The Vanguard continues to await data from the city, regarding a critical question – what will happen to the water rates in the event that Measure I is defeated and we continue to rely on groundwater?In his column on Tuesday, Bob Dunning reprints an email communication from someone he calls his friend “Bill” at Comcast.net.
He quotes “Bill” as saying, ” ‘According to city numbers, rates would increase by 50 percent over the next five years without the surface water project on the books.’ ” Mr. Dunning then comments, “Indeed, that sounds accurate from everything I’ve heard and studied …”
That 50 percent is probably a low-end estimate, and the city, as noted, has not yet presented the Vanguard with a revenue comparison for project and no-project alternatives.
Mr. Dunning continues quoting from “Bill”: ” ‘If I were to get a choice between a 300 percent increase with construction of the project and a 50 percent increase without the project, why would I ever vote for the project?’ “
Mr. Dunning responds, “Apparently, according to the proponents, you need to do this so your grandchildren will have adequate water, even if none of them will ever be able to afford to live here … adds Bill: ‘I would gladly pay an additional 50 percent on my water bill to maintain the city’s water utility.’ “
Mr. Dunning then writes, “Based on the most recent poll results released by the Yes on I campaign, it appears I’m the only person in town who still drinks Davis water direct from the tap, so ‘bad taste’ is no longer a reason for a new project … we appear to currently have an adequate water supply to meet our needs and city growth will be minimal for the foreseeable future … add to that the fact the city’s revenue projections on the new project assume we will all cut back our water use by 25 percent, and it appears we’ll be awash in water for some time …”
There is one thing that the Vanguard completely agreed with: “Before we all vote, it would be good if the city – with complete neutrality – would publish rates, benefits and drawbacks of the proposed project along with rates, benefits and drawbacks of maintaining the current system.”
In response, Matt Williams sent the Vanguard and other media entities a comparison chart between the project and no-project alternative.
Mr. Williams notes that the “typical” single family residence that Mr. Dunning describes is paying $34 per month average, currently. That would go up to $111.24, in per month averages, by 2018 under Measure I. Without Measure I, he argues, the cost would be $84 per month by 2018, more than double what it is today, but $27 less than under Measure I.
The city has not verified these numbers, so we must urge caution here, but based on the numbers we have seen, we believe that figure is closer to accurate than the 50% rate increase.
But water rates are not the only factor here.
Mr. Williams argues that under the no-project option, beginning as soon as the summer of 2017, Davis will experience “brownouts” of water as the peak demand exceeds the supply.
He argues that there will be no “brownouts” from 2013 to 2016, 3 mgd (million gallons per day) “brownouts” from 2017 to 2019; 7 mgd “brownouts” in 2020; and 10 mgd (or more) “brownouts” from 2020 onward.
He notes that the chart from the Brown and Caldwell report suggests “”brownouts” are most likely to occur when you are standing in the shower in the morning.”
He argues that there will be no “brownout” risk in any year under the surface water project.
He further argues that the water pressure under the no-project alternative may present a risk for fighting fires. He writes, “Minimum pressures on a maximum day are lowest in the western area of the system with minimum pressures ranging from 29 to 40 psi [pounds per square inch] west of the Highway 113. These pressures do not meet the City’s desire to maintain 40 psi throughout the system. There are eight locations where the fire flow deficiency is 1,000 to 1,750 gpm [gallons per minute].”
There would be no water pressure deficiencies or fire flow deficiencies upon the approval of the surface water project, Mr. Williams claims.
The costs of the water rates do not include the cost of water softeners or bottled water. Under the no-project alternative, those usage levels will remain at the existing levels. For those who do not utilize either, that may not be a cost savings that will diminish the gap in costs. But for the typical family, it may.
Mr. Williams argues, under the surface water project alternative, neither water softeners nor bottle water will be needed due to reduced mineral content in the water. That claim may overstate the decline of usage of either. Moreover, there is no data that Mr. Williams provides to determine exactly how much a typical family spends on either of those remedies for mineralized water.
Mr. Williams argues that the project alternative will impact the wastewater costs, as well.
Under the no-project alternative, “Elevated levels of constituents (Se, Bo, EC, TDS) increase complexity of wastewater treatment plant, and likely increase its cost.”
However, with the surface water project he argues, “Reduced levels of constituents (Se, Bo, EC, TDS) decrease complexity of wastewater treatment plant, and likely decrease its cost.”
How much cost this would add? Again we do not know.
Finally we have the drinking water constituents. He writes, “Deep wells are assumed to require treatment in the next 20+ years as drinking water quality limits for various constituents are added or modified by the federal and state legislators, and regulatory agencies (USEPA and CDPH). The most likely constituents of concern are Arsenic and Chromium 6. USEPA [U.S. Environmental Protection Agency] has indicated that they are evaluating Arsenic health impacts in drinking water and have indicated that revisiting the current standard of 10 ug/L [microgram per litre] could occur in the future, with a likely new numerical standard of 5 uq/L. In addition, both CDPH [California Department of Health], USEPA, and federal/state legislators are evaluating establishing a drinking water standard for Chromium 6, which currently has a Public Health Goal (PHG) of 0.06 ug/L. There has been published discussion of reducing the PHG to 0.02 ug/L. It is anticipated that a drinking water standard could be set at 0.06 ug/L with a PHG of 0.02 ug/L.”
With the surface water project, “Arsenic and Chromium 6 levels in surface water are well below USEPA limits.”
The Vanguard is still looking to get data from the city as to the projected costs and needed revenues for both the surface water project and the no-project alternative. Our hope in presenting the opinion of Mr. Williams is to facilitate further discussion so that the voters can understand what the alternatives really are, in hopes that they can make an informed decision on the trade-offs between the project and the no-project alternatives.
—David M. Greenwald reporting
Do you ever get the feeling that the water project pushers are throwing everything including the kitchen sink at us? First it was all about water quality, then degrading wells, cost of maintaining current infrastructure, now it’s water pressure and brownouts. What’s next, sinkholes?
rusty49
Would you prefer not to take into account all the possible relevant factors in making a decision ?
No, Rusty, dust bowls. Seriously now, as with the Dunning column, there’s no mention in David’s piece of the pending regulatory fines. Are those not costs that should be factored into the “no project alternative”, sink holes or no sink holes?
-Michael Bisch
DT:
“No, Rusty, dust bowls.”
LOL, that threat is already owned by the climate alarmists.
rusty,
First, I’m not a water project pusher, simply a data and facts gatherer. I try and let the facts and data speak for themselves. Think of Joe Friday stepping through a [i]Dragnet[/i] episode.”
Second, the way David wrote the article presents some of the information as my personal arguments. In the case of the water pressure/fire hydrant data the quoted words are from the Water System Optimization Plan performed by a team from Kennedy-Jenks Consultants and Brown and Caldwell in 2010 which I was reading in order to gather the facts behind the $37 million of current system repair costs that Staff and Bartle Wells included in the calculations of the rates presented to the WAC and Council . . . and all of us when we get our Prop 218 Notice.
Third, why are these arguments only surfacing now? Blame Bob Dunning’s column in yesterday’s Enterprise. In that column Bob made the truly superb suggestion that [i]”Before we all vote, it would be good if the city — with complete neutrality — would publish rates, benefits and drawbacks of the proposed project along with rates, benefits and drawbacks of maintaining the current system…”[/i] My immediate reaction was, “What a great idea!” and put together a first-pass table that brought in all the information about both the Yes and No arguments.
I then sent that first-pass effort over to Bob via e-mail to get his feedback. His e-mail response was, [i]”Great stuff, but I strongly doubt many people will stop buying bottled water or unhook their water softeners no matter what happens. That’s a huge, unproven assumption. And for those of us who use neither, it makes no difference anyway. How come nobody in authority is talking about the pollution produced regularly by water softeners?”[/i]
Fourth, let me ask you what you would do when you read the following quotes in the Kennedy-Jenks assessment? Would you consider them meaningful data that should be shared?
[indent] [i]”Minimum pressures on a maximum day are lowest in the western area of the system with minimum pressures ranging from 29 to 40 psi west of the Highway 113. These pressures do not meet the City’s desire to maintain 40 psi throughout the system. There are eight locations where the fire flow deficiency is 1,000 to 1,750 gpm.” [/i] (on page ES-3 of the report — page 20 of the pdf)
[i]”The evaluation criteria states that pressures above 40 psi are desirable. Pressures range from 45 to 55 psi on the east side of the system and decrease to the west with minimum pressures ranging from 29 to 40 west of the Highway 113″[/i] (on page 4-5 of the report — page 56 of the pdf)
[i]”Minimum pressures on a maximum day are lowest in the western area of the system with minimum pressures ranging from 29 to 40 west of the Highway 113. These pressures do not meet the City’s desire to maintain 40 psi throughout the system.” [/i] (on page 4-13 of the report — page 66 of the pdf)
[i]Deep Well 28 is the least desirable of the deep wells because of declining production (dropped from1,000 gpm to 600 gpm), well efficiency and water quality concerns. The City will need to monitor the performance of this well and determine if rehabilitation is not successful when it should be re- placed. One alternative to compare with drilling a new deep well at 800 gpm is to consider exploring an intertie with UC Davis near the new University Village located just south of Russell Blvd. and west of Highway 113 to replace the 600 gpm supply.”[/i] (on page 5-34 of the report — page 110 of the pdf)
For those who are interested, here is what I sent to Bob Dunning
[IMG]http://i1104.photobucket.com/albums/h321/mwill47/ComparisonChartFirstPass_zps9e5630d7.jpg[/IMG]
rusty, you can find the Drinking Water Constituents language on page 5-34 of the Kennedy-Jenks assessment (page 110 of the pdf file)
The weblink for the assessment is [url]http://public-works.cityofdavis.org/Media/PublicWorks/Documents/PDF/PW/Water/Documents/Davis-Water-Distribution-System-Optimization-Plan-Report.pdf[/url]
Rusty: “[i]First it was all about water quality, then degrading wells, cost of maintaining current infrastructure, now it’s water pressure and brownouts. What’s next, sinkholes?[/i]”
None of this is new Rusty, many people have been talking about these issues, and presenting the data to back up their concerns, for a very long time. As for the sinkholes, Don Shor has been commenting on subsidence concerns for years.
We may have more details now than we did before, but the general story has been the same since we started down this road more that a decade ago. Unfortunately, some in town have chosen to be ignorant, rather than read the data and understand the consequences. Denying the data does not change the outcome, it just makes us look shortsighted and stupid when reality comes back and bites us all where it hurts the most.
In-home costs of the current well water go well beyond bottled water. The life of plumbing fixtures is greatly reduced with hard water. Water softeners can help, but you’re still going to be fixing and replacing water faucets and water heaters much sooner than otherwise.
Is there any way to come up with a dollar estimate of those costs Davis Enophile?
Matt: Nice chart!
Depending on the audience, I might change the order of these things.
Also, in terms of the average Joe perspective, I think plumbing, appliance and fixture damage from heavy mineral deposits is another consideration. I hear complaints about water spot stains, clogged plumbing and deposit-damaged appliances all the time. These are the residents that don’t use a water softener. So, what is the family cost of having to replace a water heater or dishwasher more frequently because of mineral deposit build-up? And, if a family has a water softener, what about the cost for maintaining and replacing that appliance and the cost of salt?
I don’t want to pay more for anything… especially for government-provided services. However, I am fine paying more for commensurate added value. It is the added value provided by surface water compared to our well water that makes me a strong Yes on Measure I supporter. I think most other voters will be convinced with a similar consideration.
Now… if we only would take that same value-added approach with our education system when asking residents to pay more… sigh.
[i]The costs of the water rates do not include the cost of water softeners or bottled water. Under the no-project alternative, those usage levels will remain at the existing levels. For those who do not utilize either, that may not be a cost savings that will diminish the gap in costs. But for the typical family, it may.[/i]
In Dixon, population ~16000, for water softeners:
Average [rock salt] sales per day were about 1,130 pounds of sodium chloride, and 20 pounds/day potassium chloride. Local salt sales are shown to correspond to actual usage.
Mark West:
“As for the sinkholes, Don Shor has been commenting on subsidence concerns for years.”
And here I thought I was just kidding about the sinkholes.
From a 2011 discussion. Subsidence is occurring at 1/2 to 1″ per year due to pumping from the intermediate aquifers.
… the greatest area of subsidence is in the Yolo/Woodland/Davis/Zamora area. That is where the primary water used is groundwater (80% approx), not surface water. In the rest of Yolo County, farmers use primarily surface water (70% approx.). The biggest users in the groundwater area are the cities of Davis and Woodland, and UC Davis. That is where the land is sinking.
It is easy to conclude that the subsidence is likely caused by the overdrafting of groundwater in those areas.
In the rest of Yolo County, where surface water was brought in 1977 (Indian Valley), overdraft is not occurring and subsidence is not occurring.
The rate of subsidence in our sub-basin is high: up to an inch a year. That is how much the ground is sinking. When the ground sinks, it reduces the air space that water can fill. Ergo, it reduces the amount of future groundwater potentially available.
One possible solution is to artificially recharge the groundwater. Excess surface water could be pumped into the wells for storage. Discussing this option, and another, I have this from a previous link Sue Greenwald and I have both posted; it also confirms that we are overdrafting and that subsidence is a problem:
“These two activities might be used to help [b]reverse the heavy overdraft in the YZWD area, reduce subsidence there, improve recharge to the Yolo-Woodland-Zamora area of the aquifer, [/b]and more effectively use the groundwater in the western part of the County.”
Sacramento River water would be an excellent source of artificial recharge, allowing storage of high-quality water for use during drought years.
[b]Subsidence is a problem, and continuing to pump from the intermediate wells will increase the local subsidence caused by overdrafting in our region. [/b]
Trying to solve this by going to the deep wells creates its own set of problems.
Subsidence from increased usage of the deep wells.
From Pam Nieberg’s letter March 23 2005 appended as public comment to the UCD/City EIR:
“In addition, on page 11 – 16 it is stated that with deep aquifer wells, a pumping depression of about 80 feet is expected in the central-east Davis area. This could increase recharge flow from areas in the vicinity of the Sacramento River, which are expected to have higher levels of arsenic and manganese.”
Or as one particular blog participant might say: “so the Greenwald-Asmundson council poisoned our drinking water with arsenic and manganese! We need to audit them!”
Can’t find the doc yet that has info on the indirect cost of hard water. Will keep looking, what I remember is on average $20 per month was the cost.
According to one source, national average water softener salt use is about 60 lbs. per month. Typical price online is .15/lb. So for the water softener monthly salt cost is about $9. Potassium chloride pellets are much more expensive.
I’ve got a Kinetico system and salt runs me about $15 a year.
I find it rich that you are against the swp but you’re using salt and contributing to why we need the swp.
GI, but as you can see by my low salt use I’m actually a conservationist because I paid the extra to get a low salt electricity free system. You should be lauding me.
i don’t use any salt. that seems like a lot of salt since you can buy one package for like 69 cents. the combined use of the salts are a big reason why we are having to do this project.
You need to also amortize the cost of the water softener device and the installation costs. The Kinetico system is expensive. I think about $3500 installed. I think the resin tank lasts about 10 years with Davis water. They are about $1000 in parts and labor to replace I think. I have an idea because I just priced one to replace my salt guzzling Sears water softener.
So, figuring a 20-year life span with two resin tank replacement, you need to add another $22.92 per month.
Jeff, do you have any idea how many bags of rock salt you use each month?
GI, obviously you don’t use salt because you have no clue what you’re talking about. A bag of pellets runs about $5. You don’t use Mortons granules like you sprinkle on your eggs. I use 2 maybe 3 bags per year.
that’s right – i don’t know what i’m talking about with cost because i don’t dump salt into our wetlands.
And not all house water goes through the water softener. Kitchen faucet, refridgerator ice and drinking water and all outside use water run free of the system.
Don, all I know is that I would haul 200 lbs of expensive Morton compressed salt pellets from the grocery store (often they were out) and fill up the machine at home. Then it seemed like before I could count the days my wife was complaining about hard water again and I would go out to find an empty machine. I’m guessing it was about 100 lbs per month.
rusty49,
I have the kinetco system too – a very expensive water softener, but no electricity and very low maintenance.
I use a bag a month of salt for a 4 person household (no teenagers, so no long showers). The cheapest salt that I’ve found around Davis is $4 for a 40lb bag – about 10 cents a lb. If you are using only 4 bags of salt per year, you either are a very, very low water user or you aren’t keeping enough salt in the system. Or perhaps you’ve found a lower cost of salt than I have. Whatever the case, the cost of salt equipment and salt (or appliance and plumbing hardware costs if you don’t have a water softener) are factors that many Davisites need to consider when comparing alternatives to the surface water project.
That was when I had two teenage sons taking showers, and the machine was set to regenerate 3 times a week. Since then I have shut the thing off after thinking about how much salt I was pumping into the discharge. However, I need get a replacement if we are not going to surface water. I am doing some home renovation and want to get a tankless water heater. That and the newer dishwashers are known to have a much shorter lifespan with hard water… and Davis’s water is at the top of the hardness scale.
And the fancy shower glass is going to get trashed too if I don’t soften the water.
Jeff:
“The Kinetico system is expensive. I think about $3500 installed. I think the resin tank lasts about 10 years with Davis water.”
Jeff, I’ve had mine over 14 years and it’s still going strong. Never had a problem. I paid @ $1500 and that included a reverse osmosis system. Maybe the price has shot way up, that I don’t know.
[i]Subsidence is occurring at 1/2 to 1″ per year due to pumping from the intermediate aquifers[/i]
I wrote in another post about cracks forming in my 25-year old walls in West Davis. Somebody told me that there is a of that going around in the area because the city shut down one of the pumping stations located on Lake next to Covell. And because they shut it down, we are experiencing some uplift.
Which gets me to a question that I have to ask… if we have developed on subsided ground, then if we stop pumping, will it return to an un-subsided state and cause structure problems?
Jeff:
“Which gets me to a question that I have to ask… if we have developed on subsided ground, then if we stop pumping, will it return to an un-subsided state and cause structure problems?”
So we’re damned if we pump, and damned if we don’t.
Matt, to answer your question, I don’t know if there is a reasonable way to estimate those costs. Just figured it was worth mentioning.
[i]So we’re damned if we pump, and damned if we don’t. [/i]
Who said anything about the Monticello Dam? 😉
Possibly, I don’t know. I would like to hear from some civil engineer on the impacts of subsidence and uplift.
Well, I should have kept on reading. Others have provided quite a bit of information.
I have a tankless water heater. Its about 6 years old and will need replacing in another year or two. A water softener was servicing it for about 4 years (a kinetico). Then, as Jeff mentions, the kinetico tanks failed and sprung a leak. I ditched the whole thing because it seemed a rediculous expense to replace. But now its the water heater, and the plumber says, “why didn’t you replace the water softener…”
The expense of Davis hardwater goes well beyond the fee I pay to have it plumbed into my house.
[i]Jeff, I’ve had mine over 14 years and it’s still going strong. Never had a problem. I paid @ $1500 and that included a reverse osmosis system. Maybe the price has shot way up, that I don’t know.[/i]
Rusty – that $3500 cost included installation. Given inflation and the fact that the technology has changed and improved, doubling of the price is not a surprise.
So, for you the montly cost would be around $6.25 assuming a 20-year lifespan of the equipment ($1500 / 240 months). I assume you have never changed a resin tank?
[i]The expense of Davis hardwater goes well beyond the fee I pay to have it plumbed into my house. [/i]
One of the worst things that can happen, is if you have a pad and your water pressure drops because the copper pipes imbedded in the concrete are filled with hard water deposits (sort of like plaque in your arteries) and the plumber has to rip up your flooring and jack-hammer the pad to get to the pipes to replace them. One of my neighbors in a previous house had this problem, and he ended up having the plumbing re-routed up his walls and into his ceiling, where a joint then later failed and did another $7000 in water damage.
I agree 100% with you that there are a lot of other costs and cost risks associated with hard water… especially water as hard as Davis’s. It is that cost assessment that has me on the Vote Yes On Measure I support team.
JB: [i]I wrote in another post about cracks forming in my 25-year old walls in West Davis. Somebody told me that there is a of that going around in the area because the city shut down one of the pumping stations located on Lake next to Covell. And because they shut it down, we are experiencing some uplift.[/i]
I have a background in geology, but I don’t have a lot of background in groundwater processes. From what I understand, ground uplift from groundwater recharge on the scale you’re suggesting is unrealistic. Most of the ground expansion and contraction that takes place in west Davis is probably due to expandable clays. About 20 years ago, the parking lot at the Marketplace shopping center had to be repaved because expandable clays tore it up.
The footprint of a house’s foundation on top of a clayey substrate could lead to a differential expansion/contraction that can cause cracks a structure.
wdf1: thanks. What is perplexing is that my house is 25 years old and you would think that all the major cracking would have occured already. However, in the last 3-4 years, I have had new ones and in areas that had never cracked before. I was thinking it must be tree roots or something, but then this contractor friend of mine mentioned that the city shut down that pump and he knew of some of neighbors having a similar problem. Note that we are surrounded by drainage ponds too.
We are definitely on clay in that area.
I am working on a story about the subsidence and impacts. I was told though the rate of subsidence is only about one cm per year. But more on that shortly.
1.0 cm is about 0.4 inches. I’ve lived here over 20 years, that would be 8 inches. No wonder I’m so short.
David, the rate of 1/2″ to 1″ a year was from a report I have saved if you want it. It varies in the region, with the highest rates near Zamora. Jim Frame would know.
Since a centimeter is 0.39 inches, “only about one cm per year” isn’t insignificant nor that far from 1/2″ a year, particularly as pumping increased from the mid-level aquifers as Davis grew over the last decades. There are certainly areas of the same aquifer where it has been subsiding faster.
If we go to the deep aquifer, as we have done, the subsidence should diminish. The only question is what impact the vastly higher pumping on that aquifer will have. Between UCD and Davis increasing use of the deep aquifer something like five-fold, we will likely experience some effects.
David, great! Ask the question about what happens with our underground aquifer gets reloaded sans pumping. I have been researching that a bit, and hydrostatic uplift could be a real concern. I read that Venice and Paris are actually considering pumping water into the ground to reverse subsidence.
Also, what about basement and underground structures… would any of those be at risk of flooding if the water table rises? What about Aggie Stadium? Might the water polo team be able to play there at some point if we stop pumping and get a mega-wet winter?
I don’t know enough about these things, but it would seem that some due diligence is in order.
Here is a document which shows the pumping patterns in our mid-level aquifer:
[url]http://www.dcn.davis.ca.us/dcn/projects/conjunctiveuse/chapt3a.html#table4[/url]
Look at the sub-regions. Lower Cache-Putah is where Davis has traditionally pumped. And that is where subsidence is occurring.
[url]http://www.ycfcwcd.org/wmpdistrictwatersystem.html[/url]
“6. Subsidence
Land subsidence, due to groundwater extraction, is documented along the east side of Yolo County from Davis to an area east of Zamora. Subsidence between Zamora and Knights Landing is reportedly to be nearly five feet and in the vicinity of Davis and Woodland, two to three feet. There are two extensometers installed in Yolo County. One extensometer is located east of Zamora and the other is east of Woodland near the west levee of the Yolo Bypass. The latter was installed as part of the monitoring program negotiated as a condition of water transfers during the DWR water bank.”
For maps and more info, go to Yolo WCRA (yolowra.org) and look for the YOLO COUNTY INTEGRATED REGIONAL WATER MANAGEMENT PLAN. Map 2.7 shows the measured land subsidence in Yolo County.
I think 1 cm per year near Zamora is conservative, since quantifying this kind of movement with sparse the data sets in places like Zamora leaves a lot of room for error.
By comparison, we have plentiful data at continuously operating GPS stations. UCD1 is an antenna on top of the geology building that’s been in operation since the mid-1990s. As can be seen from the image below, the vertical displacement (bottom graph) has a distinct signal — there’s a fairly regular seasonal variation (soil saturation/dryout?), but also an unmistakable downward movement at the rate of about 1 cm per year.
[img]http://earthquake.usgs.gov/monitoring/gps/data/networks/SFBayArea/ucd1/itrf2008/ucd1.png[/img]
Hi Jim, I don’t know the data source for this map. It seems to show a range of subsidence rates around Yolo.
[img]http://davismerchants.org/water/Jan2005subsidenceYolo99to02.jpg[/img]
[url]http://davismerchants.org/water/Jan2005subsidenceYolo99to02.pdf[/url]
Definitely not looking good around Zamora!
Those contours are based on measurements taken in 1999 and 2002, i.e. only two data points at each of the stations shown as black triangles. The stations are about 7 to 10 km apart. Remeasurements in 2005 and 2008 allowed us to refine the contours, but the basic trends remain the same.
When we overlaid the contours on a water source image provided by DWR, the depressions lined up nicely with groundwater reliance.
Well-known example of ground subsidence due to excessive groundwater pumping in the south Central Valley:
[quote][img]http://water.usgs.gov/ogw/pubs/fs00165/Images/fig2.jpg[/img]Figure 2. Approximate location of maximum subsidence in the United States identified by research efforts of Dr. Joseph F. Poland (pictured). Signs on pole show approximate altitude of land surface in 1925, 1955, and 1977. The site is in the San Joaquin Valley southwest of Mendota, California. source ([url]http://water.usgs.gov/ogw/pubs/fs00165/[/url])[/quote]
Example ([url]http://museumca.org/creeks/z-subsidence.html[/url]) from Santa Clara Co.
I’d suggest that in many instances for California, ground subsidence is due mostly to agricultural usage of groundwater. Of course we’re all drinking from the same reservoirs.
In Yolo County the subsidence is occurring mostly in the sub-basins where groundwater usage is highest, which is where the cities and the university are. Most farmers have gone to surface water since Indian Valley was built.
Here is a more Davis specific graphic presented by Rob Beggs to the WAC on 3/24/2012 during his Deep Aquifer presentation. The graphic shows subsidence values from the Yolo Subsidence Network. If I remember correctly it is for the most recent ten year period. I’ll check with Rob to confirm.
[IMG]http://i1104.photobucket.com/albums/h321/mwill47/2012-03-24Item4-DeepAquiferPresentation_zps5f077a70.jpg[/IMG]
Jim Frame said . . .
[i]”Those contours are based on measurements taken in 1999 and 2002, i.e. only two data points at each of the stations shown as black triangles. The stations are about 7 to 10 km apart. Remeasurements in 2005 and 2008 allowed us to refine the contours, but the basic trends remain the same.
When we overlaid the contours on a water source image provided by DWR, the depressions lined up nicely with groundwater reliance.”[/i]
Jim, I didn’t see your post until after I posted Rob’s graphic. Can you comment on his graphic?
QUESTION TO EVERYONE . . .
It is clear that Subsidence should be added to the table. How would you word the No On measure I and Yes on Measure I entries in the table?
[IMG]http://i1104.photobucket.com/albums/h321/mwill47/ComparisonChartFirstPass_zps9e5630d7.jpg[/IMG]
SECOND QUESTION TO EVERYONE . . .
Based on the Water Softener Use/Cost discussions here, are there any suggested wording additions to the No On Measure I and Yes on Measure I entries in that row of the table?
[quote]Jim, I didn’t see your post until after I posted Rob’s graphic. Can you comment on his graphic? [/quote]
That appears to be from a 2006 report ([u]City of Davis/UC Davis Groundwater Management Plan[/u]) prepared by B&C and West Yost. It reflects data from the 1999, 2002 and 2005 observations of the Yolo Subsidence Network. Again, it’s in general agreement with the comprehensive adjustment of all the datasets (1999-2008) that we did for the WRA, though the subsidence indicated by the earlier results is slightly exaggerated due to the limits of the data, the use of updated geoid models for each of the individual observation epochs, and the improved understanding of what’s stable and what’s not that was obtained with each iteration of the measurements.
If no on i folks haven’t made any factual assertions, then “no response” is what I’d add to your table.