ADWR DEMONSTRATION PROJECT REPORT:

RESPONSE TO CONE OF DEPRESSION TEST COMMENTS

- San Pedro River Watershed -

In re The General Adjudication of the

Gila River System and Source

Arizona Department of Water Resources

May 2017

TABLE OF CONTENTS

1.0 INTRODUCTION ...... 1

2.0 BACKGROUND ...... 2

2.1 Stage 1: The Subflow Zone ...... 3 2.2 Stage 2: The Cone of Depression Test ...... 4 2.3 Stage 3: Impacts to the Subflow Zone ...... 5

3.0 CONE OF DEPRESSION TEST ...... 6

3.1 Variations in Models and Methodology ...... 6 3.2 Variations in Data ...... 8 3.3 Analysis of Variations in Models, Methodology and Data ...... 11

4.0 ISSUES IDENTIFIED BY THE SPECIAL MASTER ...... 12

4.1 Issue 1: The basis for adopting a conceptual model with hard rock barriers and a perennial stream instead of a model that provides for mountain front recharge .. 12 4.2 Issue 2: The reasons to use or not use the Jacob Non-Equilibrium Equation with an Image Well in addition to other methodologies...... 13 4.3 Issue 3: The basis for the use of the data and methodology selected to calculate pumping rates for irrigation and municipal wells...... 14 4.3.1 Irrigation Wells ...... 14 4.3.2 Municipal Wells ...... 15 4.4 Issue 4: The basis for the selection and calibration of the data to determine transmissivity values used in the modeling; ...... 16 4.5 Issue 5: The determination of the locations of the wells and the expected margin of error between the location of a well modelled in the Report and the physical location of the well determined using GIS coordinates...... 17

5.0 IMPORTANT POINTS ...... 18

6.0 RESPONSES TO SELECTED COMMENTS ...... 19

ADWR Demonstration Project Report Response to Cone of Depression Test Comments i May 2017 ACRONYMS

ADWR Arizona Department of Water Resources gpm gallons per minute GIS Geographic Information System HSR Hydrographic Survey Report IR irrigation MU municipal PWR Potential Water Right USGS United States Geological Survey WFR Watershed File Report

TABLES

Table 1 Changes in Calculated Drawdown Resulting from Variations in Models and Methodology Table 2 Changes in Calculated Drawdown Resulting from Variations in Input Parameters

FIGURES

Figure 1 Well Map No. 19: 111-23-025-W2: Changes in Calculated Drawdown Resulting from Variations in Input Parameters Figure 2 Well Map No. 29: 111-24-CBC-005-W1: Changes in Calculated Drawdown Resulting from Variations in Input Parameters Figure 3 Well Map No. 6: 111-23-DDA-016-W1: Changes in Calculated Drawdown Resulting from Variations in Input Parameters

APPENDICES

APPENDIX 1: Driller’s Log Program

APPENDIX 2: Cone of Depression Testing Methodology

ADWR Demonstration Project Report Response to Cone of Depression Test Comments ii May 2017 REFERENCES

ADWR, 1991. Hydrographic Survey Report for the San Pedro River Watershed.

ADWR, 2002. Subflow Technical Report San Pedro River Watershed.

ADWR, 2015. Initial Progress Report Concerning Implementation of Cone of Depression Tests.

ADWR, 2016. Third Progress Report Concerning Implementation of Cone of Depression Tests.

ESI, 2011. Environmental Simulations, Inc. user guide for AquiferWIN32© software.

Evans, L.G., and Haimson, J.S., 1982. SWAB/RASA Aquifer Parameter Study. Arizona Department of Water Resources, 23 p.

Ferris, J.G., Knowles, D.B., Brown, R.H., Stallman, R.W., 1962, Theory of Aquifer Tests: U.S. Geological Survey Water-Supply Paper 1536-E, 174 p.

Google. Technical Definition of “Accuracy”, https://www.google.com/?gws_rd=ssl#q=accuracy&spf=1494517658364. Accessed 10 May 2017.

Harbaugh, A.W., E. Banta, M. Hill, M. McDonald (2000). MODFLOW-2000, The U.S. Geological Survey Modular Ground-Water Flow Model – User Guide to the Observation, Sensitivity, and Parameter-Estimation Process and Three Post-Processing Programs: U.S. Geological Survey Open-File Report 00-184.

Johnson Screens, 2007. Groundwater and Wells (3rd ed.). New Brighton, MN: Johnson Screens, 812 p.

Kisser, K.G., and Haimson, 1981. Estimates of Aquifer Characteristics Using Driller’s Logs: Hydrology and Water Resources of the Southwest Arizona-Nevada Academy of Science Volume 11.

Leonard Rice Engineers, Inc., 2015. Review of the ADWR Initial Cone of Depression Test Progress Report.

Long, Mike and Niccoli, Mary Ann, 1981. 1979 Program for Determination of Transmissivity Values in the Salt River Valley Via Recovery Tests of 172 Irrigation

ADWR Demonstration Project Report Response to Cone of Depression Test Comments iii May 2017 Wells: Hydrology and Water Resources in Arizona and the Southwest, Arizona-Nevada Academy of Science (1981) p. 117-124.

Richard, S.M., Reynolds, S.J., Spencer, J.E., and Pearthree, P.A., 2000, Geologic Map of Arizona. Arizona Geological Survey Map-35, 1,000,000 map scale.

USGS, 2007. Ground-Water Flow Model of the Sierra Vista Subwatershed and Sonoran Portions of the Upper San Pedro Basin, Southeastern Arizona, United States, and Northern Sonora, Mexico. USGS Scientific Investigations Report 2006-5228.

ADWR Demonstration Project Report Response to Cone of Depression Test Comments iv May 2017 1.0 INTRODUCTION

As directed by the Special Master, the Arizona Department of Water Resources (ADWR) is filing its response to the parties’ objections and comments to ADWR’s Demonstration Project Report for the San Pedro River Watershed entitled “De Minimis Assessment & Cone of Depression Test Methodology” (ADWR’s Response). ADWR’s report was filed on January 27, 2017, the parties filed objections and comments on March 6, 2017, and the Special Master conducted a status conference on March 15, 2017.

By order dated April 6, 2017, the Special Master issued “Case Management Order Regarding Cone of Depression Test Methodology” (Special Master’s Order), in which the Special Master established certain deadlines for ADWR and the parties related to ADWR’s Cone of Depression Test. Id. ¶ at 4-5. The Special Master directed ADWR to respond to the parties’ objections and comments by May 12, 2017, including (but not limited to) a discussion of the following issues:

a. The basis for adopting a conceptual model with hard rock barriers and a perennial stream instead of a model that provides for mountain front recharge; b. The reasons to use or not use the Jacob Non-Equilibrium Equation with an Image Well in addition to other methodologies; c. The basis for the use of the data and methodology selected to calculate pumping rates for irrigation and municipal wells; d. The basis for the selection and calibration of the data to determine transmissivity values used in the modelling; and e. The determination of the location of a well modelled in [ADWR’s] Report and the physical location of the well determined using GIS coordinates.

Id. ¶ 2 at 3-4.

ADWR Demonstration Project Report Response to Cone of Depression Test Comments 1 May 2017 The issues listed by the Special Master are addressed below. Also presented below is background information and a sensitivity analysis of the AquiferWin32© model proposed by ADWR by comparing models, methodology and variations in data proposed by the parties. In addition, ADWR is providing responses to selected questions from the parties.

2.0 BACKGROUND

In order to identify wells located in the San Pedro River watershed that are subject to the adjudication court’s jurisdiction, the Arizona Supreme Court in Gila IV required ADWR to: (1) delineate the lateral extent of the subflow zone as defined in Judge Goodfarb’s adjudication court order filed on July 5, 1994 (1994 Order); and (2) develop a cone of depression test for wells located outside of the subflow zone.1 Certain requirements for delineating the subflow zone and developing the cone of depression test were further addressed by order of the adjudication court filed by Judge Ballinger on September 28, 2005 (2005 Order).

It appears to ADWR that the Special Master’s Order has taken these rulings into consideration and recognizes that additional tests will be required in the future to determine the extent to which a well’s pumping located outside of the subflow zone impacts subflow and streamflow inside of the subflow zone. The Special Master held that:

[ADWR’s] Cone of Depression Test is intended to be used for the purpose of identifying which wells located outside of the subflow zone will be included, under state law, within the adjudication and subject to the court’s jurisdiction. This determination does not preclude the use of the same or similar methodologies or variations thereof to be incorporated into future tests to be used in the next phase of this process.

1 In re the General Adjudication of All Rights to Use Water in the Gila River System and Source, 198 Ariz. 330, 344, ¶ 48, 9 P.3d 1069, 1084 (2000) (Gila IV). ADWR Demonstration Project Report Response to Cone of Depression Test Comments 2 May 2017 Special Master’s Order ¶ 1 at 3 (emphasis added). Accordingly, the Special Master directed the parties to file the following:

[P]roposals regarding procedures to establish an appropriate methodology required by the Gila IV Court that [the] Arizona Department of Water Resources may apply to determine and establish that a particular well is pumping subflow and the fraction of the discharge attributable to subflow. Parties shall also identify issues that should be resolved in connection with the approval of an appropriate test.

Special Master’s Order ¶ 4 at 4.

Consistent with the Special Master’s Order, it appears to ADWR that there are three stages that must be completed related to the identification of wells that are pumping subflow. The first two stages identify those wells that are subject to the jurisdiction of the adjudication court by means of delineating a subflow zone and applying an appropriate cone of depression test. ADWR believes that these stages are necessary to produce a tabulation of water rights within the watershed for purposes of a decree. The third stage involves an impact analysis of pumping from a well located outside of the subflow zone on subflow and streamflow inside of the subflow zone, which ADWR believes is necessary to properly administer and enforce the final decree. These three stages are discussed further below.

2.1 Stage 1: The Subflow Zone

As described in Gila IV, the lateral extent of the saturated floodplain Holocene alluvium (minus certain setbacks) on either side of a perennial or intermittent stream, comprises the subflow zone.2 By report dated 2015, ADWR presented maps delineating proposed subflow zones for the San Pedro River, the Babocomari River and Aravaipa Creek. This report was the last in a series of ADWR reports beginning in 2002 that were issued pursuant to Gila IV and orders of the adjudication court. The adjudication court

2 Gila IV, 198 Ariz. at 338, ¶ 18. ADWR Demonstration Project Report Response to Cone of Depression Test Comments 3 May 2017 conducted a four-day evidentiary hearing concerning ADWR’s 2015 report that concluded on September 3, 2015 after testimony by ADWR and the parties. The matter is still pending, and will be subject to review by the Arizona Supreme Court. Wells located within the subflow zone (as finally approved) are presumed to be withdrawing subflow as a matter of law, and the Potential Water Rights (PWRs)3 related to those wells would be subject to the adjudication court’s jurisdiction. To avoid having its PWR subject to the adjudication, the owner of a well mapped within the lateral limits of the adopted subflow zone would have the burden of establishing that the perforations of its well are below an impervious formation that would prevent its well from creating drawdown within the subflow zone. A well owner also may show that its well is in fact located outside the mapped lateral extent of the subflow zone.4

2.2 Stage 2: The Cone of Depression Test

Based on the Arizona Supreme Court’s opinion in Gila IV, the adjudication court in its

2005 Order directed ADWR to utilize a cone of depression test that can reasonably, reliably, economically, and expediently calculate the drawdown occurring at the subflow zone boundary resulting from a well located outside the subflow zone that is pumping under steady-state conditions. See 2005 Order at 24-25, 28-30. The adjudication court ruled that pumping from a well located outside of the subflow zone that has a drawdown at the subflow zone boundary, calculated by ADWR using steady-state modeling, that meets or exceeds 0.1 feet is subject to the jurisdiction of the adjudication court.5 Id. The

3 PWRs for well owners are included in the 1991 San Pedro River watershed hydrographic survey report (San Pedro I HSR). 4 Gila IV, 198 Ariz. at 343, ¶ 41. 5 Beyond use for jurisdictional purposes in the adjudications, the Cone of Depression Test adopted by the adjudication court (subject to review by the Arizona Supreme Court) arguably could potentially be used to determine whether water is being withdrawn or diverted within the Gila river maintenance area impact zone under A.R.S. § 45-2641(A)(3). In addition, the Cone of Depression Test could possibly be used to determine whether new water rights should be added to the final decree after it has been issued. ADWR Demonstration Project Report Response to Cone of Depression Test Comments 4 May 2017 PWR related to a well that satisfies this test would be subject to the adjudication to determine its nature, extent, and relative priority. As noted by Judge Goodfarb, ADWR believes that the total amount of water withdrawn from the well would be subject to the adjudication. 1994 Order at 62-63. A well owner may dispute ADWR’s determination by providing evidence that its well would not cause 0.1 feet of drawdown at the subflow zone boundary using steady-state modeling. In ADWR’s Demonstration Project Report, ADWR presented its Cone of Depression Test methodology based on Gila IV and the adjudication court’s 2005 Order using ADWR’s proposed subflow zone delineation.

2.3 Stage 3: Impacts to the Subflow Zone

To properly administer and enforce a decree that includes wells that have been determined to be pumping subflow by reason of their cones of depression, it will be necessary to determine the extent to which a well’s pumping impacts subflow and streamflow within the subflow zone by calculating the volume of subflow withdrawn from the subflow zone as a result of the well’s pumping. Note that a well’s pumping can induce water to leave the subflow zone without water from the subflow zone being pumped from the well.

ADWR believes that calculating subflow zone impacts will be more complex than conducting cone of depression testing and would need to address multiple scenarios. For example, a surface water diverter making a call on a junior appropriator may only be interested in impacts caused by wells occurring during the growing season. On the other hand, the holder of an instream flow water right likely would be interested in long term impacts. Also, determining impacts from a single well may be complicated by pumping from other wells with intersecting cones of depression and by climate. In addition, the impacts of a well’s pumping may be mitigated, for example by both incidental recharge such as that associated with irrigation uses, and intentional recharge, such as the effluent

ADWR Demonstration Project Report Response to Cone of Depression Test Comments 5 May 2017 recharge facility operated by the City of Sierra Vista which recharges a portion of the water pumped to serve the City’s population.

Because of the complexity of calculating subflow zone impacts, and the fact that a well owner can take steps to mitigate such impacts after a decree has been issued, ADWR believes that impact calculations should occur during the administration of the final decree. However, as indicated by the Special Master, discussion of the methods of calculating impacts can occur in parallel with the completion of the first two stages to identify wells that pump subflow. Special Master’s Order ¶ 4 at 4.

3.0 CONE OF DEPRESSION TEST

Based on the analysis in ADWR’s Demonstration Project Report, ADWR concluded that AquiferWin32© (ESI, 2011) used with the appropriate placement of image wells, as described in U.S. Geological Survey Water-Supply Paper 1536-E by Ferris, et al. (USGS, 1962), was a suitable means of conducting the Cone of Depression Test and would be utilized by ADWR. ADWR also concluded that the numerical model MODFLOW was suitable for conducting the Cone of Depression Test, but was not required.

3.1 Variations in Models and Methodology

In their objections and comments on the Cone of Depression Test methodology in the Demonstration Project Report, the parties’ experts proposed using MODFLOW, the Jacob Non-Equilibrium Equation and variations in recharge locations in the AquiferWin32© model used by ADWR. Table 1 compares the results of these proposals with the Demonstration Project results, as originally provided in Table 3-1 of the Demonstration Project Report.

Column 1 lists the well map number from the Demonstration Project Report, and Column 2 lists the well name. Columns 3 and 4 of Table 1 display the original MODFLOW and ADWR Demonstration Project Report Response to Cone of Depression Test Comments 6 May 2017 AquiferWin32© drawdown calculations at ADWR’s proposed subflow zone boundary from Table 3-1 of the Demonstration Project Report. Columns 5 through 8 present the drawdown calculations from other methods, described in the column header, proposed by the parties. Note that the green shade indicates that the results of MODFLOW and the alternative method concur as to whether the well is subject to the adjudication (in) or not subject to the adjudication (out), i.e. whether drawdown at ADWR’s proposed subflow zone boundary is equal to or greater than 0.1 foot or less than 0.1 foot. Yellow shading indicates that the alternative method calculated that the well would be out, while MODFLOW calculated that the well would be in. Blue shading denotes the opposite (the alternative method calculated that the well would be in, while MODFLOW calculated that the well would be out.).

As suggested by the parties’ experts, Column 5 displays the results using AquiferWin32© with a single image well to emulate recharge at the mountain front, while Column 6 displays the results using AquiferWin32© with a single image well to emulate recharge at the center of the subflow zone. Column 7 displays the results using the Jacob steady-state non-equilibrium equation proposed by Ford (Leonard Rice, 2015) with recharge at the mountain front, while Column 8 uses the same equation with recharge at the center of the subflow zone.

The methods used to produce the results in Columns 5 through 8 use the same transmissivity, pumping rate, and distance values utilized in the AquiferWin32© analysis described in the Demonstration Project Report. Note that the data is displayed by pumping rate ranked from lowest to highest (Column 9).

All the models and methods agree that wells with steady-state pumping of 4 gallons per minute (gpm) or less are not subject to the adjudication, regardless of whether recharge is at the mountain front or at the center of the subflow zone. With one exception,6 all the

6 Well Map No. 35 is unusually deep with a higher transmissivity. See Table 3-1 of the Demonstration Project Report. ADWR Demonstration Project Report Response to Cone of Depression Test Comments 7 May 2017 models and methods agree that wells with steady-state pumping of more than 20 gpm are subject to the adjudication, regardless of the modeled location of the recharge.

The remaining wells with steady-state pumping greater than 7.5 gpm and less than 20 gpm are discussed in Section 3.3 below.

3.2 Variations in Data

In addition to examining the variations due to model selection, recharge location and methodology, ADWR also examined how varying the data in the modeling used by ADWR would impact the results. Table 2 displays the results of this sensitivity analysis.

ADWR selected three wells with steady-state pumping rates of 4 gpm (Well Map No. 19), 11 gpm (Well Map No. 6), and 70 gpm (Well Map No. 29). As indicated in Table 1, for all three wells, the MODFLOW and AquiferWin32© calculations of the steady-state drawdown at ADWR’s proposed subflow zone boundary concurred as to whether the well was subject to the adjudication, or not.

Well Map No. 19 (4 gpm). The first row of well information in Table 2 is for Well Map No. 19 that has a steady-state pumping rate of 4 gpm.

The steady-state drawdown at ADWR’s proposed subflow zone boundary calculated using AquiferWin32© is 0.006 feet (Column 5), which indicates that this well is not subject to the adjudication. ADWR increased the pumping rate by 25% (Column 6), moved the well 500 feet closer to the subflow zone centerline (Column 8), decreased the transmissivity by an order of magnitude (Column 10), and increased the transmissivity by an order of magnitude (Column 11). ADWR also varied the location of the reference head in AquiferWin32©, moving it 10 miles further north from its original location 30 miles north of the pumping well (Column 12) and 10 miles south from its original location (Column 13). None of these changes altered the AquiferWin32© calculated drawdown so that it would equal or exceed 0.1 feet. ADWR Demonstration Project Report Response to Cone of Depression Test Comments 8 May 2017 Figure 1 graphically displays the color-coded 0.1 foot drawdown contours and cross sections of the cones of depression that result from the variations in data used in the AquiferWin32© calculations for Well Map No. 19. The map view7 in the upper left corner of Figure 1 shows the lateral extent of the 0.1 foot drawdown contours relative to ADWR’s proposed subflow zone. The red circle illustrates what happens to that contour when the pumping is increased by 25% (Column 6 of Table 2), the green circle illustrates what happens when the well is moved 500 feet closer to the subflow zone centerline (Column 8 of Table 2), and the blue contour line illustrates what happens when the transmissivity is decreased by an order of magnitude (Column 10 of Table 2). Other variations in the input parameters did not move the contour significantly

The black cone of depression cross section to the right of the map view shows the original calculations presented in the Demonstration Project Report. The six cone of depression cross sections beneath the map view represent the six variations in data presented in Table 2, color coded to the map view of the 0.1 foot drawdown contours.

Well Map No. 29 (70 gpm). The third row of well information in Table 2 is for Well Map No. 29 that has a steady-state pumping rate of 70 gpm. The steady-state drawdown at ADWR’s proposed subflow zone boundary calculated using AquiferWin32© is 1.550 feet (Column 5), which indicates that this well is subject to the adjudication. ADWR decreased the pumping rate by 25% (Column 7), moved the well 500 feet farther from the centerline of the subflow zone (Column 9), decreased the transmissivity by an order of magnitude (Column 10), and increased the transmissivity by an order of magnitude (Column 11). ADWR also varied the location of the reference head in AquiferWin32©, moving it 10 miles north (Column 12) and 10 miles south (Column 13). None of these changes altered the AquiferWin32© calculated drawdown so that it would be less than 0.1 feet.

7 The maps are produced incorporating distances from AquiferWin32© into ArcGIS. They are representations of the results and should not be relied upon for accurate measurements of the distance between the 0.1 foot contour and the proposed subflow zone boundary. ADWR Demonstration Project Report Response to Cone of Depression Test Comments 9 May 2017 Figure 2 is constructed identically to Figure 1 and displays the results for Well Map No. 29. The blue circle represents the 0.1 foot drawdown contour when the transmissivity has been increased by an order of magnitude. The 0.1 foot contours calculated for the remaining data variations are shown by the multi-colored straight line within the subflow zone which represents portions of much larger elliptically shaped contours that extend off the map view. Note that all the cone of depression cross sections except the light blue one (Transmissivity Increased by Order of Magnitude) show drawdowns of greater than one foot at the subflow zone boundary.

Well Map No. 6 (11 gpm). The second row of well information in Table 2 is for Well Map No. 6 that has a steady-state pumping rate of 11 gpm. The steady-state drawdown at ADWR’s proposed subflow zone boundary calculated using AquiferWin32© is 0.105 feet (Column 5), which indicates that the well is subject to the adjudication. ADWR decreased the pumping rate by 25% (Column 7), moved the well 500 feet farther from the centerline of the subflow zone (Column 9), decreased the transmissivity by an order of magnitude (Column 10), and increased the transmissivity by an order of magnitude (Column 11). ADWR also varied the location of the reference head in AquiferWin32©, moving it 10 miles north (Column 12) and 10 miles south (Column 13). The variations in pumping rate and transmissivity changed the AquiferWin32© calculated drawdown so that it would be less than 0.1 feet, which in turn changed the outcome from subject to the adjudication, to not subject to the adjudication. Similarly, moving the reference head closer to the pumping well also changed the outcome (Column 13). However, moving the well 500 feet further from the centerline of the subflow zone, decreasing the transmissivity and moving the reference head 10 miles north did not change the outcome.

Figure 3 is constructed identically to Figures 1 and 2 and displays the results for Well Map No. 6. The cone of depression cross sections show the drawdown at the subflow zone boundary varying above and below 0.1 feet. The 0.1 foot drawdown contours are present both inside and outside the subflow zone boundary.

ADWR Demonstration Project Report Response to Cone of Depression Test Comments 10 May 2017

3.3 Analysis of Variations in Models, Methodology and Data

Regarding the Cone of Depression Test, although the adjudication court agreed that ADWR should use a “focused and reasonable mechanism for obtaining highly reliable data which are used in setting model parameters,” the court also acknowledged that “numerous assumptions and considerable judgment” are required and that “in many cases, the test results will only provide a rough approximation of actual field conditions.” 2005 Order at 29-30. The adjudication court also noted that an “absolute accurate quantification is not possible.” Id. at 28.

With the adjudication court’s comments in mind, and the discussions above, ADWR believes that wells subjected to the Cone of Depression Test can be sorted into three subsets, which are discussed below.

Small volume wells. Certain small volume wells pump so little water that their calculated drawdown at the subflow zone boundary is less than 0.1 feet using any reasonable steady-state model and any reasonable estimates of their distances from the subflow zone boundary or their transmissivities. Even though the absolute accuracy of the data used in modeling these wells is not critical, ADWR will continue to collect data it considers to be accurate and reliable for these wells. ADWR believes that most of the wells in the San Pedro River watershed are small volume wells, withdrawing less than one, to perhaps up to three, acre-feet per year (equivalent to steady-state pumping rates of 0.62 to 1.86 gpm). See Table 1.

Large volume wells. Certain large volume wells pump so much water that their calculated drawdown at the subflow zone boundary is greater than 0.1 feet using any reasonable steady-state model and any reasonable estimates of their distances from the subflow zone boundary or their transmissivities. The absolute accuracy of the data used in modeling these wells is also not critical. As noted in the Demonstration Project

ADWR Demonstration Project Report Response to Cone of Depression Test Comments 11 May 2017 Report, the majority of wells pumping more than 50 acre-feet annually (equivalent to a steady-state pumping rate of 31 gpm) may fall into this category.

Medium volume wells: The calculated steady-state drawdown at the subflow zone boundary for these wells is generally near 0.1 feet. It is important that the estimates of distance to the subflow zone boundary and transmissivity be accurate. The method of modeling may influence whether these wells are subject to the adjudication, or not. Medium volume wells pump approximately three to 50 acre-feet per year (equivalent to a steady-state pumping rate of 1.86 to 31 gpm). ADWR plans to critically evaluate the pumping, distance, and transmissivity data used in the modelling for these wells, collect additional data if necessary, and afford the well owner an opportunity to provide input.

4.0 ISSUES IDENTIFIED BY THE SPECIAL MASTER

In paragraph 2 of the Special Master’s Order, the Special Master directed ADWR to address five issues related to the Cone of Depression Test. These issues are discussed below.

4.1 Issue 1: The basis for adopting a conceptual model with hard rock barriers and a perennial stream instead of a model that provides for mountain front recharge.

As described in Section 2.2 above, the Cone of Depression Test necessarily relies on the presence of a subflow zone. Subflow zones are only present adjacent to perennial and intermittent streams, and these streams also serve as a source of recharge to the pumping well. While it is true that the mountain front is a significant source of recharge in the Demonstration Project Area, it is also true that the San Pedro River can be a significant source of recharge along its losing reaches, during and after significant runoff events (floods), and in the northern portions of the watershed where the bounding mountains are ADWR Demonstration Project Report Response to Cone of Depression Test Comments 12 May 2017 lower in elevation and thus develop little or no snowpack. ADWR believes that locating the recharge along the centerline of the subflow zone8 is consistent with hydrologic reality. Though ADWR acknowledges that recharge does occur at the mountain front, it believes that placing recharge at the centerline of the subflow zone rather than the mountain front is the best solution for analytical modeling.

ADWR modeled the mountain front as a no-flow boundary during its AquiferWin32© modeling in an effort to be as consistent as possible with the MODFLOW model. ADWR continues to believe that this is the proper analytical modeling approach.

4.2 Issue 2: The reasons to use or not use the Jacob Non-Equilibrium Equation with an Image Well in addition to other methodologies.

ADWR utilized the Jacob Non-Equilibrium Equation as proposed by Ford (Leonard Rice, 2015) during the preparation of Table 1. The determinations of whether a well is subject to the adjudication or not compare reasonably well with the other methods shown in the table. ADWR is not familiar with this steady-state drawdown calculation method and has been unable to locate other uses of this method in the literature. ADWR would like to review previous uses of this method and associated literature before reaching a conclusion as to its applicability for cone of depression testing.

8 ADWR considers locating the recharge at the center of the subflow zone rather than at the actual mapped stream location to be a reasonable simplifying assumption for the Cone of Depression Test. If the recharge were placed at the stream location, the Cone of Depression Test results would change with time as the stream channel migrated and this could impact whether a well was subject to the adjudication. ADWR does not believe that the final decree should be subject to stream channel migration. ADWR Demonstration Project Report Response to Cone of Depression Test Comments 13 May 2017 4.3 Issue 3: The basis for the use of the data and methodology selected to calculate pumping rates for irrigation and municipal wells.

The steady-state pumping rate in gpm for all modeled wells is calculated by multiplying the annual volume withdrawn from that well in acre-feet by the conversion factor 0.62. For example, a well that pumped 10 acre-feet per year would have a steady-state pumping rate of 6.2 gpm.

4.3.1 Irrigation Wells

For irrigation wells described in the 1991 San Pedro River Watershed Hydrographic Survey Report (San Pedro I HSR), ADWR plans to calculate the annual volume withdrawn by:9

1. Determining the annual volume of the “maximum observed use” for each irrigation potential water right (PWR) served by wells described in the San Pedro I HSR. The maximum observed use is reported for each irrigation PWR in Volumes 3-6 (the subwatershed reports) of the San Pedro I HSR. The maximum observed use is not reported in Volume 7 (Zone 2 Well Reports), but the information is available in ADWRs records. The procedures for determining the maximum observed use are described in Appendix C of Volume 1 of the San Pedro I HSR. ADWR will follow the Appendix C procedures in cases where the maximum observed use for an irrigation PWR was not calculated prior to the publication of the San Pedro I HSR.

2. Using the San Pedro I HSR to determine which wells serve each irrigation PWR. If ADWR becomes aware through searches for other information, such as well logs, that a well listed in the San Pedro I HSR has been replaced, then ADWR will use the location of the new well in its analysis.

9 For future HSR investigations, ADWR will have access to additional data sources such as the USGS crop surveys. ADWR Demonstration Project Report Response to Cone of Depression Test Comments 14 May 2017 3. Determining the annual volume withdrawn from each well by evenly distributing the annual volume of each irrigation PWR to each of the wells that serve that PWR. For example, if an irrigation PWR were served by two wells, each of those wells would be assigned an annual volume withdrawn equal to half the annual volume of the irrigation PWR. There are cases where there are multiple irrigation PWRs served by multiple wells in different combinations. ADWR plans to construct a matrix to calculate the annual volume withdrawn from each well in such cases.

ADWR recognizes that many irrigation uses have changed or been discontinued since the publication of the 1991 San Pedro I HSR. ADWR can address these changes if so directed by the Special Master.

4.3.2 Municipal Wells

The San Pedro I HSR lists an “apparent annual volume used” and the wells serving each municipal PWR. ADWR will evenly distribute the apparent annual volume used to each well serving a municipal PWR to determine each well’s annual volume withdrawn. As noted above, if ADWR becomes aware that a well listed in the San Pedro I HSR has been replaced, then ADWR will use the location of the new well in its analysis. ADWR can use more recent pumping information if directed by the Special Master.

ADWR believes that its estimates of a well’s annual volume withdrawn will generally vary by less than 25% from what would have been measured at the well had it been metered. Estimates will be less reliable in more complex instances where there are multiple wells serving multiple PWRs.

ADWR Demonstration Project Report Response to Cone of Depression Test Comments 15 May 2017 4.4 Issue 4: The basis for the selection and calibration of the data to determine transmissivity values used in the modeling;

Transmissivity is the product of an aquifer’s hydraulic conductivity multiplied by its saturated thickness. AquiferWin32© requires inputs of hydraulic conductivity and saturated thickness to conduct its drawdown calculations.

Because of the paucity of aquifer pump testing data, ADWR primarily will rely on the Driller’s Log program (Kisser, K.G. and Haimson, 1981) to initially estimate the hydraulic conductivity of the aquifer near each well tested using the AquiferWin32© program. Lithologic descriptions reported in driller’s logs will be matched with standardized codes representing a group of drillers' terms with predetermined hydraulic conductivity values. For each well, a weighted average hydraulic conductivity based on the saturated thickness of each lithologic interval will be determined. Where possible, the driller’s log for the subject well will be evaluated. If the subject well does not have a log available, then wells near the subject well will be evaluated. The list of predetermined hydraulic conductivity values and the calculations used in the Driller’s Log Program are included in Appendix 1. ADWR’s Cone of Depression Test methodology is provided in Appendix 2.

For purposes of the Cone of Depression Test, the aquifer saturated thickness will be set to the largest measured saturated thickness for the well. ADWR will use the shallowest known water level measurement and the total depth of the well to calculate the saturated thickness of the well. If there are no available water level measurements or well depths, then ADWR will contact the well owner and attempt to collect such measurements.

For the Cone of Depression Test, ADWR believes it is appropriate to maximize the use of the data associated with the tested well. Thus, ADWR is only evaluating the saturated thickness of the aquifer penetrated by the well. This is consistent with ADWR’s practice of conducting well impact analyses within Active Management Areas. ADWR followed this practice during the Demonstration Project and found that there was significant

ADWR Demonstration Project Report Response to Cone of Depression Test Comments 16 May 2017 agreement in results between AquiferWin32© analyses with limited aquifer thickness and the MODFLOW calculations which utilized the complete thickness of the aquifer.

ADWR did not calibrate the results of its Driller’s Log Program hydraulic conductivity determinations with any other data. However, the hydraulic conductivity values used within the Driller’s Log Program were calibrated against aquifer test data collected in the Salt River Valley during 1979 (Evans and Haimson, 1982, Niccoli and Long, 1981).

It is important to note that ADWR will be utilizing the Driller’s Log program for the initial estimation of aquifer transmissivity values and will be flexible in evaluating additional information as it becomes available. Evaluating additional information from short term pump testing and other sources will be especially important for wells whose calculated drawdown at the subflow zone boundary is near 0.1 feet and for wells whose calculated initial transmissivity value differs significantly from surrounding wells.

4.5 Issue 5: The determination of the locations of the wells and the expected margin of error between the location of a well modelled in the Report and the physical location of the well determined using GIS coordinates.

All wells serving PWRs other than domestic and stockwatering were mapped in Volume 9 of the San Pedro I HSR. For the Demonstration Project, ADWR digitized these locations and incorporated them into its ArcGIS geodatabase. ADWR estimates that the ArcGIS mapped location based on the Volume 9 maps may differ from the actual location on the ground by +/- 200 feet.

ADWR then reviewed the imagery near the Volume 9 mapped location and attempted to locate the mapped well in the imagery. If it was located, ADWR then moved the mapped location to the imagery location and the uncertainty decreased to an estimated +/- 20 feet. Distances to boundaries calculated within ArcGIS would then also be +/- 20 feet. ADWR plans to follow these same procedures for future analyses.

ADWR Demonstration Project Report Response to Cone of Depression Test Comments 17 May 2017 ADWR will need to determine locations for domestic wells to conduct cone of depression testing because these wells were not mapped during the HSR investigations. ADWR suggests that wells serving de minimis domestic uses be excluded from analysis based on the findings of the Demonstration Project. ADWR can then locate only those domestic wells that serve multiple domestic uses, and which likely have annual volumes withdrawn of only a few acre-feet. As described in Section 3.3 above, it is likely that most of these wells would be small volume wells, and very few of these wells would be subject to the adjudication.

ADWR would locate the non-de minimis domestic wells using the San Pedro I HSR, well records, county assessor parcel information, and ArcGIS aerial/satellite imagery. ADWR estimates that these wells can be located to within +/- 200 feet, or in some cases to within +/- 20 feet. It is important to remember that, as described in Section 3.3, the cone of depression test is generally not sensitive to well location for small volume wells.

5.0 IMPORTANT POINTS

• Small volume wells (less than 2 gpm steady-state, approximately 3 acre-feet per year) have a cone of depression where the lateral extent of the 0.1 foot contour is generally measured in hundreds of feet. • Large volume wells (greater than 30 gpm steady-state, approximately 50 acre-feet per year) have a cone of depression where the lateral extent of the 0.1 foot contour may be measured in miles. • The accuracy of the data is most critical for medium volume wells and therefore most of ADWR’s efforts will be focused on these wells, by critically evaluating the modelling methodology and collecting additional data.

ADWR Demonstration Project Report Response to Cone of Depression Test Comments 18 May 2017 6.0 RESPONSES TO SELECTED COMMENTS

1. ADWR should use transient modeling rather than steady-state modeling because steady-state modeling does not accurately determine whether, when or to what extent a cone of depression may be affecting the subflow zone.

Judge Ballinger’s 2005 order states that “ADWR shall use a reasonably reliable steady state model for use in evaluating the effect of cones of depression.” 2005 Order at 42, ¶ 7. As directed by the adjudication court, ADWR’s proposed Cone of Depression Test is based on steady-state modeling. Moreover, based on the analyses described above and in the Demonstration Project Report, ADWR believes that steady state modeling is appropriate for conducting cone of depression testing.

2. ADWR should rely on numerical models such as MODFLOW because they are more accurate and reliable than analytical models such as Winflow.

Accuracy is defined as “the degree to which the result of a measurement, calculation, or specification conforms to the correct value or a standard.” (Google, accessed May 10, 2017). There is no correct value for the calculated drawdown at the subflow boundary resulting from the steady state pumping of a well. Nor will there ever be.

What does exist are various calculated drawdowns resulting from various models and equations using reasonable estimates of aquifer properties, pumping rates, and distances from boundaries (see Table 1). When the results of these models agree, it is reasonable to accept the results as valid. Where the results disagree, it is important to attempt to reduce the uncertainty in the data and consider the appropriateness of the assumptions inherent in the various models.

ADWR believes it has adequately demonstrated that the use of MODFLOW is not required to conduct the Cone of Depression Test. ADWR is also concerned that if a MODFLOW model were used to identify wells subject to the adjudication, that at ADWR Demonstration Project Report Response to Cone of Depression Test Comments 19 May 2017 some future time that model could be recalibrated, based on the addition of new data, and the new results then could change which wells would be subject to the adjudication. With analytical models on the other hand, new data will generally only affect a single well, and that single well will likely be the source of the new data.

3. Which MODFLOW package was used to represent the pumping wells (i.e., WEL, MNWI/2, or another MODFLOW package)?

The MODFLOW Well (WEL) package was used to represent the pumping wells.

4. How the model layers were selected for vertical placement of each pumping well?

All pumping was assigned to the uppermost active model layer for a given well. The uppermost active layer was identified for a given row and column using the IBOUND arrays in the MODFLOW Basic Package.

5. If a well's screened interval straddles one or more model layers, what criteria were used to select one layer for pumping? Was apportioning pumping between the model layers for wells that are screened in more than one layer tested (e.g., apportionment of pumping by relative layer transmissivity)?

A few tests were run with pumping apportioned vertically based on relative layer transmissivities, however in at least one of those tests a model cell went dry and the pumping assigned to that cell went un-simulated. Based on that result it was decided to assign all pumping to the uppermost active layer for a given well.

ADWR Demonstration Project Report Response to Cone of Depression Test Comments 20 May 2017 6. Was a model cell of the MODFLOW Model that had any portion of the proposed subflow zone used for the cone of depression analysis, no matter how small the area of overlap between the model cell and the proposed subflow zone?

None of the 41 wells tested were in a model cell that also included the subflow zone boundary. However, while conducting the generic test for de minimis well impacts, a domestic well was located in a model cell that included the subflow boundary along the Babocomari River in Layer 1 at Row 118 Col 131 (see page 32 of the Demonstration Project Report).

7. Why recharge was included in the MODFLOW model pre-development steady- state simulations but not considered in AquiferWin32 analyses?

ADWR used the published USGS Upper San Pedro Groundwater Flow Model, which included mountain front recharge and recharge of baseflow that was discharged along upstream reaches of the San Pedro River within the model area. The AquiferWin32© analyses incorporated recharge using image wells.

8. ADWR relies on creation of a series of "image wells" to "emulate the effects of impermeable 'hard rock' barriers and perennial streams such as the San Pedro River." ADWR Report at 29. ADWR concluded that eight image wells should be created for every actual well to be analyzed, without explaining how this elaborate process might affect the accuracy of each test.

ADWR referenced the U.S. Geological Survey Water-Supply Paper 1536-E, Theory of Aquifer Tests, (USGS, 1962) for the image well analysis. On page 156 of that report, under the section “Impermeable Barrier Parallel to a Perennial Stream,” the

ADWR Demonstration Project Report Response to Cone of Depression Test Comments 21 May 2017 deployment of image wells to emulate a discharging well between a perennial stream and parallel impermeable barrier is discussed. The layout of the image wells is displayed in Figure 42 of that report, which was incorporated as Figure 3-4 of the Demonstration Project Report. The San Pedro River, considered perennial for the purposes of the Cone of Depression Test, is bounded to the east and west by mountain ranges forming impermeable boundaries.

As stated in Water-Supply Paper 1536-E, a recharging image well placed the distance from the discharging well to the perennial stream (B) (see Figure 3-4 in the Demonstration Project Report), and a discharging image well placed the distance from the discharging well to the impermeable barrier (A) (Figure 3-4) are added in pairs until no drawdown occurs along the perennial stream or across the impermeable barrier. ADWR found during trial runs on multiple wells in the Demonstration Project area that although some drawdown was occurring across the impermeable barrier in some of the trial runs, the results were not improved by the addition of more than eight image wells to the model. ADWR believes the placement of the reference head on the perennial stream boundary prevented the model from reaching zero drawdown across the impermeable barrier. Mounding across the perennial boundary was minimized in the analyses.

ADWR’s use of image wells to emulate boundaries is a generally accepted practice. Water-Supply Paper 1536-E (USGS, 1962) is still cited in widely used reference books such as the third edition of “Groundwater & Wells” (Johnson Screens, 2007).

9. ADWR acknowledges that "the proper placement of the 'reference head' point is very important for steady-state calculations of drawdown using AquiferWin32,"

ADWR Demonstration Project Report Response to Cone of Depression Test Comments 22 May 2017 but it fails to explain the criteria it used to place the reference head for these tests at a location 30 miles away from the wells being analyzed or what effect that placement may have had on the accuracy of its calculations.

The original trial analyses for the Demonstration Project wells were conducted with a reference head 60 miles north of the 0,0 point used in the AquiferWin32© steady state model. Sensitivity tests were run on the 27 demonstration wells west of the San Pedro River, which included variations of aquifer top and aquifer bottom elevations, hydraulic conductivity, and distance to reference head. The results from those runs were compared to the results obtained from the MODFLOW analysis.

In the sensitivity test runs for reference head, the distances tested ranged from 1 mile to 120 miles north of the 0,0 point, and the resultant drawdown was compared to the drawdown obtained from the MODFLOW steady-state run. In addition to those steady-state runs, three wells west of the San Pedro River were selected for a transient analysis within AquiferWin32©, to determine a distance to the zero-drawdown point (obtained from the zero-drawdown contour line around the pumping well). Pumping from these three wells varied from 7.7 to 390.7 gpm and the time periods varied from 100 to 1000 years. The resulting distances to the zero-drawdown point varied from 3 to 37 miles. The zero-drawdown distances obtained from the three transient runs were then used to set the reference head distance in AquiferWin32© in a steady-state run for the corresponding demonstration well. The results were compared to the drawdown obtained from the MODFLOW steady-state run. Based on the analyses described above, ADWR determined that 30 miles was an acceptable distance to place the reference head from the center of the model.

ADWR conducted additional reference head sensitivity testing for this report (see Table 2) and believes that variations in the distance to the reference head have limited impact on the AquiferWin32© calculated drawdown results for small and large ADWR Demonstration Project Report Response to Cone of Depression Test Comments 23 May 2017 volume wells. The placement of the reference head can impact the results for medium volume wells, as can variations in transmissivity, distance to the subflow zone boundary, and steady-state pumping rate.

As shown in Table 2, moving the reference head further from the well being analyzed increases the calculated drawdown at the subflow zone boundary. Therefore, if placing the reference head 30 miles from a small volume well is too far, moving it closer will only decrease the calculated drawdown at the subflow zone boundary and not change the result that the small volume well is not subject to the adjudication. The reverse is true for large volume wells. If 30 miles is too close to place the reference head, moving it further away will only increase the calculated drawdown at the subflow zone boundary and not change the result that the large volume well is subject to the adjudication.

10. The Report should describe if the drawdown results were developed from graphical contours or exact locations along the sub flow zone boundary.

The AquiferWin32© program includes a “Line Calculation” tool, which will give the user the ability to calculate the drawdown at any point along the line (calculated at an interval set by the user). In each run, ADWR included a Line Calculation that began at the proposed subflow boundary and ended at the center of the well, along a straight line. After the simulation was run, a Line Calculation summary table provided the drawdown at each point along the line, at the designated interval. ADWR utilized the value at the start of the line, which was the drawdown at the proposed subflow zone boundary.

ADWR Demonstration Project Report Response to Cone of Depression Test Comments 24 May 2017

11. The figure on page 4 of Appendix B shows the no-flow boundary within the 0.11 foot drawdown contour around the pumping well, which indicates that the distances to the image wells are incorrect. The no-flow boundary should be centered between the two 0.11 foot drawdown contours.

ADWR checked the placement of the discharging well, the image recharge and discharging wells, and the impermeable and subflow boundaries and found there to be no errors in the locations of these elements in this analytical model run. As noted in the response to Question 8 above, ADWR believes that the placement of the reference head impacts the distribution of the drawdown contours across the no-flow boundary.

12. Based on the example in Appendix B, it appears the aquifer top elevation was set to the same elevation as the reference head; as such, AquiferWin32 could easily be simulating confined conditions (i.e., simulated head elevation above the input aquifer top elevation) in some locations, most notably at recharging image wells. This model construct may or may not have large impacts on the overall results, but it indicates a departure from the conceptual model being simulated using this method.

ADWR acknowledges the reference head elevation was set equal to the aquifer top elevation in the Demonstration Project AquiferWin32© analyses. However, ADWR has verified that the resulting drawdown at the proposed subflow zone boundary does not change if the aquifer top elevation is made higher than the reference head elevation. ADWR will correct this oversight and ensure that the aquifer top elevation is greater than the reference head elevation in future AquiferWin32© analyses.

ADWR Demonstration Project Report Response to Cone of Depression Test Comments 25 May 2017

13. ADWR would agree that analytical groundwater models are based on assumed hydrogeologic conditions and are not calibrated to historic or recent conditions, correct?

Analytic groundwater models utilize measured or estimated aquifer parameters such as hydraulic conductivity. Aquifer parameters can be calibrated to measured drawdowns in observation wells associated with a pumping well aquifer test. ADWR does not plan to attempt to calibrate the analytical model it proposes to use.

14. Does ADWR agree that in order to use WinFlow© for cone of depression testing, the Department's modeling staff would be required to individually parameterize each well (or each group of wells) to be tested?

Yes. ADWR would need to determine the distances to the subflow zone boundary, subflow zone centerline, and no-flow boundary; the steady state pumping rate of the well; the depth of the well; and the estimated hydraulic conductivity of the aquifer near the well.

15. If the decision is made to use WinFlow© for cone of depression testing for the thousands of wells in the San Pedro River watershed, how much ADWR modeling staff time does the Department estimate would be required to individually parameterize each well to be tested?

After its process has been optimized, ADWR estimates that it will be able to calculate drawdowns at the subflow zone boundary for each well in two hours or less. The process will become faster over time as it becomes more automated.

ADWR Demonstration Project Report Response to Cone of Depression Test Comments 26 May 2017

16. Does ADWR agree that a steady state model is incapable of providing the Court, the Department, and the parties with information about how many years it will take for a well’s cone of depression to reach the edge of the subflow zone?

Yes.

17. A linesink element or set of linesink elements may be more appropriate to represent the San Pedro River than the image well method in analytic modeling, like AquiferWin32. The analysis should include a sensitivity analysis between linesinks and image wells to determine if they give the same results.

ADWR did investigate the use of linesinks within AquiferWin32©. ADWR found that the drawdown calculations were affected by the length of the constant head linesink. Increasing the length of the linesink decreased the amount of the calculated drawdown. This added a variable to the analysis that was not present when using image wells.

18. If more sophisticated MODFLOW numerical groundwater models are appropriate for purposes of administering ADWR’s Active Management Area Program, does the Department agree that MODFLOW numerical groundwater models should also be used for testing cones of depression?

No. As shown in the Demonstration Project and in the discussion above, the use of MODFLOW is not required for the Cone of Depression Test.

ADWR Demonstration Project Report Response to Cone of Depression Test Comments 27 May 2017

TABLES

Table 1 - Changes in Calculated Drawdown Resulting from Variations in Models and Methodology

Column 1 Column 2 Column 3 Column 4 Column 5 Column 6 Column 7 Column 8 Column 9

Recharge at Recharge at Center ADWR's Original Recharge at Center of Original Recharge at Mtn Frnt Mountain Front of Subflow Zone Muliple Image Wells Subflow Zone Steady State MODFLOW (AquiferWin32© (Jacob Steady (Jacob Steady Well Map No. Well Name (AquiferWin32© (AquiferWin32© Pumping Rate - Q Drawdown (ft) Method) Drawdown State Method) State Method) Method) Drawdown (ft) Method) Drawdown (gpm) at SFZ* (ft) at SFZ Drawdown (ft) at Drawdown (ft) at at SFZ (ft) at SFZ SFZ SFZ

31 111-24-086-W1 0.007 0.009 0.024 0.004 0.02 0.03 0.5 14 111-23-041-W1 0.023 0.004 0.001 0.002 0.00 0.03 3.1 19 111-23-025-W2 0.016 0.006 0.010 0.002 0.01 0.02 4.0 22 111-23-028-W1 0.030 0.006 0.006 0.002 0.01 0.02 4.0 16 111-20-062-W22N 0.020 0.059 0.013 0.015 0.01 0.18 4.2 17 111-23-066-W1 0.020 0.211 0.536 0.083 0.53 0.65 5.0 24 111-23-029-W1 0.039 0.020 0.007 0.006 0.01 0.07 5.7 1 111-23-ADC-031-W1 0.020 0.099 0.272 0.047 0.29 0.25 6.8 20 111-23-030-W14 0.049 0.084 0.076 0.019 0.08 0.30 7.2 21 111-23-030-W13 0.049 0.062 0.054 0.019 0.05 0.22 7.2 23 111-23-030-W3 0.049 0.007 0.004 0.002 0.00 0.03 7.2 3 111-23-ADC-060-W1 0.033 0.110 0.322 0.048 0.32 0.31 7.3 26 111-20-062-W18 0.046 5.870 1.168 2.070 1.16 12.96 7.5 11 111-24-CBC-063-W1 0.958 0.089 0.192 0.073 0.19 0.09 7.7 12 111-24-CBC-072-W1 0.872 0.120 0.313 0.092 0.32 0.14 8.4 6 111-23-DDA-016-W1 0.115 0.105 0.282 0.054 0.28 0.16 11.0 36 111-24-060-W6N 0.112 0.027 0.079 0.013 0.08 0.14 11.2 37 111-24-060-W2 0.112 0.072 0.204 0.036 0.20 0.38 11.2 40 111-24-060-W8N 0.112 0.115 0.069 0.047 0.07 0.67 11.2 41 111-24-060-W7N 0.112 0.033 0.094 0.016 0.09 0.17 11.2 2 111-23-ADC-059-W1 0.052 0.111 0.322 0.049 0.32 0.32 12.1 18 111-23-025-W1 0.052 0.010 0.017 0.003 0.02 0.03 12.3 10 111-24-CBC-022-W1 2.591 2.300 3.407 2.104 3.80 2.56 13.4 15 111-23-BDCA-009-W1 0.098 0.516 0.090 0.169 0.09 2.44 14.1 25 111-20-062-W17 0.118 0.287 0.106 0.106 0.07 0.45 18.2 8 111-23-DDA-023-W1 0.174 0.109 0.271 0.055 0.27 0.16 19.8 30 111-24-BDC-008-W1 0.499 11.310 3.674 3.109 3.62 19.06 22.7 27 111-23-027-W2 0.522 1.060 2.789 0.442 2.78 1.92 35.4 13 111-24-CBC-078-W1 3.510 0.690 1.732 0.506 1.37 0.66 47.5 29 111-24-CBC-005-W1 1.797 1.550 3.596 1.076 3.56 1.74 70.0 9 111-24-CBB-001-W1 11.270 1.620 3.690 1.333 3.58 1.62 70.6 5 111-23-DDA-006-W1 0.797 1.710 4.196 0.792 4.15 2.68 71.3 28 111-24-CCB-002-W1 1.817 0.220 0.533 0.165 0.53 0.27 129.4 32 111-24-075-(59)-W1 1.748 0.468 1.337 0.231 1.33 2.25 176.4 33 111-24-075-(59)-W3 1.748 0.478 1.333 0.234 1.33 2.28 176.4 34 111-24-075-(59)-W2 1.748 0.639 1.798 0.313 1.79 3.09 176.4 35 111-24-075-(59)-W4N 1.748 0.107 0.308 0.053 0.31 0.53 176.4 38 111-24-DCD-012-W1 1.886 0.654 1.776 0.318 1.76 3.44 190.5 4 111-23-DAD-006-W6 36.752 5.620 13.491 3.950 13.07 6.49 390.7 7 111-23-DDA-022-W1 1.519 8.220 20.166 4.883 18.81 9.27 395.8 39 111-24-DCD-010-W4 3.979 1.990 4.057 0.905 3.99 10.86 399.9

Concurs with MODFLOW Alternative Model Subject to the Adjudication / MODFLOW Not Subject to the Adjudication MODFLOW Subject to the Adjudication / Alternative Model Not Subject to the Adjudication * SFZ - ADWR Proposed subflow zone

ADWR Demonstration Project Report Response to Cone of Depression Test Comments May 2017 Table 2 - Changes in Calculated Drawdown Resulting from Variations in Input Parameters

Column 1 Column 2 Column 3 Column 4 Column 5 Column 6 Column 7 Column 8 Column 9 Column 10 Column 11 Column 12 Column 13

Pumping Well Moved Pumping Well Moved Decrease Increase Transmissivity Reference Head Moved ADWR's Original Reference Head Moved Original Increase Pumping by Decrease Pumping by Closer to SFZ Centerline Further From theSFZ Transmissivity by An by An Order of an Additional 10 Miles Original Muliple Image Wells 10 Miles South MODFLOW 25% (AquiferWin32© 25% (AquiferWin32© by 500 ft Centerline by 500 ft Order of Magnitude Magnitude North** Pumping Rate (AquiferWin32© (AquiferWin32© Drawdown (ft) Method) Drawdown (ft) Method) Drawdown (AquiferWin32© (AquiferWin32© (AquiferWin32© (AquiferWin32© (AquiferWin32© (gpm) Method) Drawdown Method) Drawdown at SFZ* at SFZ (ft) at SFZ Method) Drawdown Method) Drawdown Method) Drawdown Method) Drawdown (ft) Method) Drawdown (ft) at SFZ (ft) at SFZ (ft) at SFZ (ft) at SFZ (ft) at SFZ at SFZ (ft) at SFZ Well Map No. Well Name

19 111-23-025-W2 4.0 0.016 0.006 0.006 0.006 0.058 0.001 0.008 0.004

6 111-23-DDA-016-W1 11.0 0.115 0.105 0.079 0.101 1.054 0.010 0.128 0.082

29 111-24-CBC-005-W1 70.0 1.797 1.550 1.158 1.431 16.323 0.154 1.757 1.329

Concurs with MODFLOW Alternative Model Subject to the Adjudication / MODFLOW Not Subject to the Adjudication MODFLOW Subject to the Adjudication / Alternative Model Not Subject to the Adjudication

* SFZ - ADWR Proposed subflow zone ** Reference head is originally set 30 miles north of the pumping well, on the centerline of the subflow zone. Columns 12 and 13 display the drawdown calculations resulting from moving the reference head 10 miles further north (Column 12), and also 10 miles south (Column 13) of the original location.

ADWR Demonstration Project Report Response to Cone of Depression Test Comments May 2017

FIGURES

Z o n S e u Well Map No. 19: 111-23-025-W2

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Distance to Reference Head: 30 miles north of 0.25 pumping well along the subflow zone centerline 40000 35000 30000 25000 20000 15000 10000 5000 0 Distance from Western Subflow Boundary (ft) Reference Head: 4452 ft

0 1 ! Original Well Location Miles )" Adjusted Well Location Pinal Graham Well Map No. 19: 111-23-025-W2 Well Map No. 19: 111-23-025-W2 Well Map No. 19: 111-23-025-W2 Pumping Increased by 25% Well Moved Closer to the Subflow Zone Centerline by 500 ft Transmissivity Decreased by Order of Magnitude 0 0 0

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0.25 0.25 2 Demonstration Project Area 40000 35000 30000 25000 20000 15000 10000 5000 0 40000 35000 30000 25000 20000 15000 10000 5000 0 40000 35000 30000 25000 20000 15000 10000 5000 0 Santa Cruz Distance from Western Subflow Boundary (ft) Distance from Western Subflow Boundary (ft) Distance from Western Subflow Boundary (ft)

Well Map No. 19: 111-23-025-W2 Well Map No. 19: 111-23-025-W2 Well Map No. 19: 111-23-025-W2 Transmissivity Increased by Order of Magnitude Reference Head Moved 10 Miles South 0 Reference Head Moved 10 Miles North 0 0 Figure 1

0.05 0.05 0.05 Well Map No. 19: 111-23-025-W2 e e e n n n o o Z o Z

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0.15 D D u 0.15 0.15 s e e P e W W

W Response to Cone of Depression Test Comments 0.2 0.2 0.2 May 2017 0.25 0.25 0.25 40000 35000 30000 25000 20000 15000 10000 5000 0 40000 35000 30000 25000 20000 15000 10000 5000 0 40000 35000 30000 25000 20000 15000 10000 5000 0 Distance from Western Subflow Boundary (ft) Distance from Western Subflow Boundary (ft) Distance from Western Subflow Boundary (ft) Well Map No. 29: 111-24-CBC-005-W1 © Original Demonstration Project Report Run AquiferWin32 Input Parameters ¯ 0 1 Distance from Well to: 2 ADWR Proposed Subflow Zone Centerline: 4,862 ft

3 e 0.1 ft drawdown n ADWR Proposed Subflow Zone Boundary o Z 4 contour l

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7 e t u a r ! )" s Original Cone of Depression Test Modeling P a D 8 E Parameters: 9 y r Pumping Rate: 70.0 gal/min a 10 d n Transmissivity: 1,862.6 ft2/day u 11 o e n B i l r 12 Distance to Reference Head: 30 miles north of e

e t n n 13 pumping well along the subflow zone centerline

o e

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Graham Well Map No. 29: 111-24-CBC-005-W1 Well Map No. 29: 111-24-CBC-005-W1 Well Map No. 29: 111-24-CBC-005-W1 Pumping Decreased by 25% Well Moved Further from the Subflow Zone Centerline by 500 ft Transmissivity Decreased by Order of Magnitude 0 0 0 1 1 10 2 2 20 30 3 3 e e e

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APPENDICES

Example Well Appendix 1 - Example of Driller Log Program

Saturated Sy x Sat K x Sat Driller's Log Perforated interval Category Code Description Thickness Sy Thickness K_gpd/ft2 Thickness k_ft/d From (ft) To (ft) 0 58 Loose Boulders 58 130 Hard Granite Rock 100 to 305 ft HARD ROCKS HARK03 GRANITE 30 0 0 0 0 130 146 Decomposed Granite BEDROCK CRYSTALLINE DEGR01 DECOMPOSED GRANITE 16 3 48 2 32 SWL = 100 ft 146 174 Hard Granite Rock HARD ROCKS HARK03 GRANITE 28 0 0 0 0 174 196 Red Clay Conglomerate GRAVEL AND FINES CMGR02 CEMENTED GRAVEL AND CLAY 22 5 110 20 440 196 230 Cemented Sand & Gravel CEMENTED SAND AND GRAVEL CMSG02 CEMENT, GRAVEL, SAND AND ROCK 34 10 340 100 3400 230 234 Hard Granite Rock HARD ROCKS HARK03 GRANITE 4 0 0 0 0 234 250 Gravel (water) GRAVEL WAGR03 GRAVEL 16 25 400 1500 24000 250 255 Granite Rock HARD ROCKS HARK03 GRANITE 5 0 0 0 0 255 266 Sand & Gravel (water) GRAVEL AND SAND SAGR01 GRAVEL AND SAND 11 25 275 1500 16500 266 273 Hard Granite Rock HARD ROCKS HARK03 GRANITE 7 0 0 0 0 273 280 Gravel (water) GRAVEL WAGR03 GRAVEL 7 25 175 1500 10500 280 286 Red Clay Conglomerate GRAVEL AND FINES CMGR02 CEMENTED GRAVEL AND CLAY 6 5 30 20 120 286 290 Very Hard Conglomerate CONGLOMERATE CNGL01 CONGLOMERATE 4 5 20 20 80 290 291 Sticky Clay Conglomerate CONGLOMERATE CNGS02 CONGOLOMERATE, STICKY CLAY, SAND AND GRAVEL 1 10 10 100 100 291 305 Red Clay CLAYS CLAY04 CLAY 14 3 42 2 28

Totals 205 1450 55200 calculated calculated Sy* 7.1 K** 269.3 gpd/ft2 36.0 ft/d * Equals the sum of (Sy x Sat Thickness) divided by the total saturated thickness. ** Equals the sum of (K x Sat Thickness) divided by the total saturated thickness.

ADWR Demonstration Project Report Response to Cone of Depression Test Comments May 2017 1 Appendix 1 - Predetermined Sy and K values CATEGORY Sy K Code Description HARD ROCKS 0 0 HARK01 HARD BOULDERS HARD ROCKS 0 0 HARK02 HARD ROCK HARD ROCKS 0 0 HARK03 GRANITE HARD ROCKS 0 0 HARK04 ROCK (KNOWN AREA OF CRYSTALLINE ROCKS) LIMESTONE 0 0 LIST01 LIMESTONE BEDROCK 3 2 BERK01 FRACTURED BEDROCK Added sometime later CALICHE 3 2 CALI01 CALICHE CALICHE 3 2 CEMT01 CEMENT CALICHE 3 2 CEMT02 CEMENT LEDGE CLAYS 3 2 CLAY01 ADOBE CLAYS 3 2 CLAY02 BRITTLE CLAY CLAYS 3 2 CLAY03 CAVING CLAY CLAYS 3 2 CLAY04 CLAY CLAYS 3 2 CLAY05 CRUMBLY CLAY CLAYS 3 2 CLAY06 DIRT CLAYS 3 2 CLAY07 GOOD CLAY CLAYS 3 2 CLAY08 HARD CLAY CLAYS 3 2 CLAY09 JOINT CLAY CLAYS 3 2 CLAY10 PACKED CLAY CLAYS 3 2 CLAY11 POOR CLAY CLAYS 3 2 CLAY12 SOFT CLAY CLAYS 3 2 CLAY13 STICKY CLAY CLAYS 3 2 CLAY14 TIGHT CLAY BEDROCK CRYSTALLINE 3 2 DEGR01 DECOMPOSED GRANITE LIMESTONE 3 2 FRLS01 FRACTURED LIMESTONE CALICHE 3 2 HAPN01 HARDPAN VOLCANICS 3 2 MALA01 MALAPAI SHALE 3 2 SHAL01 HARDPAN SHALE SHALE 3 2 SHAL02 LOOSE SHALE SHALE 3 2 SHAL03 SHALE LIMESTONE 3 2 SHEL01 SHELL VOLCANICS 3 2 VOLC01 LAVA VOLCANICS 3 2 VOLC02 VOLCANIC ROCK GRAVEL 5 20 CMGR01 CEMENTED GRAVEL (COBBLES) GRAVEL AND FINES 5 20 CMGR02 CEMENTED GRAVEL AND CLAY GRAVEL 5 20 CMGR03 CEMENT AND ROCKS SAND 5 20 CMSA01 CEMENTED SAND SAND AND CLAY 5 20 CMSA02 CEMENTED SAND AND CLAY SAND AND CLAY 5 20 CMSA03 CEMENTED SANDY CLAY CONGLOMERATE 5 20 CNGL01 CONGLOMERATE GRAVELLY CLAYS 5 20 CRCL01 CLAY AND BOULDERS (COBBLES) GRAVEL 5 20 DRGR01 DRY GRAVEL (BELOW WATER TABLE) GRAVELLY CLAYS 5 20 GRCL02 CLAY AND GRAVEL (ROCK) GRAVELLY CLAYS 5 20 GRCL03 COBBLES IN CLAY GRAVELLY CLAYS 5 20 GRCL04 GRAVEL AND CLAY GRAVELLY CLAYS 5 20 GRCL05 GRAVELLY CLAY GRAVELLY CLAYS 5 20 GRCL06 ROCKS IN CLAY SAND 5 20 HASA01 CLAY SAND SAND 5 20 HASA02 DRY HARD PACKED SAND SAND 5 20 HASA03 DRY SAND AND DIRT SAND 5 20 HASA04 DRY SAND (BELOW WATER TABLE) SAND 5 20 HASA05 FINE MUDDY SAND SAND 5 20 HASA06 HARD PACKED SAND WITH STREAKS OF CLAY SAND 5 20 HASA07 SET SAND WITH STREAKS OF CLAY SAND AND CLAY 5 20 HSCL01 CLAY WITH CEMENTED SAND SAND AND CLAY 5 20 HSCL02 CLAY AND FINE SAND SAND AND CLAY 5 20 HSCL03 CLAY AND COARSE SAND SAND AND CLAY 5 20 HSCL04 FINE SAND WITH STREAKS OF CLAY SAND AND CLAY 5 20 HSCL05 HARD SAND AND CLAY SAND AND CLAY 5 20 HSCL06 MUDDY SAND AND CLAY SAND AND CLAY 5 20 HSCL07 PACKED SAND AND CLAY SAND AND CLAY 5 20 HSCL08 SAND AND CLAY MIX SAND AND CLAY 5 20 HSCL09 STICKY SAND AND CLAY SANDY CLAYS 5 20 HSYC01 CLAY AND SANDY CLAY SANDY CLAYS 5 20 HSYC02 CLAY AND SILT SANDY CLAYS 5 20 HSYC03 CLAY WITH COMPACTED LOAM AND SAND SANDY CLAYS 5 20 HSYC04 CLAY WITH OCCASIONAL ROCK SANDY CLAYS 5 20 HSYC05 CLAY, PACK SAND AND GRAVEL

ADWR Demonstration Project Report Response to Cone of Depression Test Comments May 2017 2 CATEGORY Sy K Code Description SANDY CLAYS 5 20 HSYC06 CLAY WITH STREAKS OF SANDY CLAY SANDY CLAYS 5 20 HSYC07 CLAY WITH SAND POCKET SANDY CLAYS 5 20 HSYC08 CLAY WITH THIN STREAKS OF SAND SANDY CLAYS 5 20 HSYC09 CLAY WITH WATER SANDY CLAYS 5 20 HSYC11 HARD SANDY CLAY (TIGHT) SANDY CLAYS 5 20 HSYC12 QUICKSANDY CLAY SANDY CLAYS 5 20 HSYC13 SANDY CLAY SANDY CLAYS 5 20 HSYC14 SANDY CLAY LOAM SANDY CLAYS 5 20 HSYC15 SOFT SANDY CLAY SANDY CLAYS 5 20 HSYC16 SOLID CLAY WITH STRATA OF CEMENTED SAND HARDPAN 5 20 SAHP01 DECOMPOSED HARDPAN HARDPAN 5 20 SAHP02 HARDPAN AND SANDSTONE HARDPAN 5 20 SAHP03 HARDPAN AND SANDY CLAY HARDPAN 5 20 SAHP04 HARDPAN AND SANDY SHALE HARDPAN 5 20 SAHP05 HARDPAN AND SANDY STRATAS HARDPAN 5 20 SAHP06 SANDY HARDPAN HARDPAN 5 20 SAHP07 SEMI-HARDPAN HARDPAN 5 20 SAHP08 TOP HARDPAN SOIL SANDSTONE 5 20 SAST01 SANDSTONE SANDSTONE 5 20 SAST02 SANDSTONE AND FLOAT ROCK SANDSTONE 5 20 SAST03 SANDSTONE AND LAVA SANDSTONE 5 20 SAST04 SAND ROCK SANDSTONE 5 20 SAST05 SAND SHELL SILTS 5 20 SILT01 DRY SANDY SILT SILTS 5 20 SILT02 SILT SILTS 5 20 SILT03 SILT AND CLAY SILTS 5 20 SILT04 SILT AND GRAVEL SILTS 5 20 SILT05 SILTY CLAY SILTS 5 20 SILT06 SILTY CLAY LOAM SILTS 5 20 SILT07 SILTY LOAM SOILS 5 20 SOIL01 FINE SANDY LOAM SOILS 5 20 SOIL02 LOAM SOILS 5 20 SOIL03 LOAM AND CLAY SOILS 5 20 SOIL04 SOFT LOAM SOILS 5 20 SOIL05 SOIL SOILS 5 20 SOIL06 SOIL AND BOULDERS SOILS 5 20 SOIL07 SOIL AND CLAY SOILS 5 20 SOIL08 SOIL AND MUD SOILS 5 20 SOIL09 SOIL AND SANDY SHALE SOILS 5 20 SOIL10 TOPSOIL SOILS 5 20 SOIL11 TOPSOIL AND SANDY SILT SOILS 5 20 SOIL12 TOPSOIL-SILT VOLCANICS 5 20 VASH01 HARD LAVA FORMATION VOLCANICS 5 20 VASH02 VOLCANIC ASH CLAY GRAVEL 10 100 CLGR01 CLAY AND GRAVEL (WATER BEARING) CLAY GRAVEL 10 100 CLGR02 CLAY AND ROCK WITH SOME LOOSE ROCK CLAY GRAVEL 10 100 CLGR03 SANDY CLAY AND GRAVEL CEMENTED SAND AND GRAVEL 10 100 CMSG01 BOULDERS WITH CEMENTED SAND CEMENTED SAND AND GRAVEL 10 100 CMSG02 CEMENT, GRAVEL, SAND AND ROCK CEMENTED SAND AND GRAVEL 10 100 CMSG03 HARD SAND AND GRAVEL CEMENTED SAND AND GRAVEL 10 100 CMSG04 PACKED SAND AND GRAVEL CEMENTED SAND AND GRAVEL 10 100 CMSG05 SAND AND GRAVEL WITH CEMENTED STREAKS CONGLOMERATE 10 100 CNGS01 CONGOLOMERATE, GRAVEL AND BOULDERS CONGLOMERATE 10 100 CNGS02 CONGOLOMERATE, STICKY CLAY, SAND AND GRAVEL GRAVEL 10 100 HAGR01 DIRTY GRAVEL GRAVEL 10 100 HAGR02 FINE GRAVEL, HARD GRAVEL 10 100 HAGR03 HARD GRAVEL GRAVEL 10 100 HAGR04 GRAVEL AND HARDPAN STRATA GRAVEL 10 100 HAGR05 GRAVEL WITH STREAKS OF CLAY GRAVEL 10 100 HAGR06 GRAVEL AND CEMENTED SAND GRAVEL 10 100 HAGR07 PACKED GRAVEL GRAVEL 10 100 HAGR08 SET GRAVEL GRAVEL 10 100 HAGR09 TIGHT GRAVEL SAND 10 100 QKSA01 QUICKSAND GRAVEL AND SAND 10 100 QKSA02 QUICKSAND AND COBBLES SAND AND CLAY 10 100 SACL01 BRITTLE CLAY AND SAND SAND AND CLAY 10 100 SACL02 CLAY AND SAND SAND AND CLAY 10 100 SACL03 CLAY, SAND AND WATER SAND AND CLAY 10 100 SACL04 HARD SAND AND STREAKS OF SANDY CLAY SAND AND CLAY 10 100 SACL05 ROCK, SAND AND CLAY

ADWR Demonstration Project Report Response to Cone of Depression Test Comments May 2017 3 CATEGORY Sy K Code Description SAND AND CLAY 10 100 SACL06 SAND AND CLAY SAND AND CLAY 10 100 SACL07 SAND AND SANDY CLAY SAND AND CLAY 10 100 SACL08 SOIL, SAND AND CLAY SAND 10 100 SAHR01 SAND AND LAVA SAND AND CLAY 10 100 SAHR02 SAND AND TOUGH SHALE SAND 10 100 SAND01 CLOGGY SAND SAND 10 100 SAND02 COARSE, AND SANDY SAND 10 100 SAND03 COARSE PACK SAND SAND 10 100 SAND04 DEAD SAND SAND 10 100 SAND05 DIRTY SAND SAND 10 100 SAND06 FINE PACK SAND SAND 10 100 SAND08 HARD SAND SAND 10 100 SAND09 HARD SAND ROCK AND SOME WATER SAND SAND 10 100 SAND10 HARD SAND WITH SOFT STREAKS SAND 10 100 SAND11 LOAMY FINE SAND SAND 10 100 SAND12 MUDDY SAND SAND 10 100 SAND13 MORE OR LESS SAND SAND 10 100 SAND14 POOR WATER SAND SAND 10 100 SAND15 SAND AND PACK SAND SAND 10 100 SAND16 SAND CRUST SAND 10 100 SAND17 SAND, MUD AND WATER SAND 10 100 SAND18 SAND WITH SOME WATER SAND 10 100 SAND19 SAND STREAKS, BALANCE CLAY SAND 10 100 SAND20 SAND WITH STREAKS OF CLAY SAND 10 100 SAND21 SAND WITH CEMENTED STREAKS SAND 10 100 SAND22 SET SAND SAND 10 100 SAND23 STICKY SAND SAND 10 100 SAND24 STREAKS FINE AND COARSE SAND SAND 10 100 SAND25 SURFACE AND FINE SAND SAND 10 100 SAND26 TIGHT SAND SAND AND SOIL 10 100 SAS01 COMPACTED SAND AND SILT SAND AND SOIL 10 100 SAS02 MUD AND SAND SAND AND SOIL 10 100 SAS03 MUD, SAND AND WATER SAND AND SOIL 10 100 SAS04 SAND AND DIRT SAND AND SOIL 10 100 SAS05 SAND AND HARDPAN SAND AND SOIL 10 100 SAS06 SAND AND HARD SAND SAND AND SOIL 10 100 SAS07 SAND AND MUD WITH CHUNKS OF CLAY SAND AND SOIL 10 100 SAS08 SAND AND SOIL SAND AND SOIL 10 100 SAS09 SANDY LOAM SAND AND SOIL 10 100 SAS10 SANDY LOAM, SAND AND CLAY SAND AND SOIL 10 100 SAS11 SANDY MULCH SAND AND SOIL 10 100 SAS12 SANDY SEDIMENT SAND AND SOIL 10 100 SAS13 SANDY SILT SAND AND SOIL 10 100 SAS14 SANDY SOIL SAND AND SOIL 10 100 SAS15 SILT AND FINE SAND SAND AND SOIL 10 100 SAS16 SILT AND SAND SAND AND SOIL 10 100 SAS17 TOPSOIL AND LIGHT SAND SAND, CLAY AND GRAVEL 10 100 SCGR01 CLAY, SAND AND GRAVEL SAND, CLAY AND GRAVEL 10 100 SCGR02 CLAY, SILT, SAND AND GRAVEL SANDY, CLAY AND GRAVEL 10 100 SCGR04 SAND, CLAY, WITH STREAKS OF GRAVEL SANDY, CLAY AND GRAVEL 10 100 SCGR03 MORE OR LESS CLAY, HARD SAND AND BOULDERS SAND 10 100 SFSS01 SOFT SANDSTONE SANDY CLAY 10 100 VSYC01 CLAY AND SAND SANDY CLAY 10 100 VSYC02 CLAY WITH SAND STREAKS SANDY CLAY 10 100 VSYC03 LOOSE SANDY CLAY SANDY CLAY 10 100 VSYC04 SAND, CLAY AND WATER SANDY CLAY 10 100 VSYC05 SANDY CLAY WATER BEARING SANDY CLAY 10 100 VSYC06 SANDY CLAY WITH STREAKS OF SAND SANDY CLAY 10 100 VSYC07 SANDY FORMATION SANDY CLAY 10 100 VSYC08 VERY SANDY CLAY SAND 15 400 FISA01 FINE SAND GRAVEL, SAND AND FINES 15 400 SISG03 SILTY SAND AND GRAVEL (COBBLES) GRAVEL, SAND AND FINES 15 400 SISG01 SAND AND SILT, (MAINLY GRAVEL) SAND AND SILT 15 400 SISG02 SILTY SAND GRAVEL 25 1500 BOUL01 BOULDERS GRAVEL 25 1500 BOUL02 COBBLESTONES GRAVEL 25 1500 BOUL03 COBBLES GRAVEL 25 1500 BOUL04 ROCKS GRAVEL AND SAND 25 1500 SABO01 SAND AND BOULDERS GRAVEL AND SAND 25 1500 SABO02 SAND AND COBBLES

ADWR Demonstration Project Report Response to Cone of Depression Test Comments May 2017 4 CATEGORY Sy K Code Description GRAVEL AND SAND 25 1500 SAGR01 GRAVEL AND SAND GRAVEL AND SAND 25 1500 SAGR02 GRAVEL AND SAND ROCK GRAVEL 25 1500 SAGR03 ROCK AND GRAVEL GRAVEL 25 1500 WAGR01 COARSE GRAVEL GRAVEL 25 1500 WAGR02 DRY GRAVEL (ABOVE WATER TABLE) GRAVEL 25 1500 WAGR03 GRAVEL GRAVEL 25 1500 WAGR04 LOOSE GRAVEL GRAVEL 25 1500 WAGR05 SANDY GRAVEL GRAVEL 25 1500 WAGR06 WATER GRAVEL SAND 25 1500 WASA01 COARSE SAND SAND 25 1500 WASA02 FREE SAND SAND 25 1500 WASA03 LOOSE SAND SAND 25 1500 WASA04 RUNNING SAND SAND 25 1500 WASA05 SAND SAND 25 1500 WASA06 SAND WITH WATER

ADWR Demonstration Project Report Response to Cone of Depression Test Comments May 2017 5

APPENDIX 2 APPENDIX 2

Cone of Depression Testing Methodology

The Cone of Depression testing methodology described below revises the methodology described in Chapter 3 of ADWRs 2002 Subflow Technical Report (ADWR, 2002). ADWR plans to use the revised methodology to conduct its initial determinations as to whether the PWR served by a well is subject to the adjudication. ADWR plans to make the results of its initial determinations informally available to well owners, and evaluate any additional information provided by well owners prior to final publication of results. The revised methodology consists of the following:

1. Determine well location.

o The maps contained in Volume 9 of the 1991 San Pedro I HSR (ADWR, 1991) have been scanned, and the mapped well locations can be digitized into ADWR’s GIS. Well locations within GIS can be compared to aerial and satellite imagery in GIS. If the true location of the well can be seen on the imagery, the GIS well location can be matched to the actual location.

o ADWR will locate unmapped wells using the San Pedro I HSR, well records, county assessor parcel information, and ArcGIS aerial/satellite imagery.

2. Determine distance from the subject well to ADWR’s proposed subflow zone boundary and the proposed subflow zone centerline.

o ADWR’s GIS will be used to find the shortest distance between the subject well and the proposed subflow zone boundary.

o The location of the subflow zone centerline is calculated in ArcGIS as the center points of the shortest lines from one subflow zone boundary to the opposite subflow zone boundary. ArcGIS can then calculate the distance from the subject well to the subflow zone centerline.

ADWR Demonstration Project Report Response to Cone of Depression Test Comments 1 May 2017

3. Determine distance from the subject well to the impermeable barrier (“hard rock”).

o The surface expression of consolidated non-alluvial materials (“hard rock”) have been incorporated into the GIS. The surface expressions were generalized, based on hardrock contours from Richard et al., 2000. ADWR’s GIS can be used to find the shortest distance between the subject well and the generalized surface expression of the hard rock.

4. Determine steady-state pumping rate (Q).

o ADWR will determine the steady state pumping rate for each well in gallons per minute (gpm) by estimating the annual use in acre-feet and multiplying by a conversion factor of 0.62.

o Annual “maximum observed” volumes of use for irrigation PWRs will be collected from the 1991 San Pedro I HSR. Volumes of use will be evenly distributed among the wells serving each irrigation PWR.

o ADWR will evenly distribute the “apparent annual volume used” for each municipal (MU) PWR in the San Pedro I HSR to each well serving the PWR to determine that well’s annual volume withdrawn.

o Annual uses for other PWRs will be based on the volumes reported in the San Pedro I HSR.

5. Define local aquifer properties.

o The Drillers Log program (Kisser, K.G. and Haimson, 1981) will be used to initially estimate the hydraulic conductivity of each well tested using the AquiferWin32© program.

o For each well, a weighted average hydraulic conductivity based on the saturated thickness of each lithologic interval will determined. Where possible, the driller’s log for the subject well will be evaluated. If the subject well does not

ADWR Demonstration Project Report Response to Cone of Depression Test Comments 2 May 2017

have a log available, then wells in the vicinity of the subject well will be evaluated.

o The aquifer saturated thickness will be set to the well’s largest measured saturated thickness. ADWR will use the shallowest known water level measurement and the total depth of the well to calculate the saturated thickness of the well. If there are no available water level measurements or well depths, then ADWR will contact the well owner and attempt to collect such measurements.

6. Construct a conceptual model of the aquifer system

o ADWR believes that the appropriate conceptual model for the San Pedro River watershed is a perennial stream with impermeable barriers present on both sides.

7. Select a mathematical model

o Based on the results of the Demonstration Project (ADWR, 2017) and the additional investigations described in this report, ADWR believes that the analytical model AquiferWin32© (ESI, 2011) is the appropriate mathematical model for conducting cone of depression testing. Image wells will be used to emulate the perennial stream and impermeable boundaries of the conceptual model (Ferris et al., 1962).

8. Input data and run a simulation using the selected mathematical model.

o In AquiferWin32©, ADWR will set the 0,0 point of the analytical model at the centerline of the subflow zone orthogonal to the location of the pumping well. The following parameters will be entered into the AquiferWin32© program for the analysis:

ADWR Demonstration Project Report Response to Cone of Depression Test Comments 3 May 2017

. Model type: steady state . Time units: minutes, length units: feet, pumping rate units: gal/min, and transmissivity units: sq ft/d . Contour resolution (grid) set to 1000 X Nodes by 1000 Y Nodes . Reference head (ft) . Reference head location (ADWR will use 30 miles north of the 0,0 point) . Aquifer top and aquifer bottom (ft) elevation for calculation of saturated thickness . Hydraulic conductivity (ft/day) for transmissivity calculation . Image well locations based on the shortest distance to the centerline of the subflow zone (B/2 as shown in Figure 3-4 of the Demonstration Project Report) . Image well locations based on the shortest distance to the impermeable barrier (A/2 as shown in Figure 3-4 of the Demonstration Project Report) . Pumping rate per real discharging well, discharging image wells, and recharging image wells . A line calculation starting from the subflow zone boundary to the center of the subject well location, as well as one starting at the subflow zone centerline to the center of the subject well. The line calculation displays drawdown per unit length.

9. Analyze model output

o A line calculation which starts at the subflow zone boundary and ends at the center of the subject well location displays the drawdown data based on a specified interval (ADWR will use 20 intervals). After the AquiferWin32© analytical model is run, the drawdown data can be examined from within the line calculation object.

ADWR Demonstration Project Report Response to Cone of Depression Test Comments 4 May 2017

10. Determine whether a well is subject to the adjudication

o If the drawdown at the subflow zone boundary (0 ft distance value from the Line Calculation Data tab) is 0.1 ft. or greater, then the PWR served by the well is subject to the adjudication. If the drawdown is less than 0.1 ft. then the PWR served by the well is not subject to the adjudication.

ADWR Demonstration Project Report Response to Cone of Depression Test Comments 5 May 2017