters, with subsurface inflow accounting for 43% of the salt coming into the basin through recharge.
“The thing that’s quite striking here is that the GWRS provides 45% of the water that we recharge, but only 9% of the salts,” said Mr. Woodside. “That’s because the TDS of the GWRS water is so low. Compare that to Santa Ana River baseflow that provides 17% of the water in terms of the volume, and 27% of the salt.”
The Groundwater Replenishment System is a joint project of Orange County Sanitation District (OC San) and the Orange County Water District. OC San provides the primary and secondary treatment; Orange County Water District provides advanced purification and distribution for use; then, most importantly, OC San also treats the brine.
The slide shows the TDS of four terms. The basin water quality objective is 580 mg/L. The average groundwater quality is a statistical calculation for the OC Management Zone calculated at 600 mg/L. The influent into the GWRS has a TDS of 1000; after treatment, the water has a TDS of approximately 50 mg/L.
“The salts are removed by reverse osmosis,” said Mr. Woodside. “Then OC San takes that brine back from us, and then it’s discharged to the ocean. So we benefit by being a coastal agency with access to an ocean discharge system that OC San operates. That’s an enormous benefit for us for salt management.”
To illustrate this, he presented a time series plot from two of their wells, one in the shallow aquifer and one in the principal aquifer, showing chloride concentrations through time. The first dashed blue line is when the GWRS system came online in January of 2008. The plot shows that in the principal aquifer, the chloride concentration was roughly around 80 to 100 mg/L, but six years later, the chloride had a noticeable decline.
They have mapped the wells in the area to show the migration of the recycled water and the decline in the chloride concentration. This has also been verified through other measures.
“They all show this decline of the chloride concentration, which is an improvement of water quality. So we identify when the recycled water has reached wells within 10 to 20% decline of the chloride concentration. So this well is about 2.7 miles downstream of the basin, which translates to six years of travel time with a velocity of two meters per day. So we can map a series of wells and then draw a contour map of the arrival time of recycled water.”
Mr. Woodside presented a map of the shallow aquifer with wells 200-250 feet below the surface. This is based on measurements of the declines in chloride due to the GWRS water.
“As the water migrates to the West downgradient, it also migrates vertically downward,” he said. “In fact, the deeper aquifer, the next set of aquifers down is where the faster travel occurs. This has travel times out to eight years. This work was done in 2017. So if we were to update this, now, you’d see travel times that would go out to 11 or 12 years.”
The map on the right is of the principal aquifer, which shows that the water has traveled much further. “So in eight years, it’s all the way out to the just past the I-5 freeway,” said Mr. Woodside. “This is a rapid flow path to get this kind of distance in just eight years. It’s an improvement of water quality that spreads over this entire area shown here based on the recharge of the recycled water.”
The slide on the right is a cross-section of the aquifer with the selected wells shown, illustrating the vertical dimension of the movement. “It’s traveled about 200 meters vertically, and laterally, it’s traveled about 8000 meters, from 2008 to 2016. If we updated this, currently to this year, the migration would be even further to the west.”
He then presented a similar slide showing Fountain Valley and Huntington Beach, where water is injected to control seawater intrusion. “The injection to manage seawater intrusion also replenishes our groundwater basin. So the water that we inject travels down gradient, and so you see these areas that indicate where the recycled water is traveling to. On the left side of the barrier, the water travels mostly to the north and then to the east. We have highly variable geology down here. So we have different flow paths depending on which aquifer we’re in.”
In conclusion …
“Our Orange County Management Zone’s TDS is improving due to the GWRS water recharge,” said Mr. Woodside. “When we started GWRS in 2008, we were infiltrating roughly 70,000 acre-feet per year. By 2023, we’ll be recharging on the order of 130,000 acre-feet per year of the low TDS GWRS water. So that’s improving our sources of supply. And as we improve those sources of supply with recharge, then our overall OC Management Zone TDS declines, improving water quality. Since our Santa Ana river supplies are an important part of our recharge to the basin, the TDS of the quality of the Santa Ana River is an important factor for our groundwater basin quality. And with that, I’ll conclude.”
Q&A
QUESTION: Have the results of SAWPA work regarding the salinity apply to other regional water quality boards, and has this been shared with these other regional agencies?
Mark Norton: “There are a couple of forums by which we do share. One is the Southern California Salinity Coalition. We have multiple agencies there, and we share the results and successes that we experienced with salinity management in that forum. The other is that all the Regional Boards’ Executive Officers and support staff get together periodically to share their results and lessons learned with other regional boards. And we are very happy to know and work with our regional board staff. They’re just tremendous. And we know that they do share with others … for example, the maximum benefit demonstration was really a landmark of success. The regional board and we were the ones who first introduced this concept. And it is within Porter-Cologne law to allow that, and we were able to make that demonstration and now is being applied in other regions.”
QUESTION: What is causing the rise in chloride concentration after the big dip?
Greg Woodside: “For the wells that we were showing in our presentation that the chloride declined and then it had an increase for some time. What was going on there was that we shifted our recycled water between different basins. One of the wells I was showing is very close to the flow path. And so if we shift the recharge of our recycled water to different basins, it actually changes what happens downgradient. So it’s a reflection of how we shift the recharge of our recycled water among different basins, which is reflected then downstream. So we’ll see variations downstream because of the way we operate our facilities.”
QUESTION: Given the current lack of salt removal in the Paradox Valley, what are the long-term consequences for SoCal’s TDS? And when will those consequences hit us?
Warren Teitz: “You’re right. Paradox Valley was knocked out last year due to some seismic activity. And the Bureau has kept it off as they study what’s causing that. At the same time, the Bureau has been working towards an EIS for a replacement project. That EIS was going to recommend a no-action alternative. Due to the actions of Metropolitan, the Southern California Salinity Coalition, and many other agencies that are on the call today, we were able to send a letter in and get the Bureau not to issue a no-action alternative. And we’re going to be looking at a couple of different alternatives to managing that salinity from paradox valley that includes accelerating on-farm and off-farm interventions, so trying to get that same amount of salinity control through managing agricultural contributions. But also, some private firms have advanced pond technologies that could be implemented through a public-private partnership.”
“So how long will it take? So the Colorado River is buffered by the storage. And so I’ve heard that it will take about four years for that salinity to make it to Metropolitan. And I’ve heard that could result in an eight milligram per liter increase, on average, in the supplies that we deliver through the Colorado River Aqueduct.”
QUESTION: Is there a plan to divert GWRS water to the Santiago Creek basins in the future?
Greg Woodside: “That’s something that we’re currently assessing, and the plumbing is pretty straightforward to do that. We’re working through what permit modifications we would need from the regional board and other planning activities. But that is something that we’re looking at very carefully right now. So that would be for recharge of GWRS water and into what we call the Santiago basins, which are on the east side.”
QUESTION: Have you been monitoring changes in TDS from the early phases of the mid basin injection project?
Greg Woodside: “We have. That project is relatively new, so we don’t have as much data. I don’t have that available to present, but we have a series of monitoring wells around the mid basin injection wells, and we have been seeing changes in groundwater quality due to the injection.”
QUESTION: How do you foresee the implementation of further discharge permitting affecting the use of technologies such as industrial RO?
Mark Norton: “I’m a little bit less familiar with the permits associated with the industrial RO. But I think with any advanced technologies, there’ll be a need for brine disposal. And we do have a compliance plan associated with the brine pipeline that we work with the regional board on to ensure that we’re still protecting groundwater resources, and so I think it’s just going to continue to show that we are going to have that support of the regional board to encourage that those new industries that need brine disposal take advantage of the brine line and discharge their excess brine flows to the brine line as needed.”
“Overall for the permitting, as I mentioned for it was more for the wastewater treatment plants, and I think the longer-term average will certainly be a benefit. It made sense to the staff as well. They have that flexibility; it is actually written into some permits up in the Yucaipa Valley watershed. They have that, but with improved technology, there is going to continue to be of value and need for brine disposal and use the brine line.”
