Green Valley Recharge Meeting
Meeting of January 23, 1006, 10:00 am
At University of Arizona Water Resources Research CenterNotes in blue are later additions.
Bill Lemman opened meeting: Thank all of you for being here. We hope to have a very lively discussion about the possibilities for recharging our aquifer. I would like to thank Professor Sprouse and the Water Resources Research Center for allowing us to use this room. We appreciate it very much. First, we are going to have a few remarks by Nancy Freeman. Eric Holler will make some comments We are going to have a conversation and some brainstorming about the issues that we are facing with our groundwater supply in Green Valley. I would like to have Nancy make some remarks.
Nancy Freeman: As many of you already know that the water companies in Green Valley and Sahuarita are not listed for assured water supply designation in the Tucson AMA. I determined to do something when I found out about this situation through the help of a phone call from a concerned water company employee. He told me I should be looking into the water depletion situation, that it was more important than the water pollution situation that I had been dealing with. When I investigated I did see that there was a problem. There is not adequate recharge in Green Valley aquifer, which is sustaining a depletion rate averaging two feet per year. And because of the CRD, it appears that nothing has to be done about it.
I feel that it is possible to recharge the aquifer with storm water. There were two years of flooding in 1982 and 1992. In those two years the aquifer did not go down—neither did it gain, but at least it remained level. So I read the 1999 feasibility study of bringing CAP into Sahuarita and Green Valley. At that time, it was decided that it was not economically feasible; therefore, the committee, which was formed to make this report, effectively disappeared and took no further action. Since Green Valley is unincorporated, there is no entity to take out a loan for the projected $50 million dollar pipeline, which does not include additional costs for filtering, delivery, maintenance and capital costs.
However, in that report there were mentioned other alternatives; such as, micro-basins, dry wells, reservoirs and river spreading. I started looking into these alternatives because if we are not going to have CAP water, we need to be getting a plan in place and start moving forward with the plan to recharge aquifer in Green Valley/Sahuarita area. I used to live in Chandler and I knew they had a lot small basins with dry wells to catch the storm water. I did go up there meet with the storm water manager. He was quite open and kind about giving me information. I do have their study about the efficiency of their system that recharges storm water, and at the same time use it to provide flood control. They have 4,000 wells scattered around town, most of them in microbasins around subdivisions, plus there are several major basins, which serve as a park when there is no rain. They have had some good results.
I think we need to look into this possibility of recharge of the aquifer in Green Valley. I do not know anything about water management, and I am not an engineer, so I have to depend on the experts. However, I’ve always used the motto in my life, “If you have a difficult job to do, give it to a lazy person, and they will find an easier way to do it.” So that is my goal. It seems to me that a project that will cost the community $50 million for just the first step of installing pipelines is the hard way to do it. So I think we should consider how these alternative methods can be used effectively?
In any event, we do need some long-range planning for recharge of our water supply in Green Valley. They are doing some recharge projects in Sierra Vista, so Eric Holler is going to say something about those projects. I am wondering if the ideas they are using over there can be used on the Santa Cruz. So definitely my overall goal is the sharing of information.
That is the goal for Groundwater Awareness League—we can be the instrument to compile and share information, so that every group does not have to start at Square One when having to deal with water depletion. We can compile feasible plans for alternative recharge methods to share with rural areas in Arizona, which do not have any possibility of access to CAP water at all. So we would like to hear any information you have that is relevant to the situation.
Bill Lemman: So we are asking people to share their opinions and information that they think is relevant to the situation, such as use of reservoirs, cistern systems, microbasins, dry wells. The residents of Green Valley do realize that the current system in place, an agency for contractor’s (CRD) that recharges in Marana on our behalf does not backup to give us any relief for our depletion in Green Valley without sufficient recharge.
Mark Cross: The hydrological part of the CAP feasibility report that Nancy mentioned was sponsored by ADWR. Errol Montgomery prepared the section on the hydrogeological conditions for recharge and the potential effect of recharge in that area. Malcolm Pirnie focused on the engineering aspect and the economics. I can briefly summarize the hydrological conditions. As Nancy mentioned groundwater has been over-pumped for decades and the groundwater is declining, we thought there were three possible methods of recharge:
First, would be infiltration using the natural stream channel of Santa Cruz River.
Second, would be constructing recharge basins, possibly in the flood plain of the Santa Cruz and infiltrating water in those basins. Those are virtually surface spreading methods. You spread the water on a land surface or a stream channel and it infiltrates and works its way down to the aquifer.
We also looked at the possibility of surface spreading on some of the alluvial fans along the mountain front, both on the Santa Rita side and the Sierrita mountain side. There’s a large number of small channels, tributaries of the Santa Cruz, many of them are quite small, but can be used in a way similar to what they are doing in the Sierra Vista area. They are constructing check dams, or at least proposing to construct check dams, to capture some of the storm water run-off that flows down from the mountain fronts towards the San Pedro River.
Now in the first two methods, which are in the river or in constructed basins, the source of water could be CAP water or treated effluent. The third method could also be CAP water or treated effluent, but could potentially enhance natural recharge and natural runoff. We did not look at the possibility of recharge wells because the quality of the water has to be so high, so that the wells don’t plug up. Therefore, we did not consider that option.
So to sum up, there are opportunities for recharging in that area, but you need a source of water, and the various options need to be studied in more detail to identify which option would have the most benefit. There were some recommendations in the report for a pilot study of one or more of those methods. Or if a source of water is available for some type of recharge, it would be advantageous to start a small project to collect data and as data is obtained to use that data to design a retention project. So that’s a brief overview of what we are looking at.
Right now there is not really a source of water other than a small amount of water from the Pima County wastewater treatment plant. So the big challenge is to get a good source of water.
In terms of natural run-off, recharge occurs naturally. Using USGS figures, we estimated that there is approximately 16,000 acre feet per year of natural recharge along the stream channel and mountain front between Pima Mine Road and Santa Cruz County line. Then back in the late 90’s there was an additional 7,000 acre feet per year of incidental recharge from FICO pecan groves. So the full amount of recharge, both natural and incidental, was estimated to be over 20,000 acre feet per year. There may be possibilities of enhancing natural storm flow run-off, but it’s not going to be a lot of bang for the buck. We can discuss this further, as Eric may have some information about Sierra Vista. There is already quite a bit of natural recharge and infiltration of storm water run off. It would quite an engineering challenge to capture large amounts of natural run-off and get it into the aquifer because the flows occur at such large rates. Personally, I’m not convinced that it would be cost effective.
Ken Seasholes: Perhaps I could broaden it out a bit at first. There are historic uses of water in the Green Valley/Sahuarita area that have been issued perpetual rights: the large mining operations and the FICO (pecan groves) irrigation. This non-municipal use has resulted in localized groundwater overdraft, there’s no question about that. While the groundwater declines vary across this area, it’s easy to talk in broad generalities, but we do need to be cognizant that there are variations even across relatively small portions of this entire aquifer management area, which is a much larger area than what we are talking about here.
The report that Mark was just summarizing the pieces that Error Montgomery did was funded basically by the AMA in large part because there is a recognition that CAP is a major important piece of the solution for this overdraft. It’s not the sole piece, but it’s a critical piece. The study provided a number of things including the baseline condition for folks to start thinking about how you could expand the CAP infrastructure further south, including what kinds of uses might be available and to think about what the impediments to doing the project are.
As pointed out in the study, what you really need to know about the major impediment is that it is uphill. When you go uphill, it cost a lot of money to move water because water is heavy. You have to pump it, in order to pump it you have to use a lot of electricity. Then there’s a big piece of costly infrastructure. That said, it’s a critical piece. I firmly believe and I think the State would support this position—that in the long term, it must be extended further south. Both because there are CAP sub-contractors that can take use of it. We recognize that this is a critical piece to achieve some measure of sustainability in that area.
Additionally, Mark mentioned water reuse, that’s a critical piece as well. Affluent has become a major part of how we are thinking about the future supply for the entire state obviously, and maximizing the use of effluent. Conservation is a piece of it, no question. Efforts in the GV area have been consistently well handled. We need to keep that emphasis. Conservation is a baseline piece.
The piece that Nancy is particularly interested in is enhancing storm water recharge and I think there are some possibilities of doing that, but it should be put in the broader context of importation of a surface water supply [CAP] (for which there are already existing legal rights), reuse of effluent, conservation, and storm water recharge enhancement. When we want to talk about these particular solutions, I do not want to lose sight of that bigger picture—of what a more comprehensive solution might look like.
Nancy Freeman: Tom Berry from Pima County Wastewater is here. Do you have the figure of the amount of wastewater effluent that is being recharged from the Green Valley?
Tom Berry: 2,100 acre feet
Ann Phillips: Are those evaporation ponds or recharge ponds by the treatment plant.
Tom Berry: They are not evaporation ponds, they are recharge ponds. However, most of the effluent—90% of it—goes to Quail Creek for landscaping.
Ken Seasholes: There are a couple of facilities now. There is also the Sahuarita recharge facility that is in the process. So the recharge of effluent has increased over the last years.
Eric Holler: Is that constructed recharge?
Martin Roush: Yes, plus the town of Sahuarita recovery well will reclaim system 250,000 gallons per day, increasing 7,000 gallons per month, which would be some 350 acre feet per year.
Bill Lemman: Now Eric will make a few comments about what they are doing in Sierra Vista.
Nancy Freeman: Can you give us some words of wisdom that will contribute to our sharing of information.
Eric Holler: We have provided some funding in Sierra Vista to do some effluent recharge in your typical basins. The jury is still out on whether recharge is taking place.
Recharge is not only getting the water to infiltrate at the ground, but through the vedose zone to the water table and then from the water table to be able to disperse out in a manner so that it won’t mound and cause problems at the surface.
So, long term infiltration, also known as recharge, is quite difficult to do. For our effluent recharge project in Sierra Vista, we are about to initiate an effort in modeling and monitoring to see whether that water is actually making it to the water table. We know there is a layer of clay in there that may be impeding the water from getting to the water table.
Nancy Freeman: What is the distance of surface to water table at this point?
Eric Holler: I don’t know exactly. But I think it’s about 300 feet.
Nancy Freeman: So that’s what we have in Green Valley, in general, about 300 feet.
Eric Holler: And just to add on to some of the things already said, and maybe not said, and maybe Ken could correct me. But when we talk about capturing rain water in the Sierra Vista area, Tom Whitmer, of ADWR reminds us that once the water hits the channel, the arroyo, are any of the main rivers, that water cannot be captured and retained. It can be detained in flood control basins, but you can’t recharge it. You can create things to slow the water down to help it infiltrate, but you can’t capture it and remove it off to a basin for example to recharge that water.
Ken Seasholes: A clarification on that. You can permit a recharge facility for the storage of surface water, but it must be recovered within 30 days of its being stored, so there is an on-going accounting issue and it also requires an appropriative right. You quickly start running into issues of the legal disconnect between surface water law and ground water law, as well as the ambiguities that flow from not having the surface water situation within this state fully adjudicated. If you are talking about small check-dams and things like that, it tends not to raise some these issues, but if you talk about large scale channelization and detention of natural flows in streams, a number of unresolved legal issues, as well as thorny legal issues are raised.
Nancy Freeman: So that would mean that if we are going to do anything in the Green Valley area, we would have to do it in places that are not on the rivers or washes that connect to the river. They have managed to do that in Chandler. I am hoping that the golf courses would be cooperative and would have low-lying areas that are not connected to channels. These areas could be a starting place. And even FICO may have some places because some of the drawdown on the FICO wells is greater than other areas in the region. So we have to be aware of this legal obstacle, and work within that framework—avoid channels and take the easy road.
Marie Light: There’s a lot of information that has been provided about the hydrology and some the legal rights associated with putting together a recharge project [in the river]. I can synthesize them from having had a number of years of experience with recharge projects. One of the things you look at is the depth of land surface down to the water flow. Apparently, you have 300 feet of surface that you can fill back up with whatever water you have available, whether it is storm water or effluent.
The hydrology is that you have coarse sediments along the stream bed that will be infiltrating that water. Definitely, Sierra Vista does have a different type of geology and there are impeding layers that will interfere with actually getting that water to a place that you can store it and recover it later. It is a different situation in Green Valley.
If you are looking at storing storm water, that is a very difficult process, because if you have ever seen water in the Santa Cruz it looks like chocolate milk, and that chocolate milk will immediately clog whatever surface you are recharging. That’s the nature of how the stream channels work, so a lot of natural recharge is based on the natural scarification along the river bed with the recharge of storm water. If you are going to have levies or something inside the channel, there’s a lot of maintenance associated with that, to maintain those continued high infiltration levels and that adds to the permitting issues and the maintenance issues.
So if you can do natural recharge that’s really the best, you can get a lot there without a lot of financial expenditures. You can put a basin to the side of the main channel—a couple of hundred feet away from the stream channel— or, as Mark has mentioned you go further up into the smaller valleys, you still have that water infiltrating down into a basin that you can get at. You can do that with both effluent and CAP water. You control the quality of the water depending on how you discharge it.
You do have the hydrogeology, so you need the water source. You can try different avenues and see which one works best. Tucson water did try to do some injection wells, and I advise to stay away from that. Basins and channels are good options. When you start to put water into the ground and you look at what groundwater rises you are going to get. What volumes of water are available now? How much is going out, versus how much is coming in? What are the CAP allocations in Green Valley?
Ken Seasholes: Community water has an allocation of 2,858 acre feet and Green Valley Water has an allocation of 1,900 acre feet.
Marie Light: So about 5,000 acre feet to recharge, which is a small amount of water.
Gary Sullivan: I’m sorry to interrupt, but that is water on paper. Right now we do not have CAP. CAP water is 1,000 feet downhill from us.
Marie Light: Yes, you will have to be able to transport that water from wherever your source is.
Ken Seasholes: Yes, that is a significant impediment. We are talking about recharge options, but there are also direct use options that are prevalent for users of CAP water. Green Valley area has legal rights to this valuable resource [5,000 af]. The critical piece that’s missing is the ability to move it further south to be able to take direct use of it. But I would not underestimate the value of having those contractual assets, a very valuable resource and an important part of the solution in Green Valley.
Marie Light: You have the right to it, but you do not have the infrastructure or the money to be able to use it. Those are definite impediments.
Frank Postillion: I will add that Chandler project capitalized on new water that was created because of the additional impermeable surfaces because of all the pavements and new construction that is going on in Chandler. They basically got more water to be able to recharge due to the development that is occurring.
In effect this is happening in Green Valley also because of the large amount of development there. The way that water is directed is that it goes into permitted detention/retention basins on subdivisions, then percolates slowly into channels, then it recharges into some fairly highly permeable channels in the Green Valley area. So in effect, you are getting more water than you did before—when it rains.
I think in the subdivisions the additional water that is detained and retained, that water can be recharged slowly into the subsurface aquifer. Then you do have additional recharge at the Green Valley wastewater and Sahuarita wastewater treatment facilities. So natural recharge does occur in Green Valley, so the biggest problem is that we have not been getting the rainfall that we need and that’s why you mentioned earlier that the water level has been dropping at a rate of two feet per year. If you go back and look at the earlier data in the mid-nineties and mid-eighties, the water levels came up significantly in that time period. Those natural channels, especially along the mountain fronts, were recharging at a very high rate.
However, there might be some help in micro-catchment, locally, at the house level. I’m not qualified in that area, but, Ann, you could speak to subject. You are the expert.
Ann Phillips: I would love to speak to that because often we look at these regional problems and think the solution is difficult, expensive, infrastructure driven, hard to maintain, and with an uncertain outcome. Actually, number one is conservation. In our community, we use 250 gallons per person per day and there has been no crack-down from ADWR on such high water use. There is a lot more potential for individual conservation.
Stopping or slowing down storm water in a wash, it works on many levels. If you put check dams, number one, you are providing erosion control. Number two, you are probably providing more water for riparian habitat. Number three, you are starting to create the slow movement of the water underground in the sediments that eventually makes it down to the main aquifer.
However, that recharge can also be augmented at the household level. All the rain water that flows from the houses and paved areas now goes into retention/detention basins pretty soon a clay layer forms and a bunch of tumbleweeds grow and mosquitoes breed in it. So you are talking about trying to get that little storm water allotment down through 300 feet to the aquifer. Logically, that is not likely to be recharging the aquifer if at all. [This would be different if a dry well were to be put in the basin?]
On the other hand, the houses that had all the groundwater deflected away from them are switching on their pumps and pulling water out of the water out of the ground. If you actually used that groundwater at the place that it originated—at the household—you have solved all the problems at once. You are leaving water in the aquifer.
The most efficient way to save water and to maintain your water level is to not take it out in the first place because trying to get it back in there is a huge, expensive engineering challenge. So just don’t take it out in the first place. By leaving more in the aquifer you will start to stabilize the water table. But we don’t know how stable the water table is because until we have the Water Budget. So a crucial piece of information is the Water Budget, how much water is being withdrawn and how much water is being recharged, between Pima Mine Road and the Pima County line. So we have heard a figure of how much is being recharged, so we have to know what the demand is. So what is the deficit you are trying to overcome here? So we need the ADWR model for the Tucson Active Management Area (AMA), which has not been done.
Nancy Freeman: I just talked to Phoenix ADWR and they say it’s done. It will be out within two weeks.
Ann Phillips: That’s good. It’s only been 10 years in the making. That tool will start to tell you what the localized water imbalance is. So I think there is much more potential for grassroots retention. I talked to planning and zoning in Sahuarita. If you were putting a rain harvesting requirement on the new Super-Walmart and the Ameritech homes. They resisted, they did not want to do that, so I doubt that did anything, if at all, it was superficial. But that is very doable.
The city of Tucson just adopted a water-harvesting guidance manual now. Every new commercial building, subdivision, public building and public driveway have to use rain water harvesting. So the technology is catching up real fast.
I think that before you talk about how many millions of dollars it is going to cost to extend the CAP pipe line down to Green Valley to bring in a bunch of poor quality water, with TDS of some seven to eight hundred. Why don’t we use rainwater that has a TDS of 50 to 100. It is high quality water and we treat it like a waste product. So that’s my thing, and it will always be, since it is logical.
Nancy Freeman: And there are conservation projects in Green Valley, such as switching to xeriscaping, and I am definitely pushing that. Frank from Flood Control mentioned that in the 1980’s and 90’s, there was not depletion in the aquifer. From the data from the Community Water wells, there was depletion, except for the two flood years. In those years, there was not a gain, but the water level did not go down its usual two feet.
Frank Postillion: From about 1978 to 1995, there was a wet period. Overall, regionally in the area, along the Santa Cruz River flood plain and the river bed and there was a significant recovery of water levels.
Mark Cross: We did find the same thing that Frank is stating. Overall in the Green Valley area water level stabilized and in some cases started rising through the middle part of the 80’s.
Gary Sullivan: How do you account for this difference?
Mark Cross: As Frank pointed out, the total flow on the Santa Cruz was 300 to 400 percent higher than normal for several years it was significantly higher. There was the big flood in 1983. You had perennial flow in 83 and 84 that lasted for 5 or 6 months so it made a big difference.
Ken Seasholes: In the Green Valley area, in general, there is an average of 59,000 acre feet of use. So even though there are these periods where there a greater amount of natural recharge tied to weather, there are historic large-scale groundwater declines. There is little doubt that there will continue to be an over-draft situation in the area. The largest users being the mining and agriculture users in the area. [In the late 1960’s, FICO filed a law suit against the mining operations for overdraft of the water supply in the area. That suit expanded and was finally ended in 1976. So the overdraft situation does go back historically. Further, the Anaconda Twin Buttes mining operation closed down in 1985 due to the drop in uranium prices, so that would have contributed to the stabilization and possible rise in water levels also.]
While we recognize the fluctuation through time, there is a little doubt that there is a net overdraft and has been a net overdraft. In terms of reflecting forward, one thing about the modeling effort is the challenge when you projecting forward a large unknown variable is, in fact, the long term usage of these non-municipal users.
You can take very divergent views about how long to expect the agricultural use relative to development. How much of the development takes place within the areas that are currently irrigated. While the mining district goes through the long-term cycles related to the cost as well as issues that are not related to water, in terms difficulty of running a mining operation in close proximity to a population center.
While it’s important to be able to project forward to try to figure out what we are up against in terms of the water budget, the uncertainties are quite large in terms of the projected use.
Nancy Freeman: In regard to the fact that we do have a river bed that does seem to recharge at a good rate when there is plenty of water there, it seems it would make it advantageous to slow the water down on the river bed, so that it is more likely to soak in and recharge. FICO does have some rights to some surface water in that area, so they would qualify to be able to do something on the river bed.
The big question is why can’t the public have surface water rights? Is it feasible for the water companies in the area to claim some surface water rights on behalf of the public, so that some projects can be done to slow the flow of the water, so it has a better chance of infiltrating into the groundwater? Another thing that we have to be aware of is a lot of these numbers were done in 1996 to 98, so eight to ten years have passed. Therefore, the groundwater has receded even further. The longer the wait, the longer distance there is to the water table.
In regard to the statement that debris clogs up dry wells when you are capturing storm water. In Chandler, the detention/retention basins are all grass lined, so it serves as a natural filter for the sediment. They are not having any problems at all with their dry wells clogging up. For the sake of the general public, a dry well is a casement that puts the water down in the ground some 100 ft. to enhance its percolation down into the water table, as opposed to an injector well. An injector well actually goes down to the groundwater level, so you have to have good quality water that you are injecting.
So if you catching storm water with a dry well then it percolates through layers of earth and the earth does act as a purification filter. That is what they are doing with CAP water up at Avra Valley. If we brought CAP water to Green Valley, we would have to have some sort of filtering system and apparently soil is, in fact, a decent filtration system, even for bacteria.
Now it was also mentioned that recharge basins are difficult to maintain and certainly they would be difficult to maintain with the high TDS levels of CAP water. In fact, more difficult, meaning that they would have to be emptied and cleaned regularly. Therefore. it seems logical that the better quality of storm water would require less maintenance.
Bill Dolan: In reference to Ann’s remarks. In about 1975, in Maricopa county, they passed a law that any commercial building must be retain 100% of rain fall on site. I don’t know if Walmart has any retention basins?
Ann Phillips: I’m sure they have some kind of retention basin. If you go to Meritage Homes, their basins are their flat-bottomed, with sharp sides, and they soak up pretty fast. I would like for somebody to prove that they are actually accomplishing any recharge.
Frank Postillion: It depends on the design of the basin. Flood Control District did a study of several detention/retention basins in Pima County. What we found was that it might not be really good for recharging large amounts of water. It will detain water and it may recharge water, but it can create a very lush riparian area, which can be used for many other uses, increasing habitat for birds and other animals. I think the people in Green Valley would like to see some natural areas restored.
So we did find that there is some incidental recharge occurring, but I won’t go into the details here. We are looking at the options and the possibility of retention/detention basins for multi-purpose recharge.
Marie Light: Frank is right. When you have these retention basins, you can create a nice environment for people to enjoy. The question is do you want to use that water for riparian habitat or do you want to preserve it for drinking water for the future. You have to decide what you are going to invest in--if the issue is a dropping water table and you are looking for the future of sustaining increasing population. That’s a management issue.
Frank Postillion: I have to address that; it does not have to be either/or. Multi-purpose recharge basins can not only recharge water, but can also maintain riparian habitat. There are places that are constructing these multipurpose facilities. We can look at some of the examples in California, you will see that they are utilizing retention basins. I think we are a little bit behind the time here in Arizona—maybe we will catch up.
Marie Light: Ann was mentioning that these basins do silt up. I have done some experiments of testing just how much silt does it take to seal off a bottom, or have a significant reduction of infiltration. It does not take a lot of silt to settle out. If you have something that comes in and scarified the bottom, then you have some good infiltration, or is the basin deep enough to infiltrate out through the sides. It depends on how you put together the project.
Martin Roush: The biggest problem is cleaning it out every five years or ten years.
In developments, the home owners association is responsible for cleaning out the basins. There are examples where they have really nice basins that captures the rain water, some of it recharged, some of it utilized by the vegetation, the mesquite trees and the native plants around there, and the rest of it goes into the channels that it would have originally flowed into. I think a lot of it is dependent on the rules (?) created for development. That is basically the Board of Supervisors and the planning and zoning commission to force these issues about maintenance of these retention basins.
Ann Phillips: I would like to point out, the reason the basins are there is not for recharge, it’s to control the flood peak. If all of that water comes rushing off that hardscape, the flow in the Santa Cruz would be greater than it would otherwise be. So they are supposed to detain and retain a certain amount off-site to control the flood peak, not to recharge, not to create habitat, but to control flooding.
What I do for Audubon is riparian restoration; I love riparian habitats. It’s a trade off between creating a new demand for that water. If you are going to take all the water in your subdivision and have riparian habitat, I would say great, but you are not going to end up drinking it.
How can all of these things be accomplished? I think working in the river, even creating a little more roughness and planting more vegetation in the Santa Cruz River. I am wondering how that be a natural retardant to the speed of the flow, so there’s a little bit more infiltration. I would like to see the hydrologist work on that problem. I’ve always been told, “Don’t put any trees in the river, it’s going to slow that water down and we will have more floods.” Okay, good, let’s slow it down.
I think there’s a possibility for a lot of creative solutions here. I did encourage Walmart and Meritage to put in more retention basins and neither one of them did it. The old Walmart was actually built for water-harvesting.
Martin Roush: I think that Oro Valley and Sahuarita tried retention and now everyone is going away from retention, because of HOA reasons, and mosquito reasons, and most of us do not believe that the smaller basins ever recharge the aquifer. The design originally stated retention/detention, and now we are saying the retention component is not doing any good, so we are moving away from that. It’s hard to get the HOA to maintain them, if not possible in some cases. Further, we are getting a lot of complaints about mosquitoes. [Notes from further conversation with Martin: Some of the basins seem to percolate and some don’t—there’s definitely different percolation rates. Dry wells won’t work because we have newly disturbed soils, so there is a lot of sediment movements. The dry wells would silt up. We have had to move 30 truck loads of sand off the road. Some twenty years from now the sediment will stabilize, so there is a life-cycle to the sediment problem.]
Are there any legal issues if the basins are for detention only?
Eric Holler: I don’t think there is any claim on that water. It is more of a natural, physical recharge. The reason why you get into the legal issues is the designation of assured water supply that someone wants to claim credit for.
Ken Seasholes: I won’t give a definitive answer on that narrow question. However, there’s a big difference if you are talking about recharge in terms of activities that contribute to the aquifer and permitted recharge where there is an off-setting credit generated and a lot of regulatory hurdles. So when we are talking about recharge, it is important to distinguish between those kinds activities that can help reduce groundwater pumping. So we are mixing some things together when we are talking about the details
Bill Lemman: Eric, do you want to mention anything more about Sierra Vista in this context.
Eric Holler: I don’t want to pile on any thing further about CAP water, but if you do recharge of CAP water, there is an endangered fish issue that needs to be addressed. The Bureau of Reclamation is having to mitigate from the introduction of non-native fish into central Arizona, so we are building fish barriers in the dry Santa Cruz. It happens in you have long periods of flows in the Santa Cruz River that would allow non-natives to migrate out of the CAP system and get into the waters of some of the native endangered species populations.
Marie Light: Where are putting those fish barriers?
Eric Holler: Right now we are looking into putting one barrier south of Pima Mine Road in the vicinity of FICO.
Unknown??: Is that because of the recharging in the Pima Mine Road project?
Eric Holler: We have decided that we need to some barriers in. The decision was made to put in two, you put in a pair so you can manage the space between the barriers, so the decision was made to put two in somewhere south of Pima Mine Road. They are basically drop-structures, that won’t allow fish to jump over and swim upstream.
Nancy Freeman: That sounds like what we need—that could serve our purpose.
Eric Holler: If they are placed the barriers at Pima Mine Road that means that any point upstream from that point on the Santa Cruz would entail more concentration with Fish and Wildlife Service and the construction of additional fish barriers.
Nancy Freeman: Maybe we can use fish barriers as the excuse to put some dikes across the Santa Cruz to slow the flow down.
Eric Holler: Just to add a thought about CAP water use. It costs a lot of money, but that money is relative. I think Ken hit the nail on the head when he said it is a very valuable resource. As a part of what we are doing down in the Sierra Vista area, we are looking at augmentation alternatives. One of those is looking at bringing CAP water from Tucson area to Fort Huachuca.
Unknown??: Can you route it through Green Valley?
Nancy Freeman: Right. Fort Huachuca has Federal money, so it’s a lot wealthier than Green Valley.
Eric Holler: The alignment of the routing goes down to Sahuarita Road then it heads east to 83 then jogs north on 83 and picks up the freeway and heads toward Benson. The point is there are others who are looking at CAP water as far south as Sierra Vista because it is worth it.
Is it worth it for folks to double their water bills in order to have a sustainable source? That’s a policy question that has to be answered. I am just telling you that others have made the decision already and have decided that it is worth spending the money to do that. In the future, you will think that a hundred dollars an acre foot for water is cheap. And if you could get water at that cost, you would grab it. You are looking at thousands of dollars per acre foot in California and glad to have it. So I wouldn’t discount the fact that CAP water is expensive, as something that would prevent you from getting it down there.
It might be a piece to the puzzle, these problems are not a single solution type thing. It takes many smaller pieces to make it up. What Ann indicated about retaining water that falls on residential areas and commercial areas, that’s a piece to the puzzle. It’s not the whole picture, but it’s an essential piece. Working in unison is how you are going to solve the problem, and working on many parallel solutions is the way to go.
Ann Phillips: We should mention that although you call CAP a sustainable, renewable water supply, but estimates of shortage on the Colorado River is thirty years out of the next one hundred.
Eric Holler: Since you brought it up, let me expound on that a little. In Sierra Vista, the CAP has been called the bank without any money in it. While it is true that there are going to be shortages on the Colorado, that’s almost for certain, unless it starts raining. But even so, the CAP water is divided up into levels of reliability. The Native American water and the municipal water have the highest priority. Models trying to figure out if there is going to be shortages of that high priority water show that is almost certain to be there most of the time. The probability of not having that amount of water available is quite small. There always going to be some water there.
The second aspect of this is—it’s been almost five years ago—since someone in Oro Valley asked me that very same question. My response was “Absolutely those shortages are occurring and that’s why folks in southern Arizona need to react right now. What we are doing by not acting now is we are foregoing the water that we could have been putting in the ground. We have some 250,000 acre feet of CAP water being brought into southern Arizona [annually]. Had we been putting all of it into the ground some place. Just do the math: ten years time 250,000 acre feet of water, 2 ½ million acre feet of water in the ground some place. We have taken the low lying fruit—the projects that are easy to do--by building recharge in the Tucson Basin in the Marana area in the lower Santa Cruz. That’s great. I commend Tucson Water because they had the foresight to build a project like Pima Mine Road up-gradient of the Tucson Basin. Yes, it was more costly and more difficult to do, but that’s where you want to put the water. Not in Marana, where it is going to flow out of the Basin.
So I say, act now. Some of the water is always going to be available. Yes, there are going to be periods of shortage that are going to effect agriculture, and incentive water. But acting now and doing the project now to getting water in the ground is the way to defray that.
Ken Seasholes: I think it is critical that people understand too that the State of Arizona through the Arizona Water Banking Authority has been storing water for that precise purpose. The Tucson AMA has over quarter of a million acre feet of water stored; totally stored over two million acre feet at a time. Precisely, at a time that M & I contracts cut back, not entirely, but reduction in storage. So the state has been forward-looking in that part of your property taxes are paying for that storage program.
There’s no question that shortages have to be factored into the operation of the system, but I can promise the folks in Green Valley that if the fish barriers go in too far north, and we sit idle and do not use the CAP allocations available and the additional GWRD services* that would be moved further south if there were [recharge] facilities available there, you will come to regret not having made those investments. [*presently, four subdivisions equals about 600 af.]
Because the water providers in Green Valley area do not have designation for assured supply for their entire service area, all the new developments since 1996 have to offset the majority of their usage with recharge within the Tucson AMA. So there are supplies being recharged by the Central Arizona Groundwater Replenishment District to offset those. As we pointed out, it does not directly benefit your subdivisions at this point. The GRD is operated by the CAP Board has a standing policy to try to recharge that water in as close a proximity to the demand as possible. If there were recharge facilities further south, this would be an additional supply above and beyond the allocations available, which would make that pie even larger.
Nancy Freeman: In the meantime, in regard to retention/detention basins in and around the subdivisions around subdivisions. Acknowledging that we do not have a way for subdivisions to recharge the mandated amount of water in the Green Valley area, it seems to me an idea that we could be looking at is: should those the new HOA’s actually have dry wells in their retention/detention basins, that is going to enhance the possibility of infiltration into ground water and in some ways—without too much redtape of permitting--offset the amount of CAP water that has to be recharged on the subdivisions behalf ten miles down stream from us. In other words, the money that they are paying for that recharge could go for dry wells. We would have to work with this through the County, the Board of Supervisors, but Sahuarita would not have to. [But an issue would be finding areas of good permeability that would not silt up.]
In Chandler, all the water has to be drained from the basins in 36 hours, so you do not have the opportunity for mosquitoes to breed. What do you do if it doesn’t drain in that time? You put in another dry well to siphon it off quicker until you reach the requirement of 36 hours. If you look around Chandler and you see the microbasins you have there, it really enhances the beauty of the area, making it one of the most beautiful areas in Arizona. So I feel it is an idea that we should look at.
Bill Dolan: I understand what you are talking about, and you do have good ideas. I want to ask: How long can we sustain the rate of development? Isn’t the water going to run out at some point? Can we continue to build?
Eric Holler: Dr. Herman Bower does a calculation that indicates that we can have about 17 million people in Arizona. That means very drop of water would going to human consumption. That might happen, and that could be, but if it does, I wouldn’t want to live here.
Bill Lemman: Can CAP water be used for mining?
Ken Seasholes: Yes, in fact, ASARCO has the ability to take up to 10,000 acre feet, and have infrastructures designed to do use 5,000.
Keep in mind that development is the best help to get CAP further south or up-gradient. There is a possibility that should a development come with CAP allocations, they will build CAP closer to Community Water Company in Green Valley, and even the Sierra Vista project will help some. [Are there CAP allocations actually available?]
We started this discussion talking about the 1999 study. There is renewed interest among Green Valley Providers about CAP use. It is being looked at actively. What Eric points out, and I would reinforce, there’s a lot of timing issues. These things are expensive and they are not the entire solution, but they are a substantial part of the solution. The cost of not bringing these supplies into an area that may be limited in its future ability to develop. The State of Arizona and the Tucson AMA does put significant requirements in order to demonstrate that you have a sufficient amount of water.
You can rely on groundwater, but if area that has substantial decline, it would be problematic to demonstrate that. Long term vision of a sustainable community in that part of the AMA does require a comprehensive solution. Delaying another half dozen years, may be even more costly.
Bill Lemman: Where do you see the impetus coming from most effectively?
Ken Seasholes: I think there is a broader recognition in the Tucson area that we have seen CAP go from something that had a very negative connotation, something that was costly to maintain you had to pay a fixed capital charge. There were folks wondering if it were worth hanging on to. The entire landscape, driven, I think in large part by the drought, time passage and increased growth, has changed that. People are recognizing that CAP is a valuable asset. The infrastructure and the allocations are relatively fixed. There are plenty of entities in Arizona and many more out outside the area that would be happy to use the water that is not being utilized.
Mark Cross??: What’s the prospects of water companies getting together trying to get Federal funds to bring that pipeline further south.
Eric Holler: There are no Federal funds per se. You can get some pretty good financing for those projects, but they all need to be paid back. Right now the rate for CAP repayment is around 3.25 per cent over 40 years.
Mark Cross??: Is there a possibility that Sahuarita could float some bonds?
Martin Roush: As I understand it, there’s no study of assured water supply done in that basin. The town of Sahuarita council has discussed and was directed to put in my budget money of some $45,000 for a study to look at our basin. Ken, is that something that we need to do now, since we are going to have the ADWR model?
Ken Seasholes: The region could benefit from a more intense look at hydrogeology, including modeling. There is no question that better data, more dynamic data is often helpful–but I would caution against studying the things to death and using that as an excuse not to move forward with some action. So somewhere between there, you recognize that, yes, we have to have a better sense of what is going on. The groundwater models developed for the AMA has been updated, and it is more refined than the previous model, but if you are looking at an even smaller area, you would want to do a refined analysis.
Frank Postillion: I think it has been studied to death and something has to be done to bring CAP in.
Nancy Freeman: Ken, on this list from the Tucson AMA there are other water companies in the AMA area that do not have assured water supply designation. Are they in the same situation that we are? Are their wells depleting also?
Ken Seasholes: The rules and program of the assured water supply rules are a technical piece. Let me generally explain what we are talking about. All these developments in the AMA must demonstrate that there is an assured water supply for that subdivision/s or there is a water provider that has demonstrated that for their entire service area. The largest providers in the Tucson AMA have demonstrated and continue to demonstrate that they have not only physical supply to meet the 100 year standard, but the bulk of that demand will be off-set through renewable supplies [CAP]. So Metro, Tucson, Oro Valley have the demonstrations that require a portfolio of supplies. It is a difficult thing to do, so CAP water, along with some groundwater use. So they have the ability to add subdivisions to their service, based on the demonstrations they have made for their entire service area. If you are served by a undesignated provider, in each subdivision, the developer, must demonstrate there’s a hundred year supply of water. For most of those subdivisions, they use ground water. There is a physical supply down to 1,000 feet that can meet the demand, taking into account other demands in the vicinity. Also, it does have to take into account that there are declining water levels.
Eric Holler: Could I interrupt here for a moment. That’s an important piece. When you speak of physically accessible water—that’s down to 1,000 feet. You are down to 300 feet* now. It’s State policy but 1,000 feet is going to cause tremendous problems. The water is there, it means you have “assured 100-year water supply”, but as an engineer, I know that when you pump at 1,000 feet it causes significant other problems. [*300 ft. below ground surface, but pumping is occurring at 700+ feet]
Bill Lemman: What is the difference in delivery costs of pumping at 1,000 feet and pumping CAP water?
Ken Seasholes: Yes, this is important piece, for before you reach 1,000 feet, you will have major infrastructure problems. There is no question that, while the 1,000 depth of groundwater limitation provides security for a physical supply, that it is not good public policy to de-water large parts of any area down from several hundred feet down to one thousand. The consumer protection piece of the assured water supply is based on there has to be at least some physical supply. We did have a track record in this state of land being sold with no sufficient water supply for the long term.
The water management piece is the piece that requires all of the subdivisions for the bulk of the water use on a per lot annual basis is off-set with the use of recharge of renewable supplies, principally CAP. It can happen anywhere in AMA. That spatial disconnect, which is what we are talking about here. You have an assured water supply in four subdivisions in Green Valley, but it is being recharged down-gradient at Pima Mine Road. The key to making this work is it does not happen perpetually. That we don’t stand in there for 90 years dithering over whether or not it was a good idea to move it south. The assured supply program in its broadest conception bides you time. It bides you time to extend infrastructure to where pumping is occurring--to remove that spatial distance. This needs to happen in the Green Valley area.
There does need to be enhanced efforts at conservation, storm water recharge, reuse of wastewater, and importation of CAP. There has to be a comprehensive solution, if there is going to be a real solution. The assured supply program is a piece of that gives that at least opportunity that there is water supply brought in to work with. This piece should not be diminished. It’s the most stringent water requirement anywhere in the western United States.
Eric Holler: Just to add to what Ken said, the Bureau of Reclamation works with local water providers trying to figure out the CAP water use question. Tucson Water, Metro Water, Oro Valley water, some of the bigger water companies around, all have in mind to use wet water. They are planning to use their CAP water where they pump it so they don’t get this spatial disconnect that Ken was talking about. They have made that commitment. It’s more expensive, but it is more sustainable once you do it. Then you have control over your water resource management future.
Marie Light: I was looking at the numbers. If you figure what is pumped per year (55-59,000) and what is recharged naturally [23,000]. You are looking at an over-draft of 30-40,000. So that’s your target if you want to get back in balance with those volumes of water, you have to find that much water to recharge. Or can someone pumping that water find another source of water? If Asarco uses 5,000 acre feet for their mining operations, that is an advantage to you.* People moved here because they thought it was a wonderful place to live, so you can’t just say, okay farmers and miners thank you very much, we would love to use that water now. [*This is not the case because Asarco usage was not figured into our numbers since it is sufficiently downhill from GV.]
Ann Phillips: I do sometimes wonder when somebody is going to slam the door. We all thought that the assured water supply was the way that was going to happen. Everyone was turning to ADWR and saying, I guess there must be assured water here because they are building here, so they must have one. People don’t realize that there would be subsidence if you did pump down to 1,000 feet. But the quality of water decreases as you get lower in the aquifer. Tucson Electric Power put in a 3,000 foot well and pulled up water that was over 150 ° F., which was full of metals. The deeper you go, the stranger the water quality gets.
Another thing that the assured water supply will allow, speaking of long term, you can drawdown the aquifer two feet per year and still have physical availability. That amount of drawdown is allowed. Is that correct?
The drawdown calculation is based on your starting point in your depth to groundwater and the bottom, either the bottom of the aquifer or 1,000 feet, and your surrounding users. The calculation of the net drawdown of all of those. I think you may be thinking of the recovery well decline criteria, which is a 4-foot decline. Two feet over a hundred years would be 200 feet of drawdown. You could have situations where a subdivision was allowed to be higher than that.
Ann Phillips: It seems to be there is something in the permit that you can put in a well if you only drawdown the water two feet per year. So if you are sitting next to a domestic well that’s one hundred feet in 50 years, those people just de-watered their well. There’s a lot of tragedy of the commons going on here.
The other thing, right now Tucson Water is going to the public, saying “Do you want to drink water of 700 to 800 Total Dissolved Solids, which means you can taste it, and it may not taste that too good to you—or do you want to do membrane filtration, which will cost multiple millions of dollars—and it will create a brine stream which you will have to evaporate in Avra Valley. So this is another challenge in dealing with the CAP supply. Also, if you recharge it in the aquifer, it is eventually going to come out in your wells, so there will be a gradual decrease in water quality over time. There’s a lot of nuances to this.
Personally, I am wondering if ADWR has ever said “no” to anyone statewide. “No, you do not have an assured water supply.” Yes, but the way that occurs is do “due diligence” before you buy a piece of property. If you were thinking about putting a development on a tract of land, you would assess the physical availability of water before you purchased that land. More often than not, we find even within the smaller subdivisions within an AMA, it may very well require changing the density or the overall demand of the subdivision in order to meet the standard. While there are some outright denials, the more common way would be that you would go and hire someone to figure out how much water is available, or you can rely on the designation of a water provider. There is no question that there are areas where you cannot currently demonstrate an assured supply and there are areas in order to demonstrate an assured supply outside of an AMA, you have to change the density.
Ken Seasholes: The further south you go, the more it costs. It’s further uphill. Just as it’s better more expensive, it’s more beneficial to go south.
Mark Cross: The further you go south, the depth to water is less, so there would be more constraints on how much water you could store.
Nancy Freeman: Yes, there is a different hydrology in the Canoa area, which must be taken into consideration. The water is not so deep, and it is closer to surface. I got a figure from the ADWR people who are working on the soon-to-be released modeling CD. In that area, the water is 300 to 400 feet deep, and 30 to 40 feet below surface, so it’s a pocket of a different hydrology because of a fault constriction, which causes the water to mound in that area.
??: Where are the mine supply wells?
Nancy Freeman: Their wells are in the Canoa area—that is upstream from municipal wells. They also told me that some of the PD wells are south of the fault and some are north of the fault. Also, PD is getting some data on the drawdown in their supply wells, and this will give us more information.
John Brack: Drawdown on supply wells as well as regional.
Dick Shuman: The best way to handle the Green Valley dilemma is not to take the water out. I would like to appoint myself water czar. Eventually, the pecans are going to disappear because it’s more profitable to build houses than grow pecans. So the pecan groves use about 45% of the water and the other 45% is used by the mines. I looked at that feasibility report and if you were to take CAP down south, paying $150 an acre foot, so it would not add more than $150 per acre foot, which roughly would be three million dollars a year. I also read in that report that the copper yield would drop less than1%, so that would be roughly three million dollars. So a cost of some six million dollars to take the CAP water to the Sierrita mine. So you could form a water district to offset some of the cost to the mines. [Cyprus Sierrita conducted a study in the mid 90's on using untreated CAP water for mining. First, the capital for the delivery system was prohibitive. In addition, the recovery for both copper and moly were adversely affected. The major impact was on the moly recovery, which makes sense in light of the fact that CAP water dissolved metal pipes in Tucson, plus the affect of high TDS. Therefore, PD/Cyprus declined any CAP allocations. Twin Buttes operation had allocations of 4,444 af, but they terminated that contract.]
Mark Cross: That would be an option because it is quite expensive to recharge an aquifer. Any time you can pump less groundwater. There’s in-lieu recharging as ADWR call it. If you can import surface water supplies and reduce pumping, it’s as if you are recharging the aquifer. So you don’t have the expense of physical recharging. Stop pumping water and groundwater starts rising.
Ken Seasholes: FICO was permitted as an in-lieu facility. I think the broader picture that we are beginning to touch on is once you start into the specific economics, politics, hydrology. Even starting to get into this would require a substantial update to the work that was done seven years ago. But there needs to be some momentum behind it. There are things being done, such as the fish barriers, such as others looking at CAP, water providers exploring the possibility of get designations of assured water supply. These things are coming together.
Nancy Freeman: If we are talking about spending millions of dollars, maybe Green Valley should buy the pecan groves and replace the pecans with mesquite trees and other native plants. That will stop pumping and provide a beautiful green belt that the pecan groves now provide in “green” valley. That would probably be the cheapest and easiest.
Unknown??: They are making too much money on the pecans.
Toops Culberson: I don’t think we are ready for that yet.
John Gay: You were talking about going down to 1,000 feet, something said about sub. Long Beach, California did not have any problem with water, but they pumped out all of the oil and Long Beach went down 19 feet. If you start pumping down deep here, you are going to have subsidence. You are going to have cracks in the roads, in the water lines. I don’t know how many of you have seen the floods, but I had just arrived here in 1965 and they had a flood just like in 1982. I was working at Banner Mine and I came down Pima Mine Road and the river was about a mile and a half wide when it floods. So it’s good to recharge then because there’s plenty of water. Then in 1982, by the Sahuarita Post Office it was like a lake. So you are talking about doing something in the river, you get such a huge amount of water coming down. Then I’m wondering if putting some of those millions of dollars into recharging of the headwaters, before it goes into Mexico and turns around to flow back toward here, whether recharge in that area will help us here.
Mark Cross: Possibly.
Carl Ortiz: Is it even physically feasible to recharge those large amounts of overdraft of 40,000 acre feet? You say there is a problem of natural recharge, what about recharge with CAP?
Mark Cross: Yes, there would be. We would have to identify the spots that would be most favorable from a hydrological standpoint because that affects the cost and efficiency. So if you have the best sites, it would be possible but expensive.
Marie Light: Think about it, just for buying 40,000 acre feet of water at cost $100 an acre feet, you are paying four million a year, just for the water. That doesn’t count managing it, or storing it, recovering it or filtering it.
Nancy Freeman: In the CAP feasibility report, there is a map of the best surface infiltration areas, so some of that work has been done. Plus I have been told that USGS could probably provide us some help on this stage of the project.
Also, I have available copies of the report of the Chandler recharge basins, for anyone who is interested. I will type the notes and get them out to everyone and then expect input from you what you would like to do to go to the next level. I appreciate everyone coming out. I think this really good that we all know the facts and figures and challenges because that is the first step. So I really appreciate it.
Bill Lemman: Anyone else have anything? We certainly appreciate your coming. You have been very generous with your time and your thoughts.