Pahrump Groundwater Plan Evaluation in Regards to Identifying Projects for Preliminary Engineering Reports

Nye County Water District Pahrump Groundwater Plan Evaluation in Regards to Identifying Projects for Preliminary Engineering Reports

Prepared by: Shaw Engineering Interflow Hydrology Paul Winkelman, P.E. Dwight Smith, P.E., P.G. Scott Benedict, P.E.

June 2nd 2017 Nye County Water District Pahrump GW Plan Evaluation in June 2017 Regards to Identifying Projects for PER

Abbreviations used in Report

AFA Acre-Feet Annually AMSL Above Mean Sea Level AS Aquifer Storage ASR Aquifer Storage and Recovery AR Artificial Recharge BOCC Nye County Board of Commissioners DUI Desert Utilities Inc USEPA US Environmental Protection Agency FMP Flood Master Plan GBWC Great Basin Water Company GPCD, gpcd Gallons Per Capita per Day GPD, gpd Gallons Per Day GPM, gpm Gallons Per Minute HGL Hydraulic Grade Line IRP Integrated Resource Plan ISDS Individual Sewer Disposal System (septic) LVVWD Las Vegas Valley Water District MGD, mgd Million Gallons per Day Mg/l, mg/l Milligrams Per Liter NCPW Nye County Public Works NCWD Nye County Water District NDEP Nevada Department of Environmental Protection NDWR Nevada Division of Water Resources PUCI Pahrump Utility Co. Inc. PER Preliminary Engineering Report PUC Public Utility Company PUCN Public Utilities Commission of Nevada RI Rapid Infiltration RIBS Raised Infiltration Basins WWTP Wastewater Treatment Plant

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Acknowledgments

The assistance of Susan Rybarski and Greg Pohll with the Desert Research Institute on the utilization of the ground water flow model was greatly appreciated. In addition, Jimmy Hou’s and Patrick Johnson’s contributions in the analysis of geographical data and preparation of exhibits was extremely valuable.

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Pahrump Groundwater Plan Evaluation in Regards to Identifying Projects for Preliminary Engineering Reports

Table of Contents

Page Abbreviations i

Acknowledgements ii

Table of Content iii

Section

1.0 Executive Summary 1-1

2.0 Introduction 2-1

3.0 Review of Basin 162 Hydrology 3-1

4.0 Existing Basin Water Balance 4-1

5.0 DRI Model Utilization and Limitations 5-1

6.0 Re-Distribution of Production Wells 6-1

7.0 Flood Detention Rapid Infiltration Basin Conversion 7-1

8.0 Wastewater Treatment and Individual Sewage Disposal Systems Potential Return Flows 8-1

9.0 Aquifer Storage and Recovery and Artificial Recharge in Regards to Basin 162 9-1

10.0 Potential Future Basin Water Balance 10-1

11.0 Backbone Infrastructure and Create Incentives to Voluntarily Connect to Public Water Systems 11-1

12.0 Wastewater Treatment and Individual Sewage Disposal Systems Water Quality Considerations 12-1

13.0 Conclusion and Recommendations 13-1

14.0 References 14-1

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List of Tables Page

Table 2-1: Committed Water Rights – Basin 162 2-1

Table 4-1: Pahrump Valley Water Balance Summary 4-3

Table 5-1: Water Balance Components in the DRI Model (2017 Updated Version) 5-1

Table 6-1: Re-Distribution of 2,000 AFA of Pumping to Fan – Facility Cost Opinion 6-7

Table 6-2: Highway 160 Corridor Well Construction – Facility Cost Opinion 6-9

Table 6-3: Stateline 8,000 AFA of Deep Wellfield Pumping – Facility Cost Opinion 6-12

Table 7-1: Pahrump Flood Plan – Proposed Detention Basins with Incremental Construction and O&M Cost Increase to Convert a Portion Located on the Fan to Infiltration Basins 7-4

Table 7-2: Summary of Flood Control Basins Simulated for AR Infiltration 7-6

Table 8-1: WWTP Influent Flow and Flow per Customer, 2016 8-1

Table 8-2: WWTP Effluent Disposal, 2016 8-1

Table 9-1: Cost Opinion to Utilize a RIB to Recharge Manse Spring 9-4

Table 10-1: Estimate of Current Consumptive Use of Groundwater 10-1

Table 10-2: Estimate of Possible Consumptive Use of Groundwater by 2060 10-2

Table 10-3: Water Rights Commitments Summary for Current Conditions 10-4

Table 10-4: Water Rights Commitments Estimate for Future Conditions (2065) 10-5

Table 11-1: Existing Water System Approximate Service Elevation Ranges 11-3

Table 11-2: 24-inch Valley-Utility Inter-Connect Transmission Main Cost Opinion 11-2

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List of Tables-cont. Page

Table 12-1: WWTP Effluent Total Nitrogen Discharged 12-2

Table 12-2: Estimated ISDS Effluent Total Nitrogen Discharged 12-3

Table12-3: Estimated Cost to Add Filtration and Reverse Osmosis and Water Lost 12-7

Table 13-1: Cost per AFA for Artificial Recharge of Stormwater and Manse Spring 13-1

List of Figures

Figure 3-1: Hydrographic Basin Map 3-2

Figure 4-1: Predevelopment Water Balance Schematic 4-3

Figure 4-2: Current Water Balance Schematic 4-4

Figure 5-1: Simulated Drawdown for Current Conditions and in a 50-year Future Scenario with Population Growth Rate of 1.5% 5-2

Figure 6-1: Northern Pahrump Alluvial Fan Pumping Redistribution Scenario (2,000 AFA) in 50 years at 1.5% Growth 6-2

Figure 6-2: Pumping Redistribution Scenarios into Clark County at 8,000 AFA, at 50 years with 1.5% Growth 6-3

Figure 6-3: Pumping Redistribution Scenario to a Deep Stateline Wellfield 6-4

Figure 6-4: Proposed Facilities to Re-Distribute 2,000 AFA of Pumping to the Fan 6-6

Figure 6-5: Proposed Facilities to Develop 8,000 AFA of Pumping Along Highway 160 Southeast from Pahrump 6-8

Figure 6-6: Proposed Facilities to Develop 8,000 AFA of Pumping for Deep Wellfield Pumping Stateline 6-10

Figure 7-1: Flood Plan – Proposed Detention Basins with Potential Infiltration Basin Modifications to Promote Recharge 7-2

Figure 7-2: Simulated Drawdown in 50 Years at 1.5% Growth with AR Of Stormwater Runoff and Manse Spring Recharge 7-7

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List of Figures-cont. Page

Figure 7-3: Simulated Drawdown in 50 Years at 1.5% Growth with Combined Implementation of Flood Detention Basin AR, Manse Spring and 2,000 AFA Pahrump Fan Pumping Redistribution 7-8

Figure 8-1: Wastewater Treatment Plant Locations 8-1

Figure 9-1: Water System Boundaries and Corresponding Well Productions by Location 9-2

Figure 9-2: Potential Facility Improvements to Utilize Manse Spring for RIB Recharge 9-5

Figure 10-1: Simulated Drawdown with Combined Stormwater and Manse Spring Recharge, Pahrump Fan Pumping Redistribution, and Southern Highway 160 Wellfield Pumping Redistribution 10-7

Figure 10-2: Simulated Drawdown for No Action with 1.5% Growth, and with AR and Pumping Redistribution to Highway 160 Wellfield 10-8

Figure 10-3: Difference in Predicted Drawdown between the 50-year No Action Scenario and Cumulative Actions of AR and Pumping Redistributions, for the 1.5% Growth Scenario 10-9

Figure 11-1: Existing Domestic Wells, Municipal Water System Boundaries With Proposed 24-inch Transmission Main Inter-Connect 11-2

Figure 12-1: Septic System (ISDS) Schematic 12-1

Appendices

Appendix A – GWMP

Appendix B – Soils Maps for Pahrump Valley

Appendix C – Long Term Water Level Trends in Pahrump Valley, Figure 5-1 Taken from “Nye County Water Resource Plan”, April 2017

Appendix D – Public Comments and Responses to Draft Report Dated May 8th 2017

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1.0 Executive Summary

The Nye County Water District (NCWD) contracted with Shaw Engineering to identify potentially viable groundwater resource projects to advance to the preliminary engineering report (PER) level. The primary goal of this investigation was to identify physical infrastructure projects that support the GWMP that can be prioritized from the standpoint of cost versus benefit. The projects evaluated should either increase the sustainable yield, or enhance the capturability of the perennial yield. Secondary objectives included review of potential groundwater quality concerns with individual sewage disposal systems (ISDS) and pharmaceuticals discharged into the environment from WWTP and ISDS.

The Pahrump groundwater Basin 162 is over-appropriated by approximately 43,400 AFA. The sustainable pumping rate based on the present well configuration is on the order of 10,000 AFA to 12,000 AFA, while depletion in storage in the basin fill aquifer is currently estimated at 5,000 AFA. Uncaptured deep carbonate outflow is estimated to be 6,000 AFA to 8,000 AFA.

The results of meetings with NCWD, Pahrump area utilities, NDWR, review of previous studies, and the analysis contained in this report resulted in the following recommended actions (1-deemed essential, 2-required, but not a potential public health concern, 3- potentially needed to support the GWMP objectives):

Rank Description 1 A nitrate sampling program is recommended to determine if elevated levels are occurring. Elevated nitrate levels in groundwater can pose a public health threat therefore it is deemed essential to pursue nitrate sampling. 2 The purchase of the Manse Springs water rights by Nye County is in the best interest of the groundwater users in Basin 162 and it is recommended to initiate negotiations for their acquisition. o If the Manse Spring and water rights can be purchased, then at that time it is recommended to proceed with the planning, design and construction of a rapid infiltration basin (RIB) project to artificially recharge to the Valley basin fill. The estimated cost for physical infrastructure to capture the Spring, route and construct the proposed RIB is $1.9 million. 2 Refine the Desert Research Institute (DRI) ground water model to the level needed to better predict cause and effect reactions of water resource as well as potential water quality mitigation strategies. 2 As recommended by Klenke (2017) and concurred in this report, the physical location of domestic wells should be mapped to the parcel it is located on. Coupled with this effort, the mapping of individual sewer disposal systems (ISDS) is also recommended. 2 It is recommended to explore the extents and ability to capture the deep carbonate outflow. This exploration effort is estimated to cost on the order of $5 million and should be approached in phases.

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Rank Description 3 A southeast wellfield (along Highway 160) can be further refined, potentially in- conjunction with a Stateline deep wellfield if supported by future studies. To geographically disperse drawdown across Basin 162 and/or improve the capturability of the perennial yield, wellfields to the south of Pahrump appear to be needed. Re-distributing wells to the fan, east of their current locations did not have an appreciable impact at reducing drawdown in the Valley over the long- term, but should be re-evaluated when the model up updated. a. The estimated cost for physical infrastructure for the southeast well field (Highway 160) option is $46 million (8,000 AFA pumping). b. The estimated cost for physical infrastructure for a deep Stateline well field option is $69 million (8,000 AFA, with an estimated 450 AFA of outflow capture). c. The estimated cost for physical infrastructure for a backbone transmission main to route 8,000 AFA (5,000 gpm) across Pahrump Valley is $26.3 million. 3 Stormwater infiltration basins are recommended to be considered at all locations where detention/retention basins are proposed; and where soil permeabilities and depth to groundwater supports their application. Adding provisions for infiltration is estimated to add 30% to the stormwater basin construction cost, but this is heavily dependent on size of basin and site specific constraints.

Items with the same number designation could be prioritized further based on feasibility, benefits, community support and/or as opportunities present themselves to combine with other projects to reduce cost. The recommended actions need to be refined beyond the scope of this report, with project specific milestones and detailed budgets that include total project cost (land, easements, permits, water rights and environmental cost are not included in the estimates presented herein). In some cases (such as deep carbonate aquifer exploration), the feasibility of the development of production wells needs to be vetted against permitting, water rights, lands and environmental considerations prior to commencing exploration efforts.

It is proposed the NCWD incorporate the recommendations provided into an Action Plan. In addition to prioritizing projects, the Action Plan would identify critical project milestones, develop detailed total project cost estimates, funding mechanism(s) and project schedules. With some of the projects anticipated to take decades to plan, permit, design and construct the Action Alan would be considered a living document that would require regular updates.

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2.0 Introduction

The Nye County Board of Commissioners (BOCC) in concert with the Nevada Division of Water Resources (NDWR) formed a Committee in January 2014 to develop recommendations for a Groundwater Management Plan, in regards to Pahrump Basin 162. The GWMP identified priority items to be evaluated to support the Committee’s mission statement, “To create an equitable groundwater management plan for the Pahrump Basin and the Pahrump Community that balances water supply and demand today and for the future”.

Basin 162 is one of the most over-appropriated basins in Nevada with the State Engi- neer’s Office setting the perennial yield at 20,000 acre-feet/annually (AFA). The perennial yield includes an outflow component that could be attributed to a deep carbonate aquifer that is currently not being pumped. The current annual pumping of Basin 162 is on the order of 15,742 AFA, while the total estimated water rights allocated is approximately 63,439 AFA. With a perianal yield of 20,000 AFA the resulting overallocation is on the order of 43,400 AFA, but due to over dedications by utilities the actual achievable pumping would be less. In addition, the overallocation of 43,400 does not consider anticipated retirement of over dedicated water rights and returns of non-consumptive use, which are summarized in Section 10.

Table 2-1: Committed Water Rights – Basin 162

Description AFA

Existing Permitted Water Rights 51,496 Existing+Future Domestic Wells 9,770 Manse Spring 2,173 Total Committed Water Rights = 63,439

The aquifer is loosely classified into two sub-basins, the Valley floor (west) and the alluvial fan (east). The water levels in the valley are declining, while the levels in the fan are rising. The bulk of the domestic and production wells are located on the valley floor, while the majority of the remaining wells are within the transition zone between the valley and floor. There are no wells currently in-service that pump from a deep carbonate aquifer in Basin 162.

The Nye County Water District (NCWD) contracted with Shaw Engineering to identify potentially viable projects to take to the preliminary engineering report (PER) level to assist in assessment of cost versus benefit of physical infrastructure. From the review of previous studies, discussions with NCWD staff, meetings with the three major utility companies (Pahrump Utilities, Great Basin Utility Company-formerly Utilities Incorpo- rated of Central Nevada, and Desert Utilities) as well as meetings with both Nye County Public Works (NCPW), and NDWR staff this report focused on the following items (for reference the GWMP is included in Appendix A):

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• Summarize the potential offset to the over allocation water rights figure as described in Chapter 2, paragraph E of the GWMP. The results of this exercise are provided in Section 10, Table 10-4. • Evaluate the redistribution of production wells from areas of declining water levels (valley-transition zone) to areas of rising (alluvial fan) as outlined in Chapter 4, paragraph B of the GWMP. o Three wellfield re-distribution scenarios were evaluated in Section 6 of this report, which included areas east of north-central Pahrump, southeast of Pahrump in Clark County along Highway 160 as well as a Stateline deep wellfield option. • Use of groundwater flow model as a planning tool as described in Chapter 4, paragraph E of the GWMP. Shaw contracted with Interflow Hydrology (Interflow) who utilized a model recently completed by the Desert Research Institute (DRI) to assist in this effort as well as other areas of this report related to groundwater and hydrology. In its present state, the model was beneficial in assessing the cost versus benefit of water resource scenarios, but further refinement is recommended to enhance its capability to aid in future studies. • Estimate incremental benefit (increase in groundwater recharge) of converting flood detention basins to rapid infiltration basins (RIBs), and corresponding added construction and maintenance costs. This effort references portions of the “Pahrump Regional Flood Control District Service Plan”, prepared for Nye Coun- ty Public Works as described in Chapter 5, paragraph F of the GWMP. Section 7 of this report contains the discussion and results of this exercise. • Determine if there are viable options for aquifer storage and recovery (AS/ASR) to benefit the basin as described in Chapter 5, paragraph G of the GWMP. The limited sources of water in the Pahrump Valley and location of existing municipal wells limited this discussion to the potential recharge of a spring into a RIB, see Section 9. • Allow utilities to put in backbone infrastructure to support the goals of the GWMP. This is described in Chapter 5 paragraph H of the GWMP, and a conceptual backbone transmission main to inter-connect utilities was evaluated. Pro- jects of this nature are currently being proposed in the “Great Basin Water Co. Pahrump Division - Water and Sewer System 2017 Integrated Resource Plan”, currently filed with the Public Utility Commission of Nevada (PUCN). • Create incentives to voluntarily connect to public water systems is described in Chapter 5, paragraph I of the GWMP. In this report, this topic is limited to refer- encing proposed tariff changes being submitted to the PUCN by GBWC in their 2017 Integrated Resource Plan (full title above). • From discussions with NCWD staff, the amount of the secondary recharge from residential septic’s is estimated. A discussion of potential water quality issues related to nitrates is also provided. In addition, a discussion on the current state of research and estimated incremental cost to treat for pharmaceuticals in WWTP effluent is presented in Section 12.

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3.0 Review of Basin 162 Hydrology Pahrump Valley (NV hydrographic basin 162) occupies 984 square miles situated in southern Nevada and eastern California (Figure 3-1). The Nevada portion of the hydrographic basin covers 789 square miles (NDWR, 2015 Pumping Inventory). The northwestern Nevada portion of the basin is in Nye County, and includes the Town of Pahrump. The southeastern portion of the basin is in Clark County. The Spring Mountains form the eastern and northern boundary of the basin, rising to an altitude of 11,918 feet amsl. Pahrump Valley is an internally drained basin, with lower altitude ranges bounding to the west, and a valley floor topographic divide with Mesquite (Sandy) Valley to the south. Valley floor elevations range from ~2,500 to 2,800 feet amsl. Precipitation falling on the Spring Mountains, and runoff off from the mountains onto alluvial fans, provides most recharge to valley floor aquifers. Surface water drainage is toward the western side of the basin where playas occupy the lowest part of the valley floor at altitudes near 2,450 feet amsl. The erosional basin-fill materials in the valley are up to 4,800 feet thick, being greatest along structural northwest to southeast troughs the western side of the valley (Harrill, 1986). The Spring Mountains and lower altitude ranges surrounding Pahrump Valley are comprised of complexly faulted and folded Paleozoic sedimentary rocks, including both clastic and carbonate rock types. These rocks underlay the basin-fill materials, and are interpreted to be at least several thousand feet in thickness; the complete stratigraphic section of the Paleozoic sedimentary rocks is 18,000 ft thick (Harrill, 1986). Groundwater occurs in aquifers within the basin-fill materials and carbonate rocks. A shallow water table exists beneath the western valley floor, but underlying aquifer conditions are confined, as evidenced by historical and existing artesian well conditions. Groundwater gradients are westerly, but in northern Pahrump Valley culminate in pumping depressions resulting from domestic, municipal and agricultural pumping at and near the Town of Pahrump. The northwest to southeast trending Stateline Fault system cuts through the western side of the basin, and is postulated to be a partial barrier to groundwater flow. This faulting has evidence of right-lateral movement and is interpreted to be associated with the regional Walker Lane fault system. Other parallel trending faults have been interpreted and postulated to cross the basin in a similar orientation but further to the east. These faults may additionally function as barriers to groundwater flow, and may create compartmentalization of the basin-fill aquifer. Groundwater development in Pahrump Valley commenced in 1913 with the drilling of artesian and pumped wells for irrigation. Groundwater pumping peaked in 1968 at 48,000 AFA, predominately used for agriculture (Harrill, 1986). As agricultural land use transitioned to urban development, pumping has declined to 15,000 - 16,000 AFA in recent years. NDWR 2015 pumping inventory for Pahrump Valley indicates 4,433 AFA pumped from municipal and quasi-

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municipal wells, 561 AFA from commercial wells, 5,520 AFA from 11,040 domestic wells, and 4,477 AFA from agricultural wells, totaling 15,742 AFA. During the prior 7 years, the annual pumping ranged from 13,297 to 18,866 AFA (NDWR, 2015 Pumping Inventory). Groundwater drawdown in the developed portion of Pahrump Valley has ranged from approximately 40 to 80 feet, and current rates of drawdown in the developed area are between 0.5 ft/yr to >1.0 ft/yr (USGS, NWIS data; Klenke, 2017; Giampaoli et al, 2017). Numerous springs once existed near the toe of the coalesced alluvial fans from the Spring Mountains, located roughly near Highway 160. Bennetts (Ivanpah) and Manse springs were the largest springs, with 1916 measured discharges of 4.7 cfs and 3.1 cfs, respectively. Due to development of artesian flowing wells and pumped wells, Bennetts Spring went dry around 1959 and Manse Spring went dry in the 1970s, but has resumed flow, reported at 1.5 to 2.1 cfs in 2011 (USGS, data from NWIS). The resumption of flow coincides with reduced groundwater pumping from the eastern basin-fill in the vicinity of the spring and observed recovery in groundwater elevations.

Figure 3-1 (from Harrill, 1986)

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4.0 Existing Basin Water Balance The hydrogeology of Pahrump Valley has been comprehensively evaluated by several investigators, the most significant of which are Maxey and Robinson (1947), Maxey and Jameson (1948), Malmberg (1969), and Harrill (1986). These investigators defined the hydrogeology and water balances for the basin. Groundwater recharge is principally from the precipitation falling on the Springs Mountains. There is considerable variability and uncertainty in recharge estimates, which range from 22,000 to 37,000 AFA (Malmberg, 1969; Harrill, 1986; Leising, 2015; Rybarski, et al, 2016). Recent modeling by DRI (Rybarski, et al, 2016) utilized a recharge value of 21,600 AFA, determined using the Epstein method (Epstein, et al, 2010). Discharge of groundwater in predevelopment conditions was by springs, phreatophyte vegetation evapotranspiration (ET), and subsurface outflow. Malmberg (1969) estimated the predevelopment ET discharge to be 10,000 AFA, a value similar to the total spring discharge in the valley. Harrill (1986) estimated the predevelopment ET to be 13,000-14,000 AFA, with additional spring ET discharge of 5,200 AFA. Rybarski et al (2016) modeling of Pahrump Valley has 14,000 AFA of combined ET and spring discharge. Deep outflow in the carbonate aquifer has been estimated at 5,000 to 18,000 AFA (Malmberg, 1969; Harrill, 1986). The recent DRI model for the basin simulates 7,600 AFA of deep subsurface outflow (Rybarski, et al, 2016). A great deal of uncertainty exists as to the location and magnitude of this postulated outflow, but it’s presence is supported both by the westward potentiometric gradient and an imbalance in water budget estimates (apparent unaccounted for discharge). The carbonate aquifer outflow may be providing flow to the reach of the Amargosa River between Shoshone and Tecopa (Harrill, 1986). Outflow to Ash Meadows in the Amargosa Desert is not believed to be likely due to the presence of low permeability clastic rocks between the basins (Winograd and Thordarson, 1975). Malmberg (1969), estimated surface outflow in basin-fill sediments to Mesquite (Sandy) Valley of 2,000 AFA (potentially ranging from 1,000 to 4,000 AFA). This outflow however has not been assumed in subsequent evaluations, presumably due to a lack of apparent gradient to south. Based on the work of Malmberg (1969), the potentially capturable discharge from the valley was estimated at 12,000 AFA. The component of deep subsurface outflow was considered not practicably capturable. Given the range in the estimated water budgets, NDWR recently increased the perennial yield for the Pahrump Valley from 12,000 to 20,000 AFA, which presumably assumes some degree of capture of deep subsurface outflow, and/or a water budget more similar to the predevelopment modeling of Harrill (1986). Current Conditions NDWR currently recognizes the perennial yield of the Pahrump basin to be 20,000 AFA, as contrasted with the permitted water rights total of 59,303 AFA (NDWR, April 2017), indicating the basin is over-appropriated. However, not all permitted water rights are pumped. Pumping in

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2015 from permitted water rights is estimated at 10,222 AFA (NDWR, 2015 Pumping Inventory). Domestic wells are exempted from water right permits, and are estimated to pump a total 5,520 AFA, based on an assumed rate of 0.5 AFA per well. Consumptive use of pumped groundwater is not 100% in all cases. Residences with domestic wells commonly have septic systems for wastewater disposal, which return some water to the basin. Estimated septic system return flow is 2,084 AFA. Agriculture also has a portion of applied irrigation water that infiltrates past the root zone and returns to the basin. Using an estimate of 15% return flow, 670 AFA of the 4,476 AF pumped for agriculture in 2015 potentially returned to the basin. The total consumptive use of groundwater in 2015 is estimated at 13,000 AF, of the 15,742 AF estimated to have been pumped. The consumptive use estimated accounts for return flows to the aquifer from WWTP RIBs, and infiltration from re-use irrigation (see Section 8). Pumping is therefore currently considered within the defined perennial yield. However, equilibrium to pumping has not been achieved as reflected in continued water level drawdown in portions of the basin. Groundwater levels have been rising in the eastern portion of the basin, east of Highway 160 in the Manse Spring area and near the toe of the Pahrump fan. But elsewhere in the developed part of the basin, groundwater levels continue to decline (Klenke, 2017; Giampaoli, et al, 2017). This may be indicative of a geographic imbalance in the location of pumping versus the location of available resource (too much pumping distributed in the northern part of the basin), which could be exasperated due to fault barrier compartmentalization of the aquifer (postulated fault associated with the Walker Lane near Highway 160). Groundwater resources in the southern part of the basin are not presently developed to any significant extent, and may need to be developed to harness the perennial yield of the basin. Deep subsurface outflow is also not developed and not likely to be currently affected by basin-fill pumping. Capture of a component of the deep subsurface outflow may be needed to realize the full perennial yield. Lastly, there still exists some ET and spring discharge – principally that of Manse Spring – that can be captured to harness the perennial yield. ET and spring discharges have been substantially reduced. Manse Spring discharges ~1,000 AFA and ET has been reduced to perhaps less than 1,500 AFA. But disequilibrium conditions still exist due to pumping. As drawdown continues, water held in aquifer storage is being withdrawn. The DRI model (Rybarski, et al, 2016) suggests current net storage depletion is ~4,900 AFA. This disequilibrium condition will continue until the discharge from pumping has captured an equivalent magnitude of natural discharge. Unfortunately, equilibrium conditions in Pahrump Valley may not be achieved in the future, particularly if population growth increases the water consumption, and given the difficulty in capturing the deep subsurface outflow portion of the water balance. However, as examined in this study, rates of drawdown in the developed portion of the valley can be curtailed by implementing water resources management strategies that depend on redistribution of pumping and enhancement of recharge. Schematic drawings of predevelopment and current water balances for Pahrump Valley are presented as Figures 4-1 and 4-2. The values provided in these schematics are based on modeling conducted with the DRI model (see Section 5) and results of this study. Table 4-1 summarizes water budget ranges from published studies.

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Figure 4-1: Pre-Development Water Balance Schematic

Table 4-1 – Pahrump Valley Water Balance Ranges from Published Studies

Pre-Development Current Conditions Water Budget Estimates Estimates Parameter (AFA) (AFA) Recharge 21,600 – 37,000 21,600 – 37,000 Spring Discharge 5,700 - 9,800 <1,000 10,000 – 19,200 ET Discharge (inclusive of spring <1,500 discharge sourced ET) Subsurface Outflow* 5,000 – 18,000 5,000 – 18,000 Pumping 0 15,750 Storage Depletion 0 ~5,000 *High variability in subsurface outflow is related to range of the estimated recharge.

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Figure 4-2: Current Conditions Water Balance Schematic *Values derived from the DRI flow model

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5.0 DRI Model Utilization and Limitations In 2016, the Desert Research Institute (DRI) published a calibrated numerical groundwater flow model for the Pahrump Basin (Rybarski, et al, 2016). The modeling simulates pre-development steady-state conditions, and transient (pumped) conditions from 1913 through 2014. Statistically, the model is calibrated to water level elevations and historically observed drawdown sufficiently for use in review of groundwater management strategies. However, during model review, it was noted that the difference between historically observed and simulated spring discharges at Manse and Bennetts Springs was greater than desired. In consultation with DRI, some additional calibration was performed on the steady-state and transient models to improve the spring discharge calibration. This updated version of the DRI model has been used to examine water resources scenarios presented herein. Simulated current (2014) drawdown is shown in Figure 5-1. Simulated total historical drawdown is approximately 50 to 110 feet in the northern part of the valley. Simulated drawdown in the central portion (southern developed area) is approximately 40 to 90 feet. Simulated predevelopment and current water balance parameters are summarized in Table 5-1. Table 5-1 – Water Balance Components in the DRI Model (2017 updated version) 2065 Simulated Pre-Development Current Conditions Simulated Water Conditions with 1.5% Estimates Estimates Budget Parameter Growth (AFA) (AFA) (AFA) Recharge 21,573 21,573 21,573 Spring Discharge 4,727 787 289 Manse Spring 2,329 787 289 Bennetts Spring 2,398 0 0 ET Discharge 10,656 1,177 571 Subsurface Outflow* 6,981 6,813 6,525 Pumping 0 17,672 37,804 Storage Depletion 0 4,874** 23,573** *Lower end of outflow estimate, as currently characterized in the DRI flow model. ** These values are subject to uncertainty in the current model version (compensating errors may be present between pumping and aquifer specific yield)

Fifty years were added to the DRI transient model to simulate future conditions to year 2065. By year 2060, the population in Pahrump is projected to be about 73,000 (Giampaoli, et al, 2017), approximately double the current population, and water demand is predicted at 22,750 AFA. This contrasts with a current consumptive use of groundwater of estimated at 13,000 AFA, which if doubled, would be approximately 26,000 AFA. A simulated pumping growth rate of 1.5% has been used in the 50-year future pumping model, which approximates a doubling of consumptive use of groundwater in the valley. Pumping was increased by 1.5% annually from the current pumping rate in the model without any redistribution of pumping. The doubling of pumping in the model may result in an over-prediction of future

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Figure 5-1 – Simulated Drawdown for Current Conditions and in a 50-year Future Scenario with Population Growth

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pumping, if per capita consumptive water use in Pahrump is reduced from current conditions, or the population growth is not this high. The predicted drawdown in 50 years under this pumping scenario exceeds 200 feet in northern part of the valley, but remains below 100 feet in central part (Figure 5-1, right panel). This indicates that given the current pumping distribution, the northern part of Pahrump is in the greatest imbalance with available water resources, and future rates of drawdown will be approximately 1 foot per year. Conversely, the model suggests that drawdown rates will begin to stabilize in the central part of the valley, without much additional drawdown. The accuracy of this predication should be reviewed carefully, and future model calibration could affect this simulated outcome. If more compartmentalized aquifer conditions exist – such as a fault barrier near Highway 160, then future drawdown in the central part of the valley may be greater than simulated, and continue at rates similar to predicted in northern part. It should be noted that the 2014 pumping (last year represented in the DRI transient model) has a total pumping input of 17,672 AFA, which is greater than the NDWR pumping inventory value of 15,556 AFA, and is without adjustment for return flows. Other years of pumping in the model have not been compared with NDWR pumping inventories values, but should be reviewed. Some adjustment to the simulated pumping magnitude may be necessary, and is expect to necessitate additional calibration of the hydraulic properties in the model, specifically, the specific yield of the basin-fill aquifer. Because the historical drawdown trends are reasonably represented in the model, the utility of the model to make future drawdown predictions is probably sufficient. In order to achieve model calibration to lesser volumes of historically pumped or consumed groundwater, the specific yield of the aquifer will need to be adjusted (lowered) to compensate and achieve a similar match between historical and simulated drawdown. Model calibration to lesser volumes of pumped groundwater will however have bearing on the volumes of groundwater removed from storage, and simulated changes in aquifer storage volumes needs to be treated as preliminary. Based upon our review and use of the DRI model for conceptual review of water resources scenarios in this report, the following recommendations for review and potential updates to the DRI Model are made. 1. Review and if necessary, decrease/adjust historical pumping input in the model to be consistent with NDWR Pumping Inventories. 2. Adjust pumping to reflect consumptive use, to compensate for return flows from agriculture and septic systems – alternatively, add recharge zones to represent these return flows. 3. Examine potential for fault barrier(s) near Highway 160 - determine if a barrier improves calibration. The sharp contrast between declining and recovering water levels documented by Klenke (2017) should be examined as a potential barrier location that causes aquifer compartmentalization. 4. Examine hydraulic conductivity and specific yield distribution and values to potentially achieve improved simulation of historical drawdown and recovery of water levels and

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spring discharges. If historical pumping is adjusted in the model, recalibrate the specific yield values to achieve satisfactory match to historic drawdown. 5. Conduct a sensitivity analysis of recharge magnitude in the model.

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6.0 Re-Distribution of Production Wells

Redistribution of pumping can reduce the rate of observed and predicted drawdown in northern and central Pahrump. It is assumed that redistribution would entail a transfer of existing (and future) municipal pumping to new wells / wellfield locations. The effectiveness of the redistribution concept will necessitate some water system interconnection, and can be improved by future connection of residences on domestic wells to a municipal system, where infrastructure accommodates and there is a willingness to connect. All pumpers would benefit from redistribution, as pressures on the heavily pumped parts of the aquifer will be reduced, and rates of drawdown will be curtailed. For all pumpers (domestic and municipal) future pumping lifts will be less and associated cost to pump will be lower. Also, the future need to deepen wells, or replace wells with deeper wells, will be reduced, which is particularly notable for domestic well owners that have wells that tend to be shallow and will eventually become non-functional (Klenke, 2017). Several redistribution concepts are reviewed herein:

• Shift a portion of northern municipal pumping to the Pahrump fan – east of Highway 160 – simulated at 2000 AFA. • Shift substantial pumping to southern Pahrump Valley (Clark County portion) – three redistribution concepts are reviewed, each at 8000 AFA. o Southern Highway 160 Wellfield o Southern Base of Spring Mountains – Mountain Front Wellfield o Southern Stateline Deep Wellfield

The shift in northern Pahrump pumping to the alluvial fan to the east does not produce much alleviation in magnitude of long-term drawdown predicted for the area (Figure 6-1). None-the- less, some localized relief in simulated drawdown is experienced, and when combined with a flood water detention basin effort (Section 7), provides for more effective groundwater management for northern Pahrump. Potential compartmentalization by postulated fault barriers in the northeastern part of basin (one barrier represented in the model) needs further evaluation, and locations for alluvial fan wells will need to be explored via a drilling program to confirm acceptable conditions for production wells. Agreements with Desert Utilities and Great Basin Util- ities Inc. will need to be established to shift their existing pumping to new alluvial fan wells. Model simulations predict that the southern (Clark County) wellfield shift will be an effective water management strategy in curtailing drawdown in northern and central Pahrump (Figures 6-2 and 6-3). Model simulations assume a uniform reduction in future pumping over the existing developed areas. The redistribution scenarios more effectively spread drawdown geographically over the basin, but do not substantively change the ability to capture the perennial yield. Deep subsurface outflow is not notably reduced by the Highway 160 or the base of the Spring Moun- tains wellfields, over the 50-year simulation period. The Stateline wellfield is simulated to capture 450 AFA of deep subsurface outflow in the 50-year simulation. The DRI model in regards

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Figure 6-1 – Northern Pahrump Alluvial Fan Pumping Redistribution Scenario (2,000 AFA) in 50 years at 1.5% Growth.

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Figure 6-2: Pumping Redistribution Scenarios into Clark County at 8,000 AFA, at 50 years with 1.5% Growth

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Figure 6-3 - Pumping Redistribution Scenario to a Deep Stateline Wellfield

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to magnitude of flow and capture potential for the deep subsurface outflow is uncertain because of insufficient geology and exploratory information on its parameters. The southern pumping redistribution scenarios will need an exploratory drilling program to confirm acceptable production well locations as well as water quality. Transfers of water rights will need to be secured – presumably from existing water rights held for future municipal uses, so agreements with existing utilities will be needed and water rights transfers will need to be approved by the State Engineer. Environmental permitting (NEPA) will be needed to construct the project, providing for power and pipeline corri- dors, and well facilities on public lands. Well depths in the Highway 160 wellfield are not likely to exceed 700-800 feet. Well depths for a base of Spring Mountains wellfield should plan for a deeper water table and for potential production from the underlying carbonate rock aquifer. Well depths of 1,000 to 1,500 feet, or greater, may be needed. Wells at a Stateline wellfield, if desired to be completed into the carbonate rock aquifer, would need to be 3000 feet, or greater, in depth due to the thickness of overlying basin-fill. The basin-fill may also be productive to a shallower well option. A deep well exploration drilling program would be needed to confirm the extents and feasibility to capture the deep carbonate outflow. The 450 AFA estimated capture in this preliminary analysis may be understated per actual conditions. To evaluate the cost versus benefit for re-distribution of pumping, conceptual water facility plans were developed for the shifting of 2,000 AFA in northern Pahrump to the fan, the development of 8,000 AFA of well pumping along Highway 160, and the development of 8,000 AFA of stateline deep well pumping. The base of the spring mountain well field was neglected since it achieved the same level of pumping re-distribution as the Highway 160 well field, but due to the greater distance to install pipelines to Pahrump would result in a higher cost. The cost opinions are limited to anticipated facility construction cost; permitting, lands and water rights (if applicable) are not accounted for, and likely significant in some cases. Facility unit cost information was taken from portions of the GWMP as indicated. The GWMP well development unit costs appear reasonable, while for the proposed pipelines the anticipated working pressures are in excess of 200 psi at many locations, which will dictate metallic materials (ductile iron and/or steel). The $25 per linear foot (included for difficult trenching in GWMP) is assumed for all the pipeline alignments to account for high pressure transmission mains versus PVC mains assumed in the GWMP. The deep Stateline well development cost is estimated from discussion with a well driller with experience in these type of installations (Garth Williams, Drill Tech Inc.). The motor horsepower’s listed are based on assumed pump and motor efficiencies of 80 and 94 percent, respectively. Figure 6-4 identifies the potential water facilities associated with transferring 2,000 AFA (1,240 gpm) from northern and central Pahrump municipal wells to the fan. The proposed well re-locations are to the east, where ground surface elevations increase to the

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(P) Fan Well #1 (P) Fan Dist Storage #1 GS=3,280'+/- 500,000 Gal. Pump El.=2,280'+/- PAD El.=3,280'+/- Flow=310 gpm Head=1,013'+/- HP=125+/- >M8in^ (P) 6-inch Regulator Station El.=3,060'+/-

(P) Flow Control (to CVN tank) 8in or Regulator Station (to distribution)

A (P) 6-inch Regulator Station 45 psi El.=2,930'+/- TU 8in CALVADA 8in A

^ A NORTH 5 TUpsi (P) Fan Dist Storage #2 500,000 Gal. (P) 6-inch Regulator Station PAD El.=3,180'+/- El.=2,950'+/- (P) 6-inch Regulator Station 10in ^ El.=2,825'+/-

8in MA (P) 24-inch Utility Inter-Connect >8in 8in A Backbone Transmission Main 45 psi See SectionDESERT 11 ^8in (P) Fan Well #2 24in TUA UTILITIES GS=2,950'+/- Pump El.=1,950'+/- CALVADA Flow=310 gpm MEADOWS Head=1,190'+/- (P) Flow Control (to DUI tank) HP=150+/- or Regulator Station (to distribution)

(P) Fan Well #3 GS=3,170'+/- Pump El.=2,170'+/- Flow=310 gpm TU Head=1,040'+/- >M HP=125+/- (P) 6-inch Regulator Station El.=2,950'+/- (P) Fan Dist Storage #3

(P) 6-inch Regulator Station 8in 500,000 Gal. El.=2,695'+/- PAD El.=3,180'+/- 8in 10in

A ^ A A

8in (P) Fan Well #4 GS=3,030'+/- (P) 6-inch Regulator Station Pump El.=2,030'+/- El.=2,820'+/- >8inM Flow=310 gpm Head=1,175'+/- HP=150+/- TU MOUNTAIN Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN, and the GIS User Community VIEW TU TU ESTATES

Date: April 2017

Map By: SWB Figure 6-4: Proposed Facilities to Re-Distribute WO#: 16058 2,000 AFA of Pumping to the Fan Scale: 1 inch = 6,000 feet ® A Nye County Water District Pahrump GW Plan Evaluation in June 2017 Regards to Identifying Projects for PER

below ground surface (bgs). The highest proposed well is Fan Well #1 with a ground surface of 3,280-feet, which is approximately 510-feet above the higher Calvada North Tank. Assuming water service connections are to be provided between the proposed Fan well #1 and connection to the Calvada North water system, two pressure regulator stations would be needed (limit service pressures to less than 100 PSI). The regulator stations would be supplied from a proposed 500,000 gallon distribution storage tank located adjacent to the well. The proposed Fan Well #2 is situated within a proposed subdivision (per parcel layout), so in this case a distribution tank may be warranted to the east with an elevation suitable to meet minimum pressure requirements in the subdivision. To maintain maximum working pressures on the order of 100 psi, two to three regulator stations are needed. At the connection to the existing Desert Utility tank, either a flow control valve could be used to supply the tank, or a regulator station to serve customers directly. It is possible to route un-regulated water main around the Desert Utility tank into the proposed 24-inch backbone main described in Section 11, which may be a consideration in a basin-wide water facility plan on how to route-utilize the higher hydraulic grade lines (HGLs) associated with the proposed fan wells. For the proposed Fan Wells 3 & 4 a common tank and related distribution piping is shown, as with the other fan wells the higher HGL warrants the installation of regulator stations to maintain maximum pressures on the order of 100 psi. The total facility cost opinion for the well development, distribution storage/piping, regulator and/or flow control valve stations, and overhead power is on the order of $21.4 million for the facilities shown in Figure 6-4. Once again, the cost opinion does not include, land/easements, permits and water rights.

Table 6-1 : Re-Distribution of 2,000 AFA of Pumping to Fan - Facility Cost Opinion

Description Qty Unit Unit Cost Total Cost Comments Production Wells 4 Each $1,000,000 $4,000,000 Taken from Appendix H of GWMP Assume submersible pumps limited to 150 Well Facilities 4 Each $800,000 $3,200,000 HP+/- 8-inch Pipelines 42300 LF $65 $2,749,500 Taken from Appendix H of GWMP with 10-inch Pipelines 11100 LF $75 $832,500 $25 per foot added for asumed Trenching Distribution Storage 1,500,000 gal $1.25 $1,875,000 3-500K Dist. Tanks at $1.25/gal. Pressure Regulator of Flow 8 Each $150,000 $1,200,000 Control Valve Station Overhead Power 9 Miles $100,000 $930,000 Taken from Appendix H of GWMP Estimated Construction Cost = $14,787,000 Engineering and Inspection $3,696,750 Assume 25% of Construction cost Contingency $2,957,400 Assume 20% of Construction cost Engineering and Contingency = $6,654,150

Total Project Cost Opinion = $21,441,150

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The proposed facilities needed to develop eight (8) production wells along Highway 160 southeast of Pahrump are shown in Figure 6-5. The wells have a target production of 620 gpm each, with a simultaneous production of 5,000 gpm (8,000 AFA). The well locations have a surface elevation ranging from 3,400-feet to 3,520-feet (most southern). For the purposes of estimating well cost, and pump horsepower for a common pumping water elevation of 2,400-feet is assumed. The proposed wells would pump into a common transmission main that parallels Highway 160, and ranges in size from 10-inches to 24- inches. For equalization storage, and to maintain positive pressure at the high point in the transmission main a 1.5-million-gallon terminal storage tank is proposed, with a tank PAD elevation of 3,525-feet±. The proposed tank would be higher than any existing municipal tank in Pahrump, and it is proposed to utilize a flow control valve to modulate flows into the existing Pahrump Utility tank. Conversely, a pressure sustaining valve could be an option to maintain main pressure with a lower elevation terminal tank, but that was not evaluated at this level of analysis and likely not desirable due to the added energy losses. Also, the terminal tank could be used for distribution storage to provide service to the higher elevations on the east side of Highway 160, above the service elevations the existing municipal systems can serve. From the Pahrump Tank (highest current municipal tank), a 24-inch backbone main is proposed in Section 11 that could route up to 5,000 gpm through the central Valley of Pahrump to the Desert Utility system. The capacity of this main is based on the existing HGL of the Pahrump Tank, which if by-passed with a higher pressure main could either reduce the main size needed, or if main size kept at 24-inch increase the capacity with a higher source HGL. The cost opinion for the proposed facilitates shown in Figure 6-5 is provided in Table 6- 2. The total project cost opinion of $46 million does not include permitting, lands, easements and water rights that would need to be obtained prior proceeding with design.

Table 6-2 : Highway 160 Corridor Well Construction Cost Opinion

Description Qty Unit Unit Cost Total Cost Comments Production Wells 8 Each $1,000,000 $8,000,000 Taken from Appendix H of GWMP Well Facilities 8 Each $1,500,000 $12,000,000 Taken from Appendix H of GWMP 10-inch Pipelines 19800 LF $75 $1,485,000 12-inch Pipelines 1200 LF $85 $102,000 Taken from Appendix H of GWMP with 16-inch Pipeline 20000 LF $105 $2,100,000 $25 per foot added for asumed Trenching 18-inch Pipeline 10700 LF $115 $1,230,500 Conditions 24-inch Pipeline 25600 LF $145 $3,712,000 Terminal Tank 1,500,000 gal $1 $1,500,000 Flow Control Valve 1 LS $250,000 $250,000 Overhead Power 13 Miles $100,000 $1,260,000 Taken from Appendix H of GWMP Estimated Construction Cost = $31,639,500 Engineering and Inspection $7,909,875 Assume 25% of Construction cost Contingency $6,327,900 Assume 20% of Construction cost Engineering and Contingency = $14,237,775

Total Project Cost Opinion = $45,877,275

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The proposed facilities to potentially develop 8,000 AFA of deep well field pumping in southern Pahrump Valley, in both Nye and Clark Counties is shown in Figure 6-6. The target production rate of each of the four wells is 1,240 gpm, which may not be achievable depending on the actual pumping water level. The assumed well drill depth is 3,000- feet, with an assumed water level of 2,000-feet (partially artesian) below ground surface. The pumping water level should be more on the order of 500-feet based on the available head from the Spring Mountains, which if this is the case would allow for higher pumping rates. Deep wells are not very common in municipal water systems, they are more common in oil and gas and require specialty pumps-motors and drilling techniques.

Deep well pumps are typically submersibles limited to a total horsepower on the order of 1,000, which at higher flow rates limits the total head accordingly. It is proposed to pump the four wells to a terminal tank, which based on the assumptions listed and proposed well locations would be limited to a PAD elevation of approximate 3,000-feet. If higher pumping levels are realized the well field terminal tank could be located higher, but a more detailed analysis is needed to determine if it can potentially be eliminated with the wells pumping directly to the distribution tank being proposed. To limit pump horsepower to 1,000, the proposed Carbonate Well #1 is limited to pumping 1,800-feet below ground surface, while the remaining three are limited to 2,000 due to their higher surface elevation. The number of wells required will need to be determined based on the exploratory drilling/development, a deeper pumping level will dictate more wells to achieve the same total net production of 8,000 AFA. From the terminal well field tank, a booster station is needed to deliver 5,000 gpm via a 24-inch pipeline to a proposed 500,000 gallon distribution storage tank, similar to the Highway 160 well field option a tank is needed to maintain positive pressures in the high point of the transmission main. From the proposed distribution storage, the water can be routed to service locations on the east of Highway 160, or get regulated into the Pahrump Utility water system.

The facility cost opinion to construct the well field, terminal tank, booster station, distribution storage and pipelines is provided in Table 6-3, and on the order of $66.5 million dollars. Included in the cost opinion is the significant effort anticipated for the geological exploration drilling, geophysics and hydrogeologic effort, 3 to 5 (assumed) million could be required based on drilling effort needed.

A significant concern with this option is the unknowns and expenditures needed to determine if feasible. In addition, the permitting, land/easement and water rights cost are not included.

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Table 6-3 : Carbonate Deep Wellfield 8,000 AFA - Facility Cost Opinion

Description Qty Unit Unit Cost Total Cost Comments Geologic Exploration, Geophysics, 1 LS $5,000,000 $5,000,000 etc.. Permitting, Water Rights and Lands Unkown Unkown Unkown Includes Well Development and Pump Production Wells 4 Each $3,000,000 $12,000,000 Only Well Facilities 4 Each $1,000,000 $4,000,000 Taken from Appendix H of GWMP 12-inch Pipelines 22300 LF $85 $1,895,500 Taken from Appendix H of GWMP with 16-inch Pipelines 22700 LF $105 $2,383,500 $25 per foot added for asumed Trenching 18-inch Pipelines 18300 LF $115 $2,104,500 20-inch Pipelines 18500 LF $125 $2,312,500 24-inch Pipelines 70000 LF $145 $10,150,000 Wellfield Terminal Tank 500000 Gal $1.25 $625,000 Distribution Storage 1,000,000 gal $1.00 $1,000,000 Pressure Regulator of Flow Control 1 Each $150,000 $150,000 Valve Station 1,200 HP Booster Station 1 LS $1,500,000 $1,500,000 Overhead Power 27.3 Miles $100,000 $2,730,000 Taken from Appendix H of GWMP Estimated Construction Cost = $45,851,000 Engineering and Inspection $11,462,750 Assume 25% of Construction cost Contingency $9,170,200 Assume 20% of Construction cost Engineering and Contingency = $20,632,950

Total Project Cost Opinion = $66,483,950

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7.0 Flood Detention Rapid Infiltration Basin Conversion

A rapid infiltration basin (RIB) is an earthen basin designed to promote rapid infiltration and dispersal of water into the subsurface. Rapid infiltration (RI) of waste water treated effluent and industrial discharges has been used successfully in the United States for over 100 years. Depending on site specific characteristic and design, RI can be used for treatment polishing with subsequent subsurface disposal, re-use and/or recharge of aquifers. RIBs utilize repetitive cycles of hydraulic loading, infiltration, and drying. The best soils for RI are coarse textured with high permeability and are one of the predominant factors in site selection. The GWMP recommends investigating the RIB recharge potential in cooperation with Nye County Public Works, and the “Pahrump Regional Flood Control - Master Plan”. Shaw met with NCPW and obtained a copy of the Flood Plan to facilitate this discussion in regards to Pahrump.

The flood master plan (FMP) determined the best solution for the managing flood events in the Pahrump Valley would rely on a system of detention basins to reduce peak and downstream flows. The major storm flows from the Spring Mountain water shed would be intercepted with channels built as part of the eastern beltway project and the Wheeler Wash Dams. The FMP list 43 detention basins with a total volume and area of 15,806 ac-ft and 4300 acres, respectively (Table 7.1), while their locations are shown in Figure 7-1.

Storm water detention basins are designed to reduce the peak runoff by temporarily storing runoff and releasing it slowly over time. Storm water infiltration basins are very similar to detention basins, but are designed to promote more percolation into the ground. Infiltration basins may be slightly larger to account for holding the volume of water for a longer duration and usually include an overflow bypass.

Storm water infiltration trenches and basins are a similar to a RIB, with the primary difference being the source water characteristic and variability in flow. A treated waste water effluent has well defined water quality parameters with flows held relatively constant, while storm water runoff is usually highly variable in both quality and flow. Storm water typically will have the highest contamination load attributed to the “first flush”, which will contribute the majority of the sediment and related maintenance associated with an infiltration basin. The land area for a RIB is based on the design flow rate and soil permeability, while a storm water infiltration basin is sized to store peak runoff flows until it gradually exfiltrates through the soil and eventually into the groundwater table (usually less than 72 hours is required per regulations to mitigate mosquito/vector proliferation). A RIB is less susceptible to sediment loading than a storm water basin. RIBs may utilize underdrains bedded in drain rock to facilitate percolation.

The biggest factor for a successful infiltration basin is site selection. Basins need to be located with sufficient separation from groundwater to prevent mounding, while soils need to be permeable (minimum soil infiltration rates of 0.5 inches/hour). For the purposes of this discussion, eight of the largest proposed detention basins located on the fan where fines content is low relative to the valley are assumed to be suitable for conversion to infiltration basins (see Figure 7-1). The boundary used to approximate the alluvial fan and valley soils is Highway 160, which is shown in the soil maps provided in Appendix B.

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The incremental cost increase to construct an infiltration basin instead of a detention basin is assumed to be 30 percent from review of EPA literature, while the incremental annual maintenance cost increase is on the order of 3 percent of the total construction cost of the basin. The base cost for the detention basin construction was taken from the FMP, with the noted incremental increase in construction and maintenance cost determined in Table 7.1. The incremental costs estimates are very approximate, being perpetuated from previous estimates with factors such as economy of scale, and site specific conditions not being taken into consideration.

The original detention basin cost estimates in Table 7-1 are 2008 dollars, but for the purposes of this discussion no adjustment to present seems warranted. Based on the total basin area of 2018 acres for infiltration basins in Table 7-1, the incremental increase in construction and annual maintenance cost is on the order of $8780/acre and $1,140/acre, respectively.

The incremental increase in construction cost is attributed to more extensive soil investigations and potential over-excavation of impermeable shallow soils, while added pre-treatment and soil stabilization are recommended to reduce sediment loading. Pre-treatment of storm water should be included in the design of an infiltration basin to reduce the annual maintenance and increase the life of the facility. In some cases, pre-treatment is accomplished by sacrificing a portion of the basin volume (20-25 percent) to function as a forebay to settle out solids with provisions for easy maintenance (hard surface to allow sediment removal with a loader). The added maintenance cost is attributed to more inspections to monitor infiltration rates, mitigation of erosion issues contributing to sediment loading and more frequent removal of accumulated sediment and re-grading. The clogging of the top soil layer would require it to be scarified as needed to maintain infiltration rates.

A significant concern for infiltration technologies in the Pahrump Valley is the presence of a caliche layer that will impede water percolating into the aquifer. For the purposes of this discussion, it is assumed that any caliche layers are manageable (shallow depths for easy removal and/or isolated to small areas) for the basin’s noted on the fan, but a geotechnical investigation is needed to make that determination on a case by case basis.

Potential flood detention basin infiltration is estimated at approximately 500 AFA for the eight largest basins indicated in Figure 7-1. Determination of the magnitude of average annual recharge is made by scaling the 100-year peak flows to 2-year and 10-year estimated peak flows using runoff equations developed for southern Nevada (Blakemore, et al, 1997).

Table 7-2 summarizes the estimated volumes of runoff available to the eight selected basins. It is assumed that over the course of 10 years, four 2-year events will occur and one 10-year event will occur. The durations of runoff events were assumed to be ½ day, and 1 day for the 2-year and 10-year events, respectively. Computations indicate that the 10-year runoff events will fill most basins to near capacity. Assuming 70% of the detained runoff effectively becomes recharge, the average annual recharge volume is estimated at 520 AFA. The potential effective-

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Table 7-1: Pahrump Flood Plan – Proposed Detention Basins with Incremental Construction and O&M Cost Increase to Convert a Portion Located on the Fan to Infiltration Basins

Proposed Incremental Incremental Increase Detention Basin Basin Depth, Basin Area, Basin Volume, Basin Infiltration Ownership Cost to Add in Annual ID FT. Acres Ac-Ft Construction Cost Provisions Infiltration Mainteneance Cost

R1700 1.0 12.0 11 No BLM $256,978 $77,093 $10,022 R1900 4.3 17.0 74 No BLM $751,732 $225,520 $29,318 R2150 3.3 311.0 1004 No BLM $8,677,020 $2,603,106 $338,404 R2300 5.0 79.0 389 No BLM $3,435,650 $1,030,695 $133,990 R1850 4.0 24.0 95 No Fee $962,213 $288,664 $37,526 R1750 5.4 35.0 196 No BLM $1,781,887 $534,566 $69,494 R1050 2.0 164.0 294 No Fee $3,096,371 $928,911 $120,758 R350 2.0 41.0 66 No BLM $7,268,264 $2,180,479 $283,462 R200 2.0 35.0 55 No Fee $795,278 $238,583 $31,016 R800 3.0 189.0 545 No BLM $5,021,479 $1,506,444 $195,838 R2000 1.3 48.0 52 No Fee $754,640 $226,392 $29,431 R700 2.7 38.0 99 No Fee $1,062,418 $318,725 $41,434 R2100 2.7 42.0 124 No Fee $1,159,801 $347,940 $45,232 R2200 5.0 66.0 285 No BLM $2,934,468 $880,340 $114,444 R1950 3.0 281.0 848 Yes BLM $7,367,490 $2,210,247 $287,332 R1800 4.0 72.0 273 Yes BLM $2,616,155 $784,846 $102,030 R1550 4.4 427.0 1866 Yes BLM $15,117,137 $4,535,141 $589,568 R1500 3.0 52.0 156 No BLM $1,524,289 $457,287 $59,447 R1650 1.5 40.0 54 No Fee $731,729 $219,519 $28,537 R1600 3.0 14.0 42 No Fee $491,399 $147,420 $19,165 R1250 3.5 23.0 80 No Fee $867,349 $260,205 $33,827 R1150 2.5 48.0 110 No Fee $1,228,960 $368,688 $47,929 R1100 2.5 27.0 115 No Fee $748,190 $224,457 $29,179 R900 3.0 129.0 388 Yes BLM $3,533,194 $1,059,958 $137,795 R650 3.0 207.0 621 Yes BLM $5,472,649 $1,641,795 $213,433 R550 3.0 81.0 229 No Fee $2,279,951 $683,985 $88,918 R150 2.0 21.0 40 No Fee $523,316 $156,995 $20,409 R250 3.0 457.0 1826 Yes BLM $11,642,353 $3,492,706 $454,052 R300 5.0 39.0 202 No Fee $1,880,984 $564,295 $73,358 R500 3.0 172.0 522 Yes BLM $4,644,605 $1,393,381 $181,140 R1000 3.3 238.0 751 No BLM $6,717,677 $2,015,303 $261,989 R100 3.7 273.0 1000 Yes BLM $8,660,054 $2,598,016 $337,742 R600 5.0 75.0 615 No BLM $3,310,560 $993,168 $129,112 R450 4.0 52.0 205 No BLM $1,935,367 $580,610 $75,479 R400 4.0 52.0 205 No BLM $1,935,367 $580,610 $75,479 R1400 2.0 41.0 64 No Fee $908,628 $272,588 $35,436 R750 5.0 35.0 175 No Fee $1,625,338 $487,601 $63,388 R850 5.0 106.0 517 No Fee $4,556,583 $1,366,975 $177,707 R1300 1.7 79.0 1300 No Fee $1,416,398 $424,919 $55,240 R1200 2.5 38.0 90 No Fee $1,002,337 $300,701 $39,091 R1350 1.0 40.0 35 No Fee $573,622 $172,087 $22,371 R950 2.5 80.0 188 No Fee $1,937,907 $581,372 $75,578 Totals all Flood Basins = 4300 15806 $133,207,784 $39,962,335 $5,195,104 Totals for Infiltration 2257 8075 $65,114,502 $19,534,351 $2,539,466 Basins =

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-ness of the basins to infiltrate retained water will differ at each basin site based on soil types and the potential presence or absence of caliche (cemented) strata. Each basin site will need site- specific subsurface investigations to determine concept feasibility. The presence or absence of potential fault barriers to groundwater flow also need to be better understood on the Pahrump alluvial fan, and could have ramifications to storage and recovery of infiltrated water. Geophysical methods such as seismic reflection may aid in identification of fault barriers. This concept does not have a dramatic impact to the level of simulated drawdown in northern and central Pahrump (Figure 7-2), but provides an opportunity to increase the recharge to the valley in the northern area where the greatest imbalance to pumping is present. The flood detention basin AR concept also compliments the Pahrump alluvial fan pumping redistribution concept (Figure 7-3). Therefore, the AR concept could potentially be reasonable to pursue if basins are to be constructed for flood control purposes. The incremental increase in construction and maintenance cost for infiltration provisions is preliminary, but in light of the proposed sizes of the basins sufficient to provide an order of magnitude. Evaluating infiltration basin provisions for development driven storm water projects is recommended, on a smaller scale the additional groundwater recharge could justify the added expense. The estimated incremental increase in construction cost ($19.5 million) when weighed against the added recharge predicted (500 AFA) results in a cost of $39,000 per AFA. Unless the estimated amount of recharge is understated, and/or the incremental increase in construction cost is over stated better options to mitigate the water rights over dedication from a cost benefit are anticipated at this time.

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Table 7-2 – Summary of Flood Control Basins Simulated for AR Infiltration

Estimate Estimate Scaled Scaled of of Peak Drainage Peak Peak Runoff Runoff Basin Basin Basin Detention Flow Area Est Basin Name Drainage Flow Flow 2- Volume Volume Depth, Area Volume Basin ID 100-Yr (sq 10-Yr Yr 10-yr 2-yr (ft) (acres) (AF) (cfs) miles) (cfs) (cfs) Event Event (AF) (AF) North Valley Retention Horseshutem & R250 9818 34.74 1804 94 1790 47 3.0 457.0 1826 Basin Crystal Spring R1550 Wheeler Wash Intercept Wheeler Wash 6103 17.43 1177 63 1167 31 4.4 427.0 1866 South Wood Canyon R100 Carpenter Canyon 4500.0 11.21 895 49 887 24 3.3 311.0 1004 Intercept Alpha Lovers Wash Retention Wood Canyon R1950 4440 10.99 884 48 877 24 3.7 273.0 1000 Basin Spring R650 Horse Springs Basin Lovers Wash 3730 8.54 756 42 750 21 3.0 281.0 848 Santa Cruz Intercept R500 Horse Spring 3198 6.83 658 37 653 18 3.0 207.0 621 Basin Alpha R900 Wheeler North Basin Santa Cruz Spring 3156 6.70 650 36 645 18 3.0 172.0 522 R1800 Wheeler South Intercept Wheeler North 2181 3.92 467 27 463 13 3.0 129.0 388 Totals = 7232 196 Discount 30 Percent = 5062 137 Divide by 10 Years = 506 14 Summation of Both 10 and 2 year Events = 520 AF

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Figure 7-2 – Simulated Drawdown in 50 Years at 1.5% Growth with AR of Stormwater Runoff and Manse Spring Recharge (refer to Section 9)

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Figure 7-3 – Simulated Drawdown in 50 years at 1.5% Growth with Combined Implementation of Flood Detention Basin AR, Manse Spring and 2,000 AFA Pahrump Fan Pumping Redistribution

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8.0 Wastewater Treatment Plant and Individual Sewage Disposal Systems Potential Effluent Return

8.1 Wastewater Treatment Plants In Pahrump, the three major private utilities own and operate five wastewater treatment plants (WWTP’s). Figure 8-1 shows the locations of these facilities. Table 8-1 below identifies the amount of influent that was treated at the WWTP’s in 2016 and the estimated flow per customer. Table 8-1 WWTP Influent Flow and Flow per Customer, 2016 WWTP Annual No. Wastewater Average Influent Customers Flow/Customer, Flow, MG Gallons GBU-Plant #3, Calvada Valley 233.1 3,328 79,465 GBU-Mountain Falls 23.4 (217.7 GPD) GBU-Plant F, Calvada North 7.96 Pahrump Utilities – Jane 1 and 2 36.5 645 56,589 (155.0 GPD) Desert Utilities 12.3 240 51,250 (140.4 GPD) Total 313.26 4,213 74,356 (961 AFA) (203.7 GPD)

The treated effluent at these five facilities is then either infiltrated and/or reused at land application sites. This is illustrated in Table 8-2 below. Table 8-2 WWTP Effluent Disposal, 2016 WWTP Annual Effluent Flow, MG RIB’s Irrigation Reuse GBWC-Plant #3, Calvada n/a 224.4 Valley (Willow Creek and Lakeview Golf course) GBWC-Mountain Falls n/a 26.3 GBWC-Plant F, Calvada North 0.22 7.0 Pahrump Utilities – Jane 1 and 2 36.5 n/a Desert Utilities 12.3 n/a Total 49.0 257.7 (150.4 AFA) (790.9 AFA)

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· GB PLANT F

DESERT UTILITIES

GB PLANT #3

WILLOWCREEK GOLF COURSE

LAKEVIEW GOLF COURSE

PAHRUMP

MOUNTAIN FALLS GOLF COURSE

GB MOUNTAIN FALLS ¤£160

10,000 5,000 0 10,000 20,000 Date: May 2017 Feet Figure 8-1: 0 0.75 1.5 3 4.5 Map By: JH Waste Water Treatment Plant Locations Miles WO#: 16058 Project Contact: Scott Benedict, P.E., Senior Engineer Shaw Engineering Scale: 1 inch = 10,000 feet 20 Vine Street Reno, Nevada 89503 Phone: (775) 329-5559 Nye County Water District Pahrump GW Plan Evaluation in June 2017 Regards to Identifying Projects for PER

A portion of the treated effluent applied to RIB’s is lost to evaporation which is one of the reasons why it is important that RIB’s rapidly infiltrate. For purposes of this Study, an assumed 10% loss to evaporation is assumed to occur in the RIB’s. In regards to irrigation reuse, a minimum amount of infiltration is typically provided in order to manage salinity levels in the root zone within tolerable limits necessary for the plants. Typically, infiltration accounts for 10 to 20 percent of the total water needs. For instance, if the turf ET is 5.5 feet per year, and assuming that 15% of that amount is required for leaching, 0.83 feet of effluent should be allowed to infiltrate through the soil into the underlying groundwater. For purposes of this Study, a 15% leaching fraction was assumed. Return flows to the groundwater resulting from infiltration and land application of treated WWTP effluent are estimated as follows: Estimated Current Return Flows from WWTP’s WWTP RIB’s =135 AFA (150.4-(150.4 x 0.10)) Irrigation =119 AFA (790.9 x 0.15) Total =254.0 AFA Estimated Future Return Flows from WWTP’s Projected Population 30,165 Residences (73,000/2.42 persons/household) ISDS/Domestic Wells 20,900 (12,400 existing + 8,500 future)(See section 8.2) Utility Customers 9,265 (30,165-20,900) Future Wastewater Flow 153 GPD/Customer (assumes 25% reduction to current average of 204 GPD/Household due to future water conservation efforts) Total WWTP Effluent Produced 1,600 AFA ((9,265 x 153=1.42 MGD) The distribution of the treated effluent in the year 2060 to RIB’s or land application sites is not known. Considered the limited water resources in the Pahrump Basin however it is believed that ultimately 100% of the treated effluent will be land applied. Based upon that, the following future return flow was calculated. Total (100% to Land Application) =240 AFA (1,600 x 0.15) Some important elements when considering the use of infiltration basins in Nevada are the following: a. The top 12 inches of an infiltration basin bottom must have a permeability of at least 2.0 inches per hour and there cannot be an impermeable soil layer (< 0.014 inches per hour) within 30 feet of the basin bottom.

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b. The infiltration basin must be located at least 1000 feet away from a water supply well or a surface water. c. The depth to groundwater beneath the basin bottom must be 10 feet or greater. d. There must be at least three monitoring wells (1 upgradient and 2 downgradient) located at the site to ensure that the quality of the groundwater is not being degraded. Important elements related to the reuse of reclaimed water for agricultural and landscape irrigation are the following; a. The reclaimed water (treated WWTP effluent) must meet secondary treatment standards, that is BOD<30 and TSS <30. b. Coliform limits are established dependent upon the method of application (spray or flood) and the buffer zone provided. c. A minimum amount of infiltration is required to maintain salinity levels with the acceptable tolerance limits of the plant. d. No run off from the site or ponding on the site is allowed. e. There must typically be three monitoring wells (1 upgradient and 2 downgradient) located at the site to ensure that the quality of the groundwater is not being degraded. f. The amount of nitrogen contained in the effluent and applied via fertilizers cannot exceed the plant up take rate. g. Storage must be provided during periods when the site cannot be irrigated, or another means of disposal must be provided. Losses from evaporation should be minimized by considering the following; a. Irrigate to meet the crop ET plus the allowance for leaching. Adjust sprinkler systems weekly and seasonally as required. b. Make sure that infiltration basins rapidly infiltrate the water and that standing water is kept to a minimum, c. Irrigate at night. Irrigate when it is calm. Use efficient sprinkler systems, d. Maintain any required storage reservoir volume by increasing the depth and decreasing surface area, and e. Cover storage ponds when possible. 8.2 Individual Sewage Disposal Systems (ISDS) The majority of all ISDS effluent eventually infiltrates back to the groundwater. While State law requires a minimum of a 10 foot separation distance between a leachfield and trees or shrubs, there are certainly cases that exist were shrubs and trees are growing over the leachfield and consuming some effluent. It is also assumed that most leach lines are generally 3 feet or greater in depth so other evapotranspiration is minimal. That being stated, it is assumed that approximately 10 percent is lost due to evapotranspiration. From Table 8-1, a wastewater utility customer in Pahrump contributes anywhere from 140 to 218 GPD/Customer of wastewater influent and averages approximately 204 GPD/Customer. ISDS studies performed within the State of Nevada (Douglas County, Old Washoe, Spanish Springs)

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have utilized values ranging anywhere from 150 to 180 GPD/ISDS. For purposes of this Study, it is assumed that domestic ISDS in Pahrump contributes approximately 170 gallons per day per ISDS and considering assumed evaporation losses, a return value of approximately 150 GPD/ISDS was utilized. Estimates vary slightly on the number of ISDS systems currently in the Pahrump Basin. Nye County has estimated that there are currently approximately 12,400 ISDS systems while Shaw Engineering has estimated that there are approximately 12,600 ISDS systems. Considering that there is the potential for an additional 8,500 future domestic wells in the Pahrump Basin, similarly there is a potential for an additional 8500 future ISDS systems. Based upon the return flows resulting from ISDS and utilizing the County ISDS estimate, the following return flows were estimated:

Estimated Current Return Flows from ISDS=2,084 AFA (12,400 ISDS x 150 GPD/ISDS = 1.86 MGD)

Estimated Future Returned Flows Total from ISDS=3,512 AFA (20,900 ISDS x 150 GPD/ISDS = 3.14 MGD)

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9.0 Aquifer Storage and Recovery and Artificial Recharge

Aquifer storage and recovery (ASR) is the process of routing treated drinking water into the ground through distribution mains that typically terminate at an existing well that is used as the conduit to the ground water table. The water is stored in the aquifer for later use, therefore, providing the recovery component. The allowed percent recovery is not typically 100 percent, and is discounted per field results and regulatory permits. The Truckee Meadows Water Authority (TMWA) in Reno/Sparks Nevada has an ASR program with a recovery percentage on the order of 90 percent, but with the recharge credit not being utilized until after the permitted rights are exhausted, as of today no recharge water has been actually used (on paper). The Las Vegas Valley Water District (LVVWD) has a recharge program with an injection capacity on the order of 100 million gallons per day (MGD), of which approximately 365,000 AF has been injected since 1989. LVVWD also has a mechanism for passive recharge (in lieu credits), in which case groundwater rights not utilized on an annual basis can be banked for the future. The percent recovery for direct injection has not be determined pending negotiations with NDWR, while the in-lieu recovery credit of 85 percent is allowed.

Artificial recharge (AR) is used to enhance the yield of the aquifer by injecting or percolating surface water, imported water, stormwater or treated wastewater. The water is not directly pumped from the same location it is injected the ground water table, and usually requires a buffer from the nearest drinking water sources. The potential recharge of stormwater and treated wastewater for the Pahrump Valley is discussed in sections 7 and 8 of this report. If soil and aquifer conditions permit, and sufficient land area is available the use of recharge ponds (infiltration basins) and spreading basins are generally the most cost effective way to get large quantities of water into the ground (HDR, 2001).

If multiple sources of drinking water are available, such as ground and surface water conjunctive use is a water management strategy that can potentially capitalize the best features of the sources to maximize resource (HDR, 2001). The Pahrump Valley drinking water sources are limited to groundwater, there is no surface water or perennial streams that can be used as a recharge source. Appendix F of the GWMP evaluated the utilization of springs as a recharge source, while this concept was expanded upon in “NCWD Water Supply Appraisal Investigation Report”, prepared by Glorieta Geoscience (2012). These reports can be referred to in regards to the anticipated elements of an ASR project with related cost opinions and assumptions.

In evaluating the groundwater recharge opportunities for Pahrump, the first concept to consider due to its ease of implementation is passive recharge. Passive groundwater recharge is simply the process of resting groundwater wells in areas of declining water levels and offsetting their function as a supply source with alternate resources that do not adversely impact the water levels. In the case of Pahrump, this could be achieved by utilizing fan wells to base load demands and limit valley well pumping to peak demand periods when their capacity is exceeded. From a review of the locations of existing municipal wells in Figure 9-1, there are no distinct fan wells currently in-service. The existing wells are along the approximate location of the transition zone, therefore it is not possible

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CN WELL 1 (34 AFA) Water Wells & Boundary Legend Highway_160 CALVADA APPROXIMATE FAN TO VALLEY TRANSITION NORTH · (V MOUNTAIN FALLS WATERWELLS DU WELL 3 V CALVADA NORTH WATERWELLS DU WELL 2 ( DU WELL 4 (119 AFA)

DU WELL 1 V CALVADA MEADOWS WATERWELLS (142 AFA) ( DESERT UTILITIES V MOUNTAIN VIEW ESTATES WATER WELLS CALVADA (

MEADOWS CM WELL 1 (8 AFA) (V CALVADA VALLEY WATERWELLS (V DESERT UTILITIES WATERWELLS V PAHRUMP UTILITIES WATERWELLS

NOTE: (XX AFA) 2016 WELL USAUGE ACRE FEET ANNUALLY

CV WELL 11 (584 AFA)

MVE WELL CV WELL 9 1 (4 AFA) (281 AFA) CV WELL 1 (417 AFA) MOUNTAIN CV WELL 2 VIEW (525 AFA) ESTATES CALVADA VALLEY CV WELL 8 (513 AFA)

160 ¤£ MF WELL 1 (659 AFA) MF WELL 2 (532 AFA) PUCI WELL 2-OLD HAY FIELD RETIRED PUCI WELL 2

MOUTAIN PUCI WELL 1 (7 AFA) FALLS PUCI WELL 3

PUCI WELL 9 (28 AFA)

PUCI WELL 7 PUCI WELL 3B (1 AFA) PUCI PV WELL PAHRUMP PUCI WELL 8 2 (38 AFA) UTILITIESPUCI WELL 4 (270 AFA) PUCI WELL 5 PUCI PV WELL 1 (2 AFA) PUCI WELL 6

8,000 4,000 0 8,000 16,000 Date: May 2017 Feet Figure 9-1: Existing Municipal Wells 0 0.5 1 2 3 Map By: JH and Miles WO#: 16058 Project Contact: 2016 Production if Utilized Scott Benedict, P.E., Senior Engineer Shaw Engineering Scale: 1 inch = 8,000 feet 20 Vine Street Reno, Nevada 89503 Phone: (775) 329-5559 Nye County Water District Pahrump GW Plan Evaluation in June 2017 Regards to Identifying Projects for PER

to determine with the information currently available if putting certain wells in lead will provide any benefit to the declining water levels in the valley. From meetings with De- sert Utilities Incorporated (DUI) they utilize their well #1 in lead, with well #2 in lag, therefore are using their closet well to the fan first (most eastern). In section 6 of this report, the re-distribution of production wells is discussed and if projects of this nature are realized using these sources to baseload supply with corresponding offsets to pumping in the valley would potentially help balance the basin.

A groundwater recharge strategy that may be more feasible than the previous concepts to utilize spring water for ASR could use the same spring resource, but utilize rapid infiltration basins (RIBs) to recharge the groundwater in an AR project in lieu of underground injection. RIBs are discussed in Sections 7 and 8 of this report. The project would entail capturing the spring outflow and piping it via gravity to a location suitable to install RIBs. The Manse spring is currently being piped to irrigate fields to the west, so in theo- ry the only needed infrastructure could be the construction of the RIBs and related piping to rotate the wetting and drying cycles. Due to the unknown condition of the existing line, for the purposes of capturing potential infrastructure cost it is assumed a new gravity line is needed. The Manse Spring was reported to flow 1.5-2.0 CFS in May of 2011 (USGS, 2011), for the purposes of sizing infrastructure the higher end value is used, while for the potential recharge amount 600 AFA is estimated from groundwater modeling for the 50 year average (see Section 10). The numerical flow model, suggests that Manse Spring discharge persists, but declines over time. Persistence of spring discharge will be dependent on future pumping actions in the valley. It is important to note; the Manse Spring and related water rights are held privately and their potential acquisition and related costs are not included in this report.

As described in the previous reports on utilizing a spring resource for ASR, the first step needed is determining the spring characterization. The spring needs to be evaluated to determine the factors that influence its flow rate, reliability and water quality. The spring discharge rate may be impacted by localized pumping in the basin or climactic factors, and/or a combination of both. The DRI model estimates an average recharge value of 600 AFA over the next 50 years, with this rate sensitive to future pumping levels and water management strategies in the vicinity of the spring.

Based on the information available (lack of site-specific subsurface information including infiltration rates) the existing irrigation fields appear as good a location as any to recharge the basin. The field is located approximately 1.5 miles to the west of the transition zone, and is within the valley basin fill. Assuming the groundwater gradient is to the south- west, this location is upstream of areas with groundwater declines in southern Pahrump on the order of 60-feet (see Appendix C for a figure showing the long-term water level trends in Pahrump Valley taken from the “Draft Nye County Water Resource Plan”, March 2017). The cost-benefit comparison between locating a RIB at the nearby irrigation fields versus adding more miles of mains (14 miles±) to recharge at locations identified in the previous studies warrants further evaluation, which would be facilitated by improvements to the DRI model (see Section 5). The DRI numerical flow model currently suggests the annual spring discharge will decline to approximately 300 AFA in 50

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years, so that is also a consideration in determining the appropriate level of capital investment.

Assuming the location of the existing fields can achieve the needed percolation rates as well as can be acquired from private ownership, the proposed facilities and locations are shown in Figure 9-2. The design flow rate for sizing the gravity pipeline and RIB facility is assumed to be 890 gpm (2.0 cfs). The 10-inch line size was determined based on the elevation difference between Manse Spring (2779-feet) and the surface elevation at proposed RIB location (2711-feet).

The total RIB land area needed is roughly estimated by taking the capacity of the PUCI Jane RIB facility (800,000 gpd) and dividing by the total area estimated from aerial imagery (approximate 3.4 acres). The total area of the RIB facility includes berms and the perimeter maintenance roads, and results in a RIB land area requirement of approximately 235,000 gpd/acre. The Jane RIB facility is located approximately 11,500-feet due south of the proposed RIB location shown in Figure 9-2, so it is reasonable to assume similar soil charecterisitc, but a formal geotechnical investigation will be required prior to design. Based on the 235,000 gpd/acre RIB land area requirement and 890 gpm design flow rate the land needed is approximately 5.5 acres. The cost opinion for project development and physical infrastructure is provided in Table 9-1.

Table 9-1: Cost Opinion to Utilize a RIB to Recharge Manse Spring

Description Qty Unit Unit Cost Total Cost Comments Spring Characterization, RIB Site 1 LS $1,000,000 $1,000,000 Geotechncial and Planning Spring Capture 1 LS $150,000 $150,000 Unit Cost Taken from Appendix H of 10-inch Gravity Line 9,500 LF $75 $712,500 GWMP with $25 per foot added for Pavement RIB Basin Excavation - Export 10,667 Cu. Yds. $3.25 $34,668 Unit Cost Taken from FMP Study RIB Trench-Gravel Placement 3,200 Cu. Yds. $4.0 $12,800 Drain Pipe 1440 LF $100 $144,000 Yard Pipe/Valves 1000 LF $200 $200,000 Perimeter Roads and Security Fence 1 LS $50,000 $50,000 Facility Construction Cost Opinion = $1,303,968 Engineering and Inspection $325,992 Assume 25% of Construction Contingency $260,794 Assume 20% of Construction Engineering and Contingency = $586,785

Total Project Cost Opinion = $1,890,753

The cost for the acquisition of the water rights and spring is unknown, and not included in the cost estimate provided. In addition, lands, permitting and easement cost are not included. The cost for the spring characterization is limited to determining the variability in spring flows and water chemistry to the extent it can be permitted to be recharged into a RIB. Recharging the spring with an RIB located at the surface versus injecting into a well where the water quality needs to meet drinking water standards is anticipated to be less costly. The spring capture component is not anticipated to be significant since

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¤£160

PROPOSED 10-INCH GRAVITY PIPELINE (9,500'+/-)

> ^ PROPOSED RAPID INFILTRATION BASINS (APPROX. 5.5 ACRES) MANSE SPRING SURFACE EL.= 2711' SURFACE EL.= 2779'

Date: May 2017 Map By: JH Figure 9-2: Proposed Water Facilities To Recharge Manse Spring Project Number: 16058 To A Reservoir Scale: 1 inch = 2,000 feet ® Nye County Water District Pahrump GW Plan Evaluation in June 2017 Regards to Identifying Projects for PER

treatment is assumed to not be required to discharge to a RIB, so this could potentially be limited to a distribution box with a rack to screen debris prior to entering the pipeline.

Based on the estimated 50-year average recharge rate of 600 AFA the cost versus benefit is on the order of $3,170 per AFA, plus the cost to obtain the spring, lands and water rights needed. As described in Section 10, it is desirable for Nye County to proceed with this option for the amount of recharge potential as well as obtaining and retiring the senior water rights associated with the spring.

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Section 10- Potential Future Water Balance

The future water balance in Pahrump will be dependent on urban growth rate and the water management strategies that are implemented. The population in Pahrump is projected to be 73,000 by year 2060 (Giampaoli, et al, 2017), which is approximately double the current population. Section 4 of this report examined the current water balance. Pumping from the basin is estimated at approximately 15,700 AFA. Accounting for the consumptive use of groundwater pumped (that portion of pumped water not returned to the groundwater system), consumptive use of groundwater in the basin is approximately 13,000 AFA (Table 10-1). With an anticipated doubling of population in 50 years, it can be assumed that the consumptive use of water will double to approximately 26,000 AFA. Giampaoli, et al (2017) estimate the future water demand for 2060 to be 22,750 AFA, which assumes some degree of water conservation measures can be implemented. Table 10-2 provides a summary of possible future water consumption with conservation efforts to be approximately 19,000 AFA, assuming agricultural water use is reduced to 2,000 AFA, lots permitted for domestic wells are fully developed (8,500 lots), and septic systems off-set a fraction of the domestic well pumping. However, the total pumped would be greater than the total consumed groundwater. The total pumped does not include compensation for the portion returned to the aquifer, and could range from 23,000 AFA to 30,000 AFA.

Table 10-1 - Estimate of Current Consumptive Use of Groundwater

Estimated Consumption Manner of Use Source (AFA) Estimated Pumping minus Septic Domestic Wells 3,436 Return Flows; 5,520 AFA minus 2,084 AFA Use by Non-AG Permits in NDWR Pumping Inventory for 2015; assumed 100% consumptive, less Municipal, Quasi-Municipal, 5,491 the waterwater returned in RIBs and Commercial, Industrial infiltration from used for golf course irrigation (total returned to aquifer of 254 AFA; see Table 10-3) Use by AG assumed 85% consumed of the total pumped from NDWR Agriculture 3,805 Pumping Inventory for 2015 (15% returns to aquifer) Total Estimated Consumptive 13,000 Sum of the above Use (rounded)

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Table 10-2 - Estimate of Possible Consumptive Use of Groundwater by 2060

Estimated Consumption Manner of Use Source (AFA) Estimated Pumping minus Septic Domestic Wells 6,258 Return Flow; 9,970 AFA minus 3,512 AFA, see Table 10-4– Assumed double the current Municipal, Quasi-Municipal, 10,982 consumptive use based on 2060 Commercial, Industrial population projection Assumed 85% consumed of 2000 Agriculture 1,700 AFA remaining in AG (15% returns to aquifer) Total Estimated Consumptive 19,000 Sum of the above Use (rounded)

Water Right Over-Appropriation Pahrump Valley is an over-appropriated basin. Current water right appropriations, including consideration of domestic wells (0.5 AFA per well) is approximately 57,000 AFA. However, this total does not acknowledge senior rights on springs which may have, or will be, impacted by junior groundwater pumping. This is a critical issue to acknowledge and address in the water right commitment assessment, because some of the perennial yield may need to be assigned to spring sources. While this report has not examined the spring issue in Pahrump Valley in detail, Manse and Bennetts Springs were historically two major springs in the basin; both of which have been impacted by pumping. Bennetts Spring went dry in about 1959. Utilities Inc. is the current owner of record of the major rights on the Bennetts spring (Permit 2930, 960 AFA). Preliminary review of existing rights by NDWR indicates that Bennetts Spring should not be counted against the perennial yield (Kelvin Hickenbottom, 2017, personal communication). Manse Spring has resumed flow, but at lower rates than historically observed. Modeling suggests that over the long- term Manse Spring discharge will decline from current flow rate, but this will depend on future pumping and water management actions near the spring. Water rights at Manse Spring are decreed at 2,173 AFA (Vested Claim V02287). Water right ownership is divided amongst members of the Bowman family (1,206.2 AFA), and Utilities Inc. (967.1 AFA). Preliminary review by NDWR indicates that Manse Spring rights should be counted against the perennial yield. Nye County should pursue acquiring the privately-owned Manse Spring water rights to support the AR concept for as long as the spring flows, and if needed, to address the senior priority and future retirement of the rights. The Manse Spring water rights are currently being used for agriculture, and would be subject to a willing seller agreement. If not currently interested in selling the rights, Nye County could pursue an option to purchase the rights in the future (purchase a first right of refusal option), so that when the rights are available for sell, Nye County could be in

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position to acquire the rights. The adjusted water rights commitment, in acknowledgement of mitigation groundwater rights for Manse Spring, is 59,189 AFA, as summarized in Table 10-3. To fully understand the level of over-allocation of water rights, the true consumptive use of water rights needs to be considered. Section 4 of this report reviews the estimated water balance and perennial yield of the Pahrump basin. The estimated over-allocation of water rights is currently 28,200 AFA above the perennial yield 20,000 AFA (Table 10-3). The over-allocation accounts for estimated deductions for water rights to be retired, return flows from waste water (ISDS and WWTPs) as well as the leaching fraction of irrigation. Water rights management strategies include retirement of spring rights to avoid mitigation right appropriations, and continued over-dedication requirements for conversions of water rights from agriculture to municipal. The future over-allocation assuming 3:1 over-dedication requirements, retirement of the Manse springs rights, return flows from ISDS, irrigation re-use credits from WWTPs, and potential credits for proposed artificial recharge (AR) projects is estimated to be 21,700 AFA, as summarized in Table 10-4. Capture of Perennial Yield A critical aspect of water resources management and management of drawdown in the Pahrump Valley, is the capturability of the perennial yield. Some basins in Nevada suffer from ineffective capture of the perennial yield, and resultant long-term drawdown conditions, because the pumping is not geographically positioned in the areas of groundwater discharge. Pumping then will have to remove large volumes of groundwater from aquifer storage as adjustments to capture discharge occur. In some cases, pumping is within the perennial yield, but drawdown cannot achieve a balance with captured discharge. Pahrump Valley exhibits this condition. Pumping is within the perennial yield of 20,000 AFA, being estimated at 15,800 AFA, with a consumptive use of 13,000 AFA, yet regional water level declines persist. Substantial groundwater discharge (ET and spring discharge) has been captured and water levels should be approaching equilibrium – but this is not the case. Over much of the developed part of the basin, groundwater levels are declining at significant rates. The observed water level rises on the east-side of the basin are outweighed by more regionally declining water levels. The groundwater flow model (provisional results) indicates the groundwater storage increase is approximately 3,600 AFA in rising areas, and storage decrease is approximately 8,500 AFA in declining areas. The groundwater system has an overall imbalance of approximately 4,900 AFA to existing pumping. Future calibration adjustments to the model may affect the simulated volumes, but is not expected to change the outcome of a net deficit condition. Pumping from the valley floor is currently not in equilibrium, as indicated by the model and observed declining water levels. Only about 2,000 - 2,500 AFA of natural ET and spring discharge is estimated to remain to be potentially captured from the basin-fill (modeling suggests approximately 1,200 AFA of remaining ET, and 1,000 AFA of Manse Spring discharge). If ET and spring discharge were completely captured, there would still be approximately 3,000 AFA imbalance between the current level of pumping and developed resources. Further complicating

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Table 10-3 – Water Rights Commitments Summary for Current Conditions

Water Rights AFA Source NDWR, April 2017 Basin Summary Minus 1 Committed Underground 51,496 Domestic Well Relinquishments (7,807 AF) NDWR 2015 Pumping Inventory, based on an 2 Domestic Wells (non-permitted) 5,520 estimate of 0.5 AFA pumped per well 3 Subtotal Committed Water Rights with Domestic Wells 57,016 Sum Rows 1 and 2 Needs to be included due to potential for claim for 4 Decreed Right for Manse Spring (Decreed, V02287) 2,173 mitigation rights 5 Subtotal Committed Underground Water Rights with Springs 59,189 Sum Rows 1,2, and 4 6 Over-dedication – Subdivisions 7,085 Per NCWD and Comments Provided by NDWR 7 Adjusted Water Right Commitment 52,104 Row 5 minus 6 8 Unaccounted Septic System Return Flow 2,084 Section 8, this report 9 Treated Wastewater Returned via RIB 135 Section 8, this report Section 8, this report, estimated at 15% of metered 10 Golf Course Irrigation Water Return Flow 119 water use 15% of AG water rights, NDWR April 2017 11 Unaccounted Agricultural Return Flow 1,573 Basin Summary 12 Adjusted Water Right Commitment to Consumptive Use 48,193 Row 7 minus Rows 8 thru 11 13 Perennial Yield 20,000 NDWR, Order 1252 (2015) Net Potential Over-Allocation (rounded) 28,200 Row 12 minus 13

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Table 10-4 – Water Rights Commitments Estimate for Future Conditions (2065)

Water Rights AFA Source NDWR, April 2017 Basin Summary Minus Domestic 1 Committed Underground 51,496 Well Relinquishments (7,807 AF) NDWR 2015 Domestic Well estimate plus 8,500 2 Domestic Wells (non-permitted) 9,770 additional lots to be developed, based on current parcels; and an estimate of 0.5 AFA pumped per well Needs to be included due to potential for claim for 3 Decreed Right for Manse Spring (Potential Mitigation Right) 2,173 mitigation rights 4 Subtotal Committed Underground Water Rights with Springs 63,439 Sum Rows 1 to 3 NCWD/NDWR estimate of current subdivision over- dedication of 7,085 AF plus additional relinquished 5 Over-dedication – Subdivisions and Domestic Wells 12,775 of 5,690 AF – conversion of AG AF) to M&I at 3:1; with 2000 AF remaining in AG 6 Adjusted Water Right Commitment 50,664 Row 4 minus 5 7 Unaccounted Septic System Return Flow 3,512 Section 8, this report 15% of AG water rights, assuming 2000 AF remains 8 Unaccounted Agricultural Return Flow 300 in AG 9 Adjusted Water Right Commitment to Consumptive Use 46,852 Row 6 minus the sum of 7 and 8 Section 8, this report – all WWTP effluent pump to 10 Potential Reuse Credit 1,600 use for urban landscaping Section 8, this report, 15% of water used for 11 Potential Return Flow Credit from Reuse 240 irrigation 12 Potential AR Recharge Credit for Flood Control Basins 500 Section 7, this report 13 Potential AR Credit for Manse Spring (50-year average) 600 Section 9, this report 14 Retirement of Manse Spring Rights 2,173 To remove mitigation right appropriation or claim Adjusted Water Right Commitment to Consumptive Use plus Water 15 41,739 Row 9 minus the sum of 10 thru 14 Resources Management Strategies 16 Perennial Yield 20,000 NDWR, Order 1252 (2015) Net Potential Over-Allocation (rounded) 21,700 Row 15 minus 16

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the picture is anticipated population growth and necessity to pump and consume greater volumes of water, which will exasperate the imbalance causing higher rates of storage depletion and accelerating water level declines. The reason that continued drawdown is simulated, even though the recharge volume in the model is approximately 22,000 AFA, is that some of the groundwater flow and perennial yield is occurring in the deep carbonate rock aquifer. Pumping from the basin-fill cannot effectively capture the deep outflow component. One modeled scenario – a deep well scenario near the Stateline – does capture some of this outflow, but modeling suggests that this component of the perennial yield will be difficult to capture. The result is that from a sustainable pumping perspective – the sustainable yield of the basin-fill aquifer in northern and central Pahrump is nearer to 10,000 AFA - 12,000 AFA, as estimated by Malmberg (1969). To reiterate, the sustainable yield is the magnitude of pumping, from the presently developed basin-fill aquifer, that can result in equilibrated water level conditions. This magnitude of sustainable perennial yield from the basin-fill aquifer is substantially supported by observations of current levels of drawdown over much of the basin, with little remaining natural groundwater discharge by ET and spring discharge to be captured, and occurring when pumping consumption is only 13,000 AFA. If the perennial yield from the basin-fill were greater, then there would be either 1) greater remaining ET and spring discharge to capture – justifying continued drawdown, or 2) net equilibrated (stable, non-declining) pumping water levels. Figure 10-1 shows the simulated drawdown in 50 years at a 1.5% growth rate (approximate doubling of existing pumping), with the implementation of several long-term water resources management actions reviewed in this study, including AR of floodwater and Manse Spring discharge, reallocation of 2,000 AFA of pumping to the Pahrump alluvial fan, and redistribution of 8,000 AFA of pumping to a wellfield in the southern part of the valley (Highway 160 wellfield option). Figure 10-2 shows the predicted drawdown difference in 50 years for the actions identified in Figure 10-1 compared to the no-action scenario. Figure 10-3 illustrates the difference in predicted drawdown achieved by these water resources management actions at a location in the central-portion of the community of Pahrump. Continued drawdown however still occurs in portions of developed areas of Pahrump Valley. To the degree that per capita water use can be reduced by conservation measure the amount of pumping and corresponding drawdowns may be less than currently predicted in the modeling simulations. The implications of no-action are that water levels will continue to decline at rates that will result in failing domestic wells. It should be noted that the drawdown rates assumed by Klenke (2017) are based on historically observed rates, and do not factor into consideration increased pumping to support population growth. Klenke (2017) estimated that 18-57% of the domestic wells will fail in 50 years. This rate of failure could be greater if growth and increases in pumping occur, as expected. Using an inflation-adjusted average cost to replace a dry well of approximately $27,000

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Figure 10-1 – Simulated Drawdown in 50 year at 1.5% Growth with Combined Stormwater and Manse Spring Recharge, Pahrump Fan Pumping Redistribution, and Southern Highway 160 Wellfield Pumping Redistribution.

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Figure 10-2 – Simulated Difference in Drawdown in 50 Years with the No Action Scenario for 1.5% Growth with AR and Pumping Redistribution to Highway 160 Wellfield

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Figure 10-3 – Simulated Drawdown for No Action with 1.5% Growth, and with AR and Pumping Redistribution to Highway 160 Wellfield

per well, the cost to the community to replace domestic wells over the next 50 years could range from $80,000,000 to $135,000,000. This estimate assumes the following:

• 3,000 to 5,000 domestic well failures occur due to declining water levels over the next 50 years, • A current cost for a replacement well of $15,000, inclusive of costs for drilling a new well to 100 feet deeper than the current well, plugging the old well in accordance with state regulations, resetting the pump approximately 100 feet deeper, and reconnection of power and plumbing to the new well. • An inflation rate of 2.2%, based on the 20-year U.S. national average. This is a very preliminary estimate of community costs, and does not take into consideration natural deterioration and well replacement needs, regardless of if water levels are maintained. A more sophisticated examination is warranted to take this evaluation and cost estimate to the next level of review. Use of the flow model (with updated calibration for pumping and specific yield; and a potentially more refined future pumping schedule) in combination with the domestic well

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database compiled by Klenke (2017) could provide for a more rigorous determination of numbers and timing of expected domestic well failures due to declining water levels. Water management strategies reviewed in this report, particularly the reallocation of 8,000 AFA of pumping to the southern part of the basin or the Stateline, have the potential to lessen this cost, but would probably not eliminate the costs, as drawdown is predicted to continue in some parts of the basin (but at slower rates). It should be noted that the wellfield pumping rate of 8,000 AFA selected for the pumping reallocation analysis in this report is arbitrary, and was selected as a magnitude similar to the current aquifer storage depletion occurring in the areas of declining water levels, as suggested in the current version of the model. Changing the pumping reallocated quantity, or progressively introducing greater reallocation pumping, will change the outcome of predicted future drawdown, or lack thereof. Not quantified in this analysis is the potential benefit to the community from implementation of a major water management project by lessening pumping costs (less electrical power), and as it relates to avoidance of community conflict and litigation. Implemented water management strategies are presumed would be funded by a regional assessment, distributing costs amongst all water users. Under a no-action scenario, select individuals that have the misfortune of a failing well will bear disproportionate costs associated with continued regional drawdown. This will undoubtedly lead to conflict and future litigation, as observed in other areas with similar problems. Case-action law suits are certainly possible, but one issue that can be expected, is litigation related to real estate transactions, when a new property owner has purchased a residence that experiences a failing well that he/she feels was not properly disclosed during the real estate transaction. Of final note, the modeling of water management options in this report are simulated to commence in year 2020. Delay in implementing the water management actions would result in less effective curtailment of drawdown and greater predicted impacts over the 50-year period.

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11.0 Backbone Infrastructure and Create Incentives to Voluntarily Connect to Public Water Systems.

There are three private utility companies within the Pahrump Valley that include a total of seven separate water systems, approximate system boundaries are shown in Figure 9-1. Private utility companies are regulated by the Public Utility Commission of Nevada (PUCN), which promotes the policy that growth must pay for itself, not existing rate pay- ers. The DWR has expressed support for the inter-connection of utilities as a potential means to reduce the proliferation of new wells to better manage the limited groundwater resource.

As can be seen in Figure 11-1, there are a substantial amount domestic wells within the retail boundaries of the water utilities. The number of domestic wells within the retail boundary of an existing utility service territory is on the order of 1,260, the domestic well mapping was provided by Klenke (January 2017), where they are located to the nearest ¼ by ¼ section. The buildable land area outside of the water utilities retail boundary is expansive, there are currently 11,000 lots with domestic wells and another 8,500 lots designated for a well.

The “Water and Sewer System 2017 Integrated Resource Plan”, prepared by the Pahrump Division of the GBWC proposes projects stated to support the health of Basin 162, with a primary goal to benefit the Community. Section 4.5 of the GBWC report identifies the need for a Backbone Infrastructure Study Project. As part of this study, one objective shall be to identify how many future domestic wells would be reduced by putting backbone infrastructure, and/or community wells at targeted locations within their retail boundary. Due to Homeland security concerns as well as potential disclosure of confi- dential access to utility planned growth, detailed infrastructure and operational data was limited. The lack of detailed information prevented a targeted backbone planning analysis within the effort anticipated, therefor this discussion is limited to a high-level interconnect plan that is summarized below. Potentially in conjunction with the NCWD, the GBWC study could be expanded to include areas outside of their service territory as well as coordination with other utility projects to maximize capital investment.

The scope proposed in the GBWC backbone study is to collect data and coordinate future developer service plans with existing, and future domestic well locations. The goal would be to route infrastructure to achieve the largest overall benefit, serve the planned growth, while also capturing as many domestic well conversions and new municipal hook ups as possible. The GBWC’s proposed Calvada Meadows project listed in their 2017 IRP is proposing water infrastructure extensions to an area of future growth to mitigate the proliferation of domestic wells, which may likely result due to individual hardship for them to connect individually.

Elsewhere in the 2017 GBWC report it is proposed to implement tariff changes to promote voluntarily utility connections. The report proposes connection fee forgiveness, and both utility and Community participation in line extensions. The stated goals are to sup-

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TU CALVADA TU NORTH

Existing Desert Utilities Tank Pad=2,684' +/-

DESERT TU UTILITIES CALVADA MEADOWS

TU Proposed 24'' Inter-Connecting Transmission Main ~24 miles (5000 gpm capacity, South to North)

Proposed Inter-Connections to GBWC TU TU TU CALVADA VALLEY

# MOUTAIN TU FALLS TU PAHRUMP UTILITIES TU TU

Legend TU Water Tanks

Domestic Wells Existing Pahrump Utilities Tank NOTE: Domestic wells shown are stacked in some cases, Pad=2,980' +/- mapped to nearest 1/4' x 1/4' section

Date: April 6th, 2017 Figure 11-1 Existing Domestic Wells, Municipal Water Map By: SWB/JH System Boundaries with Proposed 24-Inch WO: 16058 Transmission Main Inter-Connect Scale: 1 inch = 10,000 feet ® Nye County Water District Pahrump GW Plan Evaluation in June 2017 Regards to Identifying Projects for PER

port the health of the basins limited water resource, and to some extent are analogous to main rehabilitations to repair leaks, with the common goal being to meet customer needs and maximize efficiency.

The GBWC 2017 Integrated Resource Plan will be subject to hearings with the PUCN this summer, and potentially into Fall 2017. To some extent, the rulings could be a measuring stick for gauging the PUCN’s opinion on where the cost of resource management are to be drawn in cases such as Basin 162.

Backbone Infrastructure Discussion:

The existing water systems have service elevations that range from 2575-feet (low point in Calvada Valley system) to 2915-feet (high point in Pahrump system), while they are spatially separated by miles. The approximate elevation and hydraulic grade lines (HGLs) for each water system is provided in Table 11-1, based on an assumed 100 psi pressure at the low elevation, and 40 psi at the high elevation. The elevations were taken from reviewing the contours against the existing retail boundaries, and are just intended to provide a frame of reference between systems.

Table 11-1: Existing Water System Approxiamte Service Elevation Ranges

Approximate Low Approximalty High Approximate Approximate Water System Service Elevation, Ft. Service Elevation, Ft. Low HGL, FT. High HGL, Ft. Pahrump Utility Company 2650 2915 2881 2996 Mountain Falls 2670 2815 2901 2896 Calvada Valley 2567 2890 2798 2971 Calvada Meadows 2610 2750 2841 2831 Desert Utility 2588 2670 2819 2751 Calvada North 2623 2800 2854 2881 Mountain View Estates 2576 2578 2807 2659

The elevation differences between the existing systems do not appear significant (north- south), therefore inter-connecting the existing pressure zones is not anticipated to require significant pumping and/or regulation. The water systems are generally located north- south along Highway 160 as they evolved from the existing agricultural wells installed near the transition zone. The topography of the Valley is generally sloping from the east (higher elevations) to the west, so with the water systems occupying the similar elevation ranges (north-south) the majority of cost to interconnect systems will likely be transmission mains. For the purpose of sizing and providing a cost estimate for infrastructure, a transmission main with a capacity on the order of 5,000 gpm (8,000 AFA) from the highest tank in the Pahrump water system (PAD elevation = 2,980-feet±) to the Desert Utility 200K gallon tank (PAD elevation = 2,684-feet ±) is shown in Figure 11.1. Based on the elevation difference between the two tank PADs of 296-feet+/-, approximately 24 miles of main length and the design flow of 5,000 gpm, a 24-inch diameter pipeline would be needed (refer to Figure 11-1). The main size will allow for 5,000 gpm of gravity flow from the Pahrump system to the Desert Utility tank, areas along the alignment in the low-

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er western portion will have pressures in excess of 100 psi and require regulation prior to service. Assuming similar main cost as provided in the “Pahrump Water Importation – Preliminary Cost Estimates” contained in Appendix H of the GWMP, a price of $145 per linear foot is assumed for construction, with the total project cost summarized in Table 11-2.

Table 11-2: 24-inch Valley-Utility Inter-Connect Transmission Main Cost Opinion

Description Qty Unit Unit Cost Total Cost Comments 24-inch Transmission Main 125000 LF $145 $18,125,000 Unit Cost Taken from GWMP Total Construction Cost Estimates = $18,125,000 Engineering and Inspection $4,531,250 Assume 25% of Construction Contingency $3,625,000 Assume 20% of Construction Engineering and Contingency = $8,156,250

Total Project Cost Opinion = $26,281,250

The proposed backbone transmission main could potentially accomplish the following:

 Inter-connect existing utilities for added reliability.  Serve existing and future domestic well lots.  Facilitate routing of re-distributed well pumping from the south throughout the Valley (refer to Section 6).  Route recharge water to areas of declining groundwater levels for injection.

As noted in the January 2017 Klenke report, the domestic well data is mapped to the nearest ¼ by ¼ section, which may have locational errors up to 933 feet. Mapping the physical location of the domestic wells appears needed to better estimate the cost/benefit for main extension versus well conversions, as well as supporting other efforts in groundwater studies.

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12.0 Wastewater Treatment Plant and Individual Sewage Disposal Systems Water Quality Considerations

12.1 Wastewater Treatment Plant Infiltration basins and agricultural/landscape irrigation have been historically and successfully used throughout the Country including the State of Nevada. These effluent disposal systems provide a means of disposal, groundwater recharge, and lessens the burden from aquifer pumping that would otherwise be required for irrigation. Generally, infiltration basins and land application of effluent are preferred effluent disposal methods over discharge to surface waters due to lower costs and increased public acceptance. In Nevada, NDEP regulates and approves all infiltration and land application of effluent from WWTP’s and closely monitors the groundwater quality passing through these sites to ensure that there is no degradation occurring. Additional treatment of the effluent is achieved as the water percolates though the soils via filtration, chemical processes (adsorption, ion exchange, precipitation), and microbial action. Phosphorous and most metals are retained in the soil. In the case of agricultural/landscape irrigation, additional nutrients, such as nitrogen and phosphorous, are also removed through plant uptake. A typical concern with all infiltration and land application sites is nitrate contamination to the underlying aquifer resulting from nitrogen contained in the effluent. Nitrate has been a concern for many years in the Pahrump Basin and various sampling programs undertaken. Nitrate also occurs naturally in groundwater aquifers and can also be attributable to farming practices (i.e. the application of nitrogen fertilizers). Elevated levels of nitrate above natural background levels is typically attributed to wastewater and/or farming. This discussion focuses on the wastewater component. Nitrogen is found in all raw municipal wastewater typically ranging in concentrations from 30 to 50 mg/l. Nitrogen can be successfully lowered at wastewater treatment plants (WWTP) if the WWTP was specifically designed for nitrogen removal though a process known as nitrification/denitrification. Nitrogen is also removed naturally to varying degrees in the soil and from plant uptake. Nitrogen in the soil will be converted through natural processes to nitrate and then nitrite. Nitrate can easily be transported through the soil into the underlying aquifer. The concentration of nitrate in the underlying aquifer is very dependent on many factors a discussion of which is beyond the scope of this Study. Excessive amounts of nitrate can cause methemoglobinemia (commonly called blue baby syndrome). As a result, nitrate is regulated as a primary drinking water standard and is set at 10 mg/L by the USEPA. All of the WWTP’s in Pahrump are required by NDEP to lower the total nitrogen to less than 10 mg/l. The 10 mg/l standard has been established to prevent nitrate levels in the underlying aquifer from reaching 10 mg/l (drinking water standard). Table 12-1 illustrates the average total nitrogen

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concentrations from the three largest utilities in Pahrump. As can be seen from the Table 12-1, all the utilities are successfully removing total nitrogen in all cases too well below the limits set by NDEP. Table 12-1 WWTP Effluent Total Nitrogen Discharged WWTP Permit Limit Effluent Total Annual Nitrogen Nitrogen Discharged in Concentration 2016 2016, mg/L (lbs) Plant #3, Calvada Yes (TN<10 2.00 3,743 Valley mg/l) Mountain Falls Yes (TN<10 0.41 90 mg/l) Plant F, Calvada North Yes (TN<10 4.29 258 mg/l) Pahrump Utilities Yes (TN<10 3.67 1,117 mg/l) Desert Utilities Yes (nitrate < 2.69 276 10 mg/l) Total 5,484

The water quality of the underlying aquifer at the infiltration and land application sites is monitored via groundwater monitoring wells specifically established for each site. Any degradation of water quality resulting from the effluent would require that the WWTP take appropriate action. NDEP specifically requires certain actions as a result of an increase in nitrate concentrations up to an including immediate ceasing of the discharge should the nitrate reach 9 mg/L. Oftentimes the effluent can improve the underlying aquifer water quality. This has been demonstrated, for instance, at the Pahrump Utilities WWTP where the nitrate concentration decreases as the groundwater passes under the infiltration site. In regards to irrigation reuse, a properly managed program will monitor nitrogen applications such that the needs of the plant are satisfied. With the lower amount of total nitrogen contained in the WWTP effluent, supplemental fertilizer application would be anticipated to be required to maintain healthy plants. Care must be exercised to not over fertilize at these sites. NDEP requires annual nitrogen balance calculations to ensure that these sites are not over fertilized. It is important that effluent infiltrates rapidly, whether at an infiltration site or for land application. An infiltration basin that is allowed to accumulate water increases evaporation (which decreases the recharge potential) which then concentrates chemicals increasing the risk to underling groundwater aquifers. In addition, basins that are allowed to have standing water will lose their infiltrative capacity over time. In order to maintain the infiltration capacity of an RIB, as well as its treatment effectiveness by maintaining and aerobic environment, it must be allowed to dry between loadings.

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12.2 Individual Sewage Disposal Systems Individual Sewage Disposal Systems (ISDS) are common in Pahrump and have been estimated by Nye County to number approximately 12,400 with an additional 8,500 ISDS projected in the future. Domestic ISDS systems are not regulated by NDEP. There presently is no regulatory mandated monitoring program to monitor the impacts, if any, that ISDS have on the underlying aquifer with the exception of larger commercial ISDS. ISDS systems provide primary treatment, that is, the only treatment provided occurs through settling in the septic tank and that which can be accomplished in the leachfield. Similar to rapid infiltration and land application systems utilized by WWTP’s, additional treatment of the ISDS primary effluent is achieved as it percolates though the soils via filtration, chemical processes (adsorption, ion exchange, precipitation), and microbial action. Also similar to infiltration and land application systems, nitrogen is a concern with ISDS systems. Very little nitrogen, if any, is removed in an ordinary ISDS system. Nitrogen typically in the form of ammonia can convert to nitrate which can easily percolate to the underlying aquifer. Figure 12-1 graphically illustrates this. Some natural nitrogen removal occurs in these systems through various natural mechanisms, typically in the 10% to 20% removal range. The estimated amount of total nitrogen currently discharged into the environment from ISDS systems is shown in Table 12-2 below.

Table 12-2 Estimated ISDS Effluent Total Nitrogen Discharged Flow/ISDS Effluent Total Annual Nitrogen Nitrogen Discharged Concentration, (lbs/year) mg/L 1.86 MGD (150 40 12,400 ISDS Systems 226,481 GPD/ISDS) (Typical is 30-50) (2,084 AFA)

A simplified example is provided as a means of understanding the impact ISDS systems could have on an underlying aquifer. Question: What will the total nitrogen concentration increase to if 2,084 acre feet of ISDS effluent with a total nitrogen concentration of 40 mg/l were added to 12,000 acre feet of water with a background total nitrogen concentration of 5 mg/l? Answer: The total nitrogen concentration would increase from 5 mg/l to 10.2 mg/l.

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Based upon Table 12-2 and the example provided, the amount of nitrogen being added to the environment through the ISDS contribution is not an insignificant quantity and certainly has the potential to increase nitrogen levels in the underlying aquifer.

Figure 12-1: Septic System (ISDS) Schematic Nitrate contamination resulting from ISDS systems and/or past farming practices have occurred. In Nevada, nitrate contamination has occurred in Douglas County (Johnson Lane), Washoe County (Spanish Springs), Humboldt County (Grass Valley), and Elko County (Spring Creek). In some instances construction of wastewater treatment plants and/or wastewater collection systems were necessary. ISDS systems in Pahrump are certainly contributing nitrate to the underlying aquifer, the impacts of which have yet to be fully understood. Each individual well owner who is also on an ISDS, should sample their well water for nitrate on a routine basis. There are ISDS systems that can remove nitrogen from the wastewater. These systems are basically mini-WWTP’s that must be operated and maintained just like any other WWTP, albeit on a smaller scale. These systems typically cost $10,000 to $20,000 per ISDS to install dependent upon site specific conditions and are estimated to cost approximately $1,200/year to operate and maintain. For 12,400 ISDS, and assuming a $15,000/ISDS average cost to construct, the total estimated cost to retrofit all of the existing ISDS is $186 million with an annual O&M cost of approximately $15 million. The typical homeowner is not usually qualified, or has the interest, to properly operate these treatment systems and oftentimes they simply do not work and their effectiveness quickly

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becomes questionable. Construction of centralized collection systems and WWTP’s to serve the more densely populated ISDS areas is the preferred approach and could very well be necessary in the future. 12.3 Pharmaceuticals Pharmaceuticals have received a fair amount of attention recently and continues to remain on the radar screen of industry professionals. There is much information available on the subject some factual, some unproven. Much research on the subject continues with special attention being given to long term exposure to low levels of pharmaceuticals and combined effects of mixtures of pharmaceuticals. Much of the information presented herein is primarily based upon a Report prepared by the World Health Organization (WHO) in 2012 that was financially and technically supported by the USEPA. The WHO is an agency that is well respected throughout the world. Trace levels (nanograms to low micrograms per liter range) of pharmaceuticals have been found in surface waters, wastewater, groundwater, and drinking water. Based upon clinical studies utilized to assess the efficacy and safety of all pharmaceutical drugs, acceptable daily intake dosages (ADI) and minimum therapeutic doses (MTD) have been determined for each drug. By comparing the actual levels of drugs measured in the environment, it was found that the exposure rate relative to the MTD is extremely low, in many cases 1000 fold below the MTD. Conventional wastewater treatment plants have demonstrated significant removal of pharmaceuticals however removal rates have been found to vary within and between studies. Pharmaceutical removal rates within ISDS systems have been far less studied and are therefore less understood. Per Section 8, municipal wastewater treatment plants in Pahrump currently introduce approximately 941 AFA of treated effluent into the environment while ISDS systems are estimated to contribute 2,084 AFA. Advanced wastewater treatment facilities that consist of membrane technology have shown higher removal efficiencies, some as high as 100%. Conventional water treatment facilities provided mixed results. Coagulation and filtration processes did little, however chlorination was found to oxidize approximately ½ of the pharmaceuticals. Advanced water treatment technologies, such as reverse osmosis were demonstrated to achieve rates in excess of 99% removal. Little data presently exists on removal rates from ISDS systems but it is assumed removal efficiencies will also vary. Even advanced treatment technologies, let alone ISDS systems, will not be able to remove pharmaceuticals below what can be detected therefore it is important to understand the toxicological significance of the various compounds in the context of risks posed to humans. There are currently no drinking water standards for pharmaceuticals. It is believed that there are far more significant toxicological and microbial risks deserving attention than those posed by pharmaceuticals. The recommendations of the WHO Report, re-printed in its entirety, is as follows:

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“Trace quantities of pharmaceuticals in drinking-water are very unlikely to pose risks to human health because of the substantial MOE or margin of safety between the concentrations detected and the concentrations likely to evoke a pharmacological effect.

Concerns over pharmaceuticals should not divert the attention and valuable resources of water suppliers and regulators from the various bacterial, viral and protozoan waterborne pathogens and other chemical priorities, such as lead and arsenic.

The current levels of exposure to pharmaceuticals in drinking-water also suggest that the development of formal guideline values for pharmaceuticals in the WHO Guidelines for Drinking- Water quality is unwarranted.

Routing monitoring of pharmaceuticals in water sources and drinking-water at the national level and the installation of specialized drinking-water treatment infrastructure to reduce the very low concentrations of pharmaceuticals in drinking-water are not currently deemed necessary given the limited additional health benefits. However, where specific circumstances, such as a catchment survey, indicate a potential for elevated concentrations of pharmaceuticals in the water cycle (surface water, groundwater, wastewater effluent and drinking-water), relevant stakeholders could undertake targeted, well-designed and quality-controlled investigative studies to obtain more information to assess potential health risks arising from exposure through drinking water. If necessary, screening values could be developed and an assessment of the need for treatment enhancement could also be considered within the context of other risks and priorities using the water safety plan.

Human exposure to pharmaceuticals through drinking-water can be reduced through a combination of preventive measures, such as take-back programs, regulations, public guidance and consumer education to encourage the proper disposal of unwanted pharmaceuticals and minimize the introduction of pharmaceuticals into the environment.

Enhanced risk communication to the public and public education efforts on water quality issues from the human health standpoint will help the public to better understand this issue relative to other hazards, such as pathogenic microbial risks. This means conveying the risks of exposure to very low concentrations of pharmaceuticals in drinking-water to the public using plan language.”

The estimated cost to remove pharmaceuticals from the wastewater is difficult to assess because it is uncertain what the levels would need to be reduced to and what treatment process would be able to achieve those levels. Dependent upon the specific drug, multiple treatment approaches may be required. It can only be assumed at this time that reverse osmosis (RO) has the ability to reduce the pharmaceutical concentrations to some acceptable level, whatever that is. RO treatment is energy intensive and not water efficient. RO treatment has recovery rates on the order of 60-80%. A 60% recovery means that for every 100 gallons of water sent through RO treatment, only 60 gallons are treated and the remaining 40 gallons are wasted and must be disposed of. The quality of secondary denitrified effluent leaving any of the existing WWTP’s in Pahrump would have to be improved before it could be subsequently treated with RO in order for the RO

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membrane to work. It is envisioned that some type of filtration (ultrafiltration or microfiltration) would be required to precede the RO treatment. The capital costs to add filtration and reverse osmosis can vary greatly ranging from an estimated $10/gallon to $20/gallon or more. The operation and maintenances cost also vary ranging from $1 to $2 per 1000 gallons or more. For purposes of this Study, it was assumed the capital cost is $15/gallon and the O&M costs are $1.50 per 1000 gallons. Based upon these numbers Table 12- 3 below estimates the total cost at each of the five wastewater treatment plants to add filtration and reverse osmosis as well as the annual amount of water lost based upon 70% recovery rate.

Table 12-3 Estimated Cost to Add Filtration and Reverse Osmosis and Water Lost WWTP Plant Capacity, Capital Cost Annual Annual MGD (Million) O&M Cost Water Lost (AFA) (Million) (AFA) Plant #3, Calvada Valley 1.5 $22.5 $0.8 M 720 Mountain Falls 0.75 $11.3 $0.4 M 360 Plant F, Calvada North 0.050 $0.8 0.03 M 24 Pahrump Utilities 0.80 $12.0 $0.4 M 384 Desert Utilities 0.175 $2.6 $0.1 M 84

As can be seen, these costs are high as are the water losses and considering the lack of any clear evidence that reducing pharmaceuticals will have any positive effect on human health it does not seem warranted, or even feasible, to pursue the removal of pharmaceuticals.

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13.0 Conclusions and Recommendations

The primary goal of this investigation was to identify physical infrastructure projects that support the GWMP that can be prioritized from the standpoint of cost versus benefit. The projects evaluated should either increase the sustainable yield, or enhance the capturability of the perennial yield. To accomplish the stated goal, this report focused on two main areas in regards to groundwater management of Pahrump Basin 162:

• Groundwater recharge • Re-distribution of pumping

A secondary objective was to review potential water quality concerns with regards to individual sewage disposal systems (ISDS), and the treatment for pharmaceuticals at the municipal waste water treatment plants (WWTP).

To achieve the level of understanding needed on the hydrogeology as well as provide a means to quantify benefits of various projects, the DRI groundwater model was utilized (refer to Section 5). The DRI model required added refinement, after which it was able to allow for a conceptual review of water resources scenarios. The DRI groundwater model has limitations in its present state, which it is recommended to reconcile with further updates that are beyond the scope of this investigation.

The potential artificial recharge (AR) projects evaluated included utilizing stormwater infiltration basins in-conjunction with the Nye County Flood Master Plan (see Section 7), and spring capture and routing to a rapid infiltration basin (see Section 9). From review of current municipal well locations passive recharge was not deemed currently possible to mitigate groundwater declines in the valley floor, while with only groundwater sources available conjunctive-use is not an option.

The annual recharge from incorporating eight infiltration basin’s into the NCPW Flood Master Plan is estimated at 500 AFA, while the potential recharge credit for capturing and recharging Manse Spring is on the order of 600 AFA (50-year average). The cost of physical infrastructure per AFA of estimated artificial recharge is provided in Table 13-1. The cost estimate for the infiltration basins is limited to the incremental increase in cost to convert a proposed detention basin in the FMP to an infiltration basin. The cost estimate to recharge Manse Spring is limited to spring characterization and facility construction cost; the cost of permitting, lands, easements, spring acquisition and water rights is not included.

Table 13-1: Cost per AFA for Artificial Recharge of Stormwater and Manse Spring

Estimated Facility Artificial Recharge Facility Cost per AFA Construction Cost Estimate, AFA Infiltration Basins $19,500,000 500 $39,000 Manse Spring $1,900,000 600 $3,170

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Return flows from existing and future (2060) WWTP effluent is estimated at 254 AFA and 240 AFA, respectively (see Section 8). The existing estimate includes return from RIBs and irrigation re-use infiltration, while for the future estimate it is assumed 100 percent of WWTP effluent will be land applied, therefor only a fraction (assumed at 15%) of the higher flows will be returned via land application infiltration. The estimated current and 2060 groundwater return from ISDS is 2,084 AFA and 3,512 AFA, respectively.

The Pahrump Basin is similar to many basins in Nevada that suffer from the ineffective capture of the perennial yield due to pumping not being geographically located in areas of groundwater discharge. From a pumping perspective, the sustainable yield of the basin- fill aquifer may be on the order of 10,000 AFA – 12,000 AFA. At current pumping levels, it is estimated the storage depletion in Basin 162 is 5,000 AFA. Pahrump has the added constraint of having a portion of the perennial yield occurring as deep carbonate rock aquifer outflow, which as conveyed in this report is likely very difficult to capture. Re- distribution of pumping was evaluated for the following three scenarios, with related facility cost developed on a conceptual level (see Section 6):

• Shift 2,000 AFA of municipal pumping from northern-central Pahrump to the east (alluvial fan). • Shift 8,000 AFA of basin-wide pumping southeast of Pahrump along Highway 160. • Shift 8,000 AFA of basin-wide pumping south of Pahrump to a Stateline deep well field. The scenario evaluated predicted a capture of approximately 454 AFA from the deep carbonate aquifer.

The shifting of 2,000 AFA of municipal pumping to the eastern alluvial fan did not produce much alleviation in predicted Valley drawdown, but potentially coupled with the proposed flood infiltration basins provides benefit to groundwater levels in northern Pahrump. For the purposes of quantifying the infrastructure cost associated with shifting wells to the fan, conceptual water facility plans and corresponding cost estimates are provided (see Section 6). The monetary benefit for pursuing this option is difficult to quantify, but the qualitative benefits appear to be:

• Serve future development on the eastern side of Highway 160. o Potentially tie the development of alluvial fan wells to Developer annexation agreements. • Develop sources with a higher hydraulic grade line (HGL) that can be used to supply upper elevations as well as reduce main sizes needed to serve lower elevations. • Added system reliability.

The proposed development of 8,000 AFA of pumping along Highway 160 was deemed an effective means to curtail drawdown throughout Pahrump. This scenario achieves a more global drawdown geographically, but does not substantially change the ability to capture the perennial yield. The 8,000 AFA of deep Stateline well fields had a predicted capture

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of 450 AFA of carbonate outflow, but with the current unknowns and corresponding limitations of groundwater flow model this may be understated. Due to the water resource issues facing Pahrump, it is recommended to conduct the geophysics necessary and pursue deep well exploration of the carbonate aquifer to determine its extents and ability to capture.

A potential option to reduce the cost of developing the Stateline wellfield and help justify from cost-benefit would be to construct these wells after, or in conjunction with the Highway 160 wellfield project. The concept would utilize a common transmission main for the portion that parallels Highway 160 as well as the same distribution storage tank (see Figures 6-5 and 6-6) to lower total facility cost. A Stateline wellfield option at some level appears needed to capture the upper limit of the perennial yield, so it warrants further scrutiny. Pending well exploration, planning and lands research the optimal resource/facility plan could likely be a combination of the Highway 160 well field and a Stateline Deep wellfield.

The facility cost opinion for the development of the Highway 160 well field is $46 million, and would likely require a backbone transmission project similar to what is proposed in Section 11 for distributing the 8,000 AFA throughout the Valley. The total facility cost estimate to develop the Highway 160 well field and backbone transmission main is on the order of $72 million (does not include cost for permitting, lands/easements and water rights).

The current cost to deepen a domestic well is on the order of $15,000, so assuming a range of 3,000 to 5,000 domestic wells need to be deepened by 2060 the corresponding cost range is $45 to $75 million. Assuming the added energy costs for pumping basin wide with a deeper groundwater table is offset by the operation and maintenance (O&M) cost associated with the Highway 160 wellfield facilities, the overall cost between pursuing the Highway 160 option and deepening 5,000 domestic wells are roughly equivalent. The level of analysis is conceptual, and to better determine the cost to the community it is recommended to utilize the DRI flow model in combination with the improving upon the domestic well database compiled by Klenke (2017) to locate wells to their corresponding parcels.

The development of the Highway 160 wellfield would reduce the number of well failures and pumping cost in the future, but not likely eliminate them as drawdown is still predicted albeit at a lower rate compared to the no action alternative. The root of the problem with the re-distribution of pumping options not being able to eliminate drawdown is the sustainable yield of the basin-fill aquifer is estimated to be on the order of 10,000 –12,000 AFA (see Section 10). The difference between the 20,000 AFA perennial yield established by NDWR and the sustainable pumping perennial yield is debatable, and due to the criticality of this topic it is recommended to better define this value with additional groundwater modeling and exploration of the deep carbonate aquifer.

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The water quality considerations of the future Pahrump groundwater conditions in regards to nitrate is deemed a potential concern that warrants further study. The current annual nitrogen discharged from ISDS is estimated at 227,000 pounds per year, which has the potential to increase nitrate levels in the aquifer (see Section 12). It is recommended that nitrate sampling be implemented basin wide to evaluate their levels by location. Sampling can help identify areas that may potentially need mitigation in the future, and the sooner this information is obtained prior to elevated levels the more able mitigation can be planned and implemented cost-effectively. Also, the treatment of pharmaceuticals in WWTP effluent was researched and discussed in Section 12 of this report. At this time, our conclusion on pharmaceuticals is the health risk is not deemed significant enough to justify the added cost for treatment to remove.

The net potential over allocation of water rights commitment in the future with assumed credits for over-dedications, re-use (WWTP used for all irrigation), WWTP return flow (infiltration from irrigation), artificial recharge for stormwater and Manse Spring, and retirement of spring rights is 21,700 ac-ft (see Table 10-4). This value is not conservative, but based on the projects identified in this report being implemented as well as the purchase and retirement of existing spring rights privately held. The reality of the situation is that there is a significant lack of resource for commitments, and based on the likelihood that a portion of the 20,000 AFA perennial yield may not be feasible to capture exacerbates the situation.

The conceptual backbone transmission main that could deliver 5,000 gpm (8,000 AFA) from Pahrump Utilities (south Pahrump) to Desert Utilities (north Pahrump) was evaluated in Section 11. The proposed main alignment is through areas with high densities of existing and proposed domestic wells, which could promote conversions and reduce their proliferation. The main was sized to route up to 8,000 AFA of water from southern re-distribution of well pumping, which would need a means to get routed throughout the Valley. If the re-distribution of wells to the south does not get realized and/or at a lower value than 8,000 AFA, the transmission main size and related cost would be lower.

Pending investigations into nitrate levels and potential mitigation if warranted, it may be prudent to develop a Valley wide plan that jointly constructs water transmission mains, and a sanitary sewer collection system targeted at both domestic wells and septic (ISDS) conversions to municipal. The urbanization of Pahrump Valley and potential consolidation of utilities are topics beyond the scope of this study, but in all likelihood future steps that may be required to support added growth from both a water resource and quality perspective.

In summary, the following actions are currently recommended in regards to the groundwater management of Pahrump Basin 162:

1. A nitrate sampling program is recommended to determine if elevated levels of nitrate are occurring. The sampling previously conducted should be expanded upon to provide conclusive results and further define the areas of concern

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(Nye County Water Resource Plan Update, April 2017). Due to the potential threat to public health from nitrates in groundwater this is deemed an essential task. 2. The purchase of the Manse Springs water rights by Nye County is in the best interest of the groundwater users in Basin 162, and it is a recommended near term-action to initiate negotiations on their acquisition. If the spring and rights can be purchased, then at that time it is recommended to proceed with the planning, design and construction of a rapid infiltration basin (RIB) project to recharge the Manse Spring to the Valley basin fill. 3. Refine the Desert Research Institute (DRI) ground water model to the level needed to better predict cause and effects reactions of water resource strategies. This will allow for better monetary quantification of benefits from proposed projects. Once developed to the extent needed, the groundwater model can be used for predictive water quality modeling, which may be beneficial in the evaluation of nitrate transport throughout Pahrump Valley. 4. As recommended by Klenke (2017) and concurred in this report, the physical location of domestic wells should be mapped to the parcel it is located on. This will allow more accurate determination of well failures from water level declines, in addition to aiding in coordinating municipal transmission mains installations with potential domestic well conversions. Also, as part of this effort septic tanks (ISDS) should be located to its corresponding parcel to potentially aid future studies on water quality issues associated with nitrates. 6,798 of 9,774 wells are mapped to an assessor parcel number (Klenke, 2017), so in conjunction with Nye County GIS it could be a matter of backing out the clean matched data then utilizing aerial imagery and physical investigations to reconcile the remaining records. Also, improved mapping of domestic wells coupled with the DRI flow model will better quantify the cost to the community for future well failures, which is important when evaluating the cost-benefit of potential projects such as the Highway 160 wellfield. 5. Due to water resource deficiency in Basin 162 it is recommended to explore the extents, and ability to capture the deep carbonate outflow. The cost to conduct the geophysics, exploratory drilling and hydrogeologic effort is anticipated to be on the order of $3 to $5 million, depending on the extent of drilling required. The transfer of the water rights needed and permitting could be another $1 to $2 million (assumes no water rights purchase needed). The permitting and ability to transfer the water rights needs to be investigated to the level necessary to determine overall project feasibility prior to implementing an exploratory well program. The goal would be to capture an additional 6,000 AFA to 8,000 AFA to help sustain water levels in the future. 6. The Highway 160 wellfield should be further refined, potentially in- conjunction with a Stateline deep wellfield. As stated in 4 above, better information on the predicted number of future domestic well failures will allow for a better cost-benefit comparison. 7. It is recommended to install infiltration basins at locations detention basins are being proposed if the soil permeability and depth to groundwater supports their application. Infiltration basin’s require added cost for pre-treatment and

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maintenance, but they will support the goals of the GWMP and being multifaceted projects additional funding sources are possible.

The nitrate sampling is deemed an essential task due to the potential risk to public health, and it should be prioritized accordingly. It is recommended the NCWD develop an Action Plan that further prioritizes items 2 through 5 based on total project cost, critical milestones, and level of feasibility in light of budget and overall community goals. Items 6 and 7 should be considered as opportunities arise to implement. In the case of the Highway 160 well field, if Stateline wells are developed the potential for common facilities could potentially reduce cost to justify implementation of a portion of these wells. Utilizing infiltration basins instead of detention basins should be evaluated with site specific information that will provide a more accurate assessment of cost and corresponding benefits.

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14.0 References

Berger, D.L., Ross, Hydrogeology and simulated effects of urban development on water W.C., Thodal, C.E., resources of Spanish Springs Valley, Washoe County, west-central Nevada, and Robeldo, A.R., USGS Water-Resources Investigations Report 96-4297. 1997

CASQA, 2003 California Stormwater Quality Association, Infiltration Basin – California Stormwater BMP Handbook Excerpt, January 2003

DRI, 2016 Rybarski, S., Rajagopal, S., Pohll, G. And Pohlmann, K., Modeling Assessment of Pahrump Valley, Nevada, Desert Research Institute, December 2016. EPA, 1984 U.S. Environmental Protection Agency, Process Design Manual for Land Treatment of Municipal Wasterwater – Supplement on Rapid Infiltration and Overland Flow, October 1984.

EPA, 2006 U.S. Environmental Protection Agency, Process Design Manual Land Treatment of Municipal Wastewater Effluents, Land Remediation and Pollution Control Division, September 2006.

Farr West Engineering, Nye County Engineering Evaluation of Pahrump Utility Company, Inc. 2012 First Draft, August, 2012

Giampoli, et al, 2017 Giampaoli, M., C., TerraSpectra, Jamieson Geological, 2017, Nye County Water Resources Plan Update, Draft March 2017.

GGI, 2013 Glorieta Geoscience, Inc., Assessment of Selected Springs and Wells in the Pahrump Valley and Western Spring Mountains, Nye County, Nevada, Nye County Nuclear Waste Repository Office, February 2013.

GGI, 2013a Glorieta Geoscience, Inc., BEC Environmental, Inc., Nye County Water District Water Supply Appraisal Investigation Report, Nye County Water District, September 9, 2013.

GBWC et. al, 2017 Great Basin Water Co., Valentine Environmental Engineers Inc., , Great Basin Water Co. Pahrump Division Water and Sewer System 2017 Integrated Resource Plan, February 28, 2017.

GWMP, 2015 Nye County Water District Staff, Pahrump Basin 162 Groundwater Management Plan, Groundwater Management Plan Advisory Committee, October 16, 2005.

Harrill, 1986 Harrill, J.R., Ground-Water Storage Depletion in Pahrump Valley, Nevada- California, 1962-75, Division of Water Resources, U.S. Geological Survey Water-Supply Paper 2279, 1986.

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HDR Engineering, HDR Engineering, Handbook of Public Water Systems, 2nd Edition, John 2001 Wiley & Sons, 2001.

HDR Engineering, HDR Engineering, Treatment Technology Review Assessment, 2013 Association of Washington Business/Cities/Counties, December 4, 2013.

Klenke, 2017 Klenke, Estimated Effects of Water Level Declines in the Pahrump Valley on Water Well Longevity, Nye County Water District, 2017

Leising, 2015 Leising, J.F., Hydraulic, Hydrostatigraphic and Climate Assessment of the Pahrump Groundwater Basin, Leising Geoscience, December 2015.

Malmberg, 1967 Malmberg, T., Glen: Geology from Hydrology of the Valley-Fill and Carbonate-Rock Reservoirs Pahrump Valley, Nevada-California, U.S Geological Survey Water Supply Paper 1832, Plate 1 (dated 1963), 1967

Maxey and Jameson, 1948 Geology and water resources of Las Vegas, Pahrump, and 1948, Maxey, G.B., and Indian Spring Valleys, Clark and Nye Counties, Nevada: Nevada Jameson, C.H., Water Resources Bulletin 5, 292 p.

Maxey and Jameson, Maxey, G.B., and Robinson, T.W., 1947, Ground water in Las 1947, Maxey, G.B., and Vegas, Pahrump, and Indian Spring Valleys, Nevada (a summary): Jameson, C.H., Nevada State Engineer, Water Resources Bulletin 6, 23 p.

NDEP, 1993 Nevada Department of Environmental Protection, Design Criteria for Septic Tanks and Individual Disposal Systems-WTS-22, April 1993, revised October 2002.

NDEP, 1993 Nevada Department of Environmental Protection, Guidance Document for an Application for Rapid Infiltration Basins-WTS-3, March 30, 1993.

NDWR, 2015 Nevada Division of Water Resources, State Engineer, Pahrump Valley (Hydrographic Basin 10-162) Groundwater Pumpage Inventory, Calendar Year 2015

Naranjo, R.C., Welborn, The Distribution and Modeling of Nitrate Transport in the Carson Valley T.L., and Rosen, M.R., Alluvial Aquifer, Douglas County, Nevada, USGS Scientific 2013 Investigations Report 2013-5136.

PRPC, 2014 Pahrump Reginal Planning Commission, Pahrump Reginal Planning District Master Plan Update 2014, Nye County Board of County Commissioners, Adopted December 2014.

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Rybarski et al., Rybarski, S., S. Rajagopal, G Pohll, and K. Pullman, Modeling Assessment of Pahrump Valley, Nevada, Division of Hydrologic Sciences Technical Report, 10p., Desert Research Institute, 2016.

UDEQ, 2010 Utah Department of Environmental Quality Division of Water Quality, Utah Guidance for Constructing Rapid Infiltration Basins (RIBs), December 2010

UICN, 2014 Utilities, Inc. of Central Nevada, Valentine Environmental Engineers, Utilities, Inc. of Central Nevada Water and Sewer System 2014 Integrated Resource Plan, February 28, 2014. UNESCO, 2005 United Nations Educational, Scientific and Cultural Organization, Strategies for Managed Aquifer Recharge (MAR) in semi-arid Areas, 2005.

Winograd and Hydrogeologic and hydrochemical framework, south-central Great Thordarson, 1975 Basin, Nevada-California, with special reference to the Nevada Test Site, USGS Professional Paper 712-C

Zhan, H. and W.A. An assessment of nitrate occurrence and transport n Washoe Valley, McKay, 1998 Nevada: Environmental & Engineering Geoscience, vol. 4, no. 4, p.479- 789

Phone Interviews and Research:

1. Christian Kropf, Truckee Meadows Water Authority (TMWA) Hydrogeologist. Phone: 775-834-8016. TMWA groundwater recharge information.

2. Jim Prieur, Las Vegas Valley Water District (LVVWD) Hydrogeologist. Phone: 702- 862-7437. LVVWD groundwater recharge information.

3. Russ Weigart, El Dorado County Public Works. Phone: 530-573-7224. Stormwater detention/infiltration basin planning/cost discussion.

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Appendix A

“Pahrump Basin 162 Groundwater Management Plan – Stage One”, October 16, 2016 (less Appendices)

Pahrump Basin 162 Groundwater Management Plan

STAGE ONE Version Oct. 16, 2015

Prepared for: Groundwater Management Plan Advisory Committee

Prepared by: NCWD Staff and GWMPC Members

1 | Page

Table of Contents: Page: CHAPTER 1 – INTRODUCTION…………………………………………………………………………………………………4 (A) - Background (B) - Basin 162 Groundwater Management Plan Advisory Committee (C) - Acronyms Used in This Report

CHAPTER 2 - BASIC PAHRUMP BASIN WATER RESOURCES FACTS AND FIGURES ……………………6 (A) - Perennial Yield vs Permitted Water Rights (B) - Over Dedication of Water Rights (C) - Domestic Well Usage Estimates (D) - Potential Groundwater Withdrawal Overdraft (E) - Potential Offset to the Over Allocation Figure (F) - Projected Total Usage at Build-out

CHAPTER 3 - HISTORY AND REFERENCE TO STATUTE(S) ………………………………………………………12 (A) - Historical Reports and State Engineer Orders (B) - Statutes and Regulations Governing the Division of Water Resources (C) - Nye County Code and Water Resources in the Pahrump Basin

CHAPTER 4 –PAHRUMP BASIN HYDROLOGY CONSIDERATIONS ………………………………………… 14 (A) - Water Level Measurement Program (B) - Redistribution of Production Wells (C) - Use of Groundwater Flow Models as Planning Tools

CHAPTER 5 - RECOMMENDATIONS FROM THE GROUND WATER MANAGEMENT PLAN COMMITTEE…………………………………………………………………………………………………..18 (A) - Aggressive Water Education (B) - Adopt a Water Conservation Plan (C) - Water Importation to Pahrump (D) - Require Meters on New Domestic Wells and Limit New Domestic Well Usage to 0.5 AFA (E) - Educate New Domestic Well Owners on Supplemental Water Rights for Usage >0.5 AFA (F) - Construct Rapid Infiltration Basins (G) - Aquifer Storage and Recovery (H) - Allow Utilities to put in Backbone Infrastructure (I) - Create Incentives to Voluntarily Connect to Public Water Systems (J) - Conservation Credit Program (K) - Development Agreements (L) - Growth Control (M) - Additional Recommendations

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List of Tables Page:

Table 1a - Underground Water Rights Permitted by Manner of Use..…….………………………………6 Table 1b - Basin 162 Pumpage by Manner of Use ………….…………………………………….………………. 6

Table 2 - Perennial Yield of 20,000 AF versus Potential Groundwater Withdrawal..……………… 8 Table 3 - Adjustment of Over-Allocation by Crediting Reuse, RIB Recharge and Over-Dedication of Water Rights..………………………………………………………………………… 9 Table 4 - Water Usage by Population at Different Gallons Per Capita Per Day (gcpd) Rates.…32

List of Figures

Figure 1 - Density of Domestic Wells in Pahrump per Square Mile……………………………………… 11 Figure 2 - Distribution of wells monitored as part of the WLMP ………………………………….……… 15 Figure 3 - 10 year Water Level Change Map…………………………………………………………………………16

List of Appendices Appendix A - WDGB Resolution to Require Relinquishment of Water Rights for Future Development Appendix B - Water Level Measurement Program - Hydrographs for the Pahrump Basin Appendix C - Water Supply for the Future of Southern Nevada – 1970 Report Appendix D - Order 1252 from the State Engineer Appendix E - Information Regarding Interconnection of Utility Infrastructure Appendix F - Report on Aquifer Storage and Recovery Appendix G - Recommended Plant List for the GWMP Conservation Plan Appendix H - Report on Water Importation to Pahrump Appendix I - Information Regarding the Domestic Well Credit (County Code, NRS and Explanation) Appendix J - Pahrump Master Plan Update Water-Related Policies Appendix K - GWMP Workshop Ideas Appendix L - Nye County Population Estimates (2nd Quarter 2015) Appendix M - Groundwater Pumpage Inventory (2013) and Hydrographic Area Summary (2015) Appendix N - All Orders from the Division of Water Resources Regarding the Pahrump Basin Appendix O - AB 419 – Provisions Relating to Ground Water Basins Appendix P - Pahrump Valley Water Resources Management (2012) Appendix Q - Excerpts from the Water Supply Appraisal Investigation Report (2013) Appendix R – Nevada Water Law 101

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CHAPTER 1 – INTRODUCTION

(A) - Background

In 2011 the Nevada State Legislature passed into law Assembly Bill 419. Part of AB 419 language references the submittal and approval (by the State Engineer) of a Ground Water Management Plan. Components of the plan would be tailored to represent present and future conditions for a particular basin, which is to say: Each basin is unique in character such as available water supply versus present and future demands, physical geologic and lithologic conditions, available lands for development, existing population and growth potential, types of uses, permitted water rights, domestic well density, production well locations, water utility availability, economic factors and other conditions. Components of the plan could include a variety of actions and/or state and local regulations to have groundwater withdrawals in step with available groundwater supply.

The Pahrump Hydrographic Basin is one of the most over appropriated basins in Nevada and has the highest density of domestic wells of any basin in the State. In addition, the community of Pahrump has available deeded lands in sufficient amount to support a population of 495,000. The published basin Perennial Yield of 20,000 Acre Feet could support a population of approximately 80,000 using the overall goal of198 gallons per person/per day adopted in the 2014 Pahrump Master Plan (18,000 AFA), with the remaining Perennial Yield plus re-use waters and future recharge credits available for irrigation.

Note: Utilities presently doing business in the Pahrump basin estimate average household usage within their service areas at a range of 278 to 300 gallons per day/per household (300 gal/day/household = 0.33 AFA). Using 300 gallons/day at 2.42 people per household calculates to 124 *gpcd (this includes outdoor use). DWR estimates Domestic well use at 0.5 AFA. Using the same 2.42 people per household this calculates to 184 gpcd for those households on a domestic well. All of the above estimates include both indoor and outdoor uses. (gpcd is Gallons Per Capita Day and is simply what each person uses in gallons per day)

Overall community gpcd calculations include commercial, industrial, construction water and other uses, but exclude irrigation in the calculation. Using the 2013 pumpage inventory of 14,348 AF, less irrigation of 3,466 AF divided by a current population of 38,929, this calculates to a current 250 gpcd overall for the community of Pahrump.

(B) – Basin 162 Groundwater Management Plan Advisory Committee

To address the issue of over appropriation the Nye County Board of Commissioners, in concert with the Division of Water Resources, formed an advisory committee in Jan. 2014 to make recommendations for a Ground Water Management Plan. The Committee’s mission statement is: “To create an equitable groundwater management plan for the Pahrump Basin and the Pahrump Community that balances water supply and demand today and for the future”.

This committee has met one to two times monthly from Jan. 2014 to present (Sept. 2015) to discuss the over allocation of the basin, hold public meetings and workshops, consider options, collect information and make recommendations for a Ground Water Management Plan. The State Engineer and/or his staff attended most of the meetings and workshops to advise the GWMPC and Water District staff of the tools that are available under existing Nevada water law. DWR staff remains involved in the effort to assist with drafting a Ground Water Management Plan for the community of Pahrump and the larger Hydrographic Basin 162. This effort by

4 | Page the Ground Water Management Plan Committee has been both controversial and emotional as the subject matter has implications which impact the full spectrum of water use including agriculture, industrial, commercial, municipal, domestic and all other uses. After meeting for the past 21 months together with input and information from the public, Division of Water Resources, Nye County Commissioners and the Water District Governing Board; the Ground Water Management Plan Committee compiled more than 180 ideas to balance available water with future growth potential for the community.

After much consideration, discussion and debate, the committee has identified the following items which form the foundation for a GWMP. The priority items in no particular order are:

• Aggressive water education • Adopt a water conservation plan • Water importation • Require meters on new domestic wells • Limit new Domestic wells to 0.5 AFA • Educate domestic well owners regarding the option to supplement their water usage with permitted water rights • Construct rapid infiltration basins and/or recharge basins • Aquifer Storage and Recovery • Allow utilities to put in backbone infrastructure with PUC approval to reach more lots • Create incentives to voluntarily connect to public water systems • Conservation Credit Program for water rights • Investigate existing and future development agreements and implement changes with the goal to require water mitigation. • Growth Control

Water District staff was instructed by the WDGB to provide support for the GWMPC and have attended all of the meetings and workshops, provided background information, and have been tasked with drafting a GWMP for WDGB, BOCC and DWR consideration. This report includes the following Chapters and is based on the GWMPC recommendations:

• CHAPTER 1 - Introduction • CHAPTER 2 - Basic Pahrump Basin Water Resources Facts and Figures • CHAPTER 3 - History and Reference to Statue(s) • CHAPTER 4 - Pahrump Basin Hydrology Considerations • CHAPTER 5 - Recommendations from the Groundwater Management Plan Advisory Committee

AF - Acre Feet AFA - Acre Feet Annually AR - Artificial Recharge ASR - Aquifer Storage and Recovery BLM - Bureau of Land Management BOCC - Nye County Board of Commissioners BOR - Bureau of Reclamation DRI - Desert Research Institute DUI - Desert Utilities Inc. DWR - State of Nevada Division of Water Resources GPCD - Gallons Per Capita Day (what each person uses in gallons per day) 5 | Page

GWMP - Groundwater Management Plan GWMPC - Groundwater Management Plan Committee NCC - Nye County Code NCWD - Nye County Water District PUCI - Pahrump Utility Company Inc. PUCN - Public Utilities Commission of Nevada PY - Perineal Yield RIB - Rapid Infiltration Basin UICN - Utilities Inc. of Central Nevada USGS - Unites States Geological Survey WSAIR - Water Supply Appraisal Investigation Report WDGB - Nye County Water District Governing Board WLMP - Water Level Measurement Program

CHAPTER 2 - BASIC PAHRUMP BASIN WATER RESOURCES FACTS AND FIGURES

(A) – Perennial Yield vs Permitted Water Rights

Basin 162 Perennial Yield is 20,000 AF - this represents DWR’s assessment of the total available water resources on an annual basis in Basin 162 and includes portions of Nye and Clark Counties.

Table 1a - June 2015, Underground Water Rights currently permitted by manner of use [Ref. DWR website]:

Commercial 1195 AF Construction 287 AF Domestic 7291 AF (Relinquished in support of parcel map applications and subdivisions) Industrial 162 AF Irrigation (DLE) 700 AF (Desert Land Entry) Irrigation 11,754 AF Mining and Milling 10 AF Municipal 30,671 AF Quasi-Municipal 7850 AF Recreation 491 AF Stockwater 5 AF Total Permitted 60,416 AF

Table 1b – Basin 162 Pumpage by Manner of Use, [Ref. *DWR Assessment of Groundwater Pumpage 2013]:

Commercial 498 AF Industrial and Construction 67 AF Domestic 5,502 AF (Includes Domestic well estimate) Irrigation 3,466 AF Mining and Milling 3 AF Municipal 4,106 AF Quasi-Municipal 443 AF Recreation and Wildlife 263 AF Total 2013 Pumpage 14,348 AF

*DWR Ver. 2013 Assessment of Groundwater Pumpage is the most recent data available as of Sept. 2015.

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(B) – Over Dedication of Water Rights

For more than 15 years the Division of Water Resources and Nye County have required over dedication of water rights in support of subdivision of lands in the community of Pahrump. Today the ratio required for dedication is approximately 3-4 AFA for each 1 AFA to be placed to use. The over dedicated water rights are primarily held by utility companies doing business in the community, who have supported the over dedication requirements. These water rights are permanently dedicated to each parcel and it is unlikely that all the over dedicated amounts will ever be utilized in any manner. In addition, parcel map applications require relinquishment of water rights for each new parcel created. The exact number in acre feet of over dedication + relinquishment v/s actual use (to date) has not been quantified but these water rights are counted in the over appropriation of the basin. The development community has been participating to bring water used for development in balance with the available water resources by either over dedication of water rights, reuse of effluent, or outright relinquishment in support of development and through conservation and mitigation within the developments. More information is needed to quantify what the total combination of over dedication + outright relinquishment means to the larger water budget, but it will be a significant number.

There is nothing in the statute that expressly prohibits the utility from moving excess dedicated water to other uses, including additional development. DWR maintains that they will not allow these excess dedications to be moved and/or used for anything other than the original purpose of the dedication. Permanent relinquishment of the subject over dedications would put the issue to bed, but it remains to be seen exactly how this will play out between the utilities, the Public Utility Commission of Nevada and the DWR. Staff suspects that given the attention the Pahrump basin is receiving from the DWR, and moreover the entire State, it is highly unlikely the over dedicated water rights will ever be pumped and will continue to lie in limbo.

The WDGB heard and passed a resolution on July 27, 2015 to require relinquishment of “2 AF for each 1 AF to be placed to use” for all commercial and industrial development within the Community of Pahrump. A copy of the resolution is attached in Appendix A.

In addition to permitted water rights, the community of Pahrump has more than 11,000 existing domestic wells and currently has sufficient vacant parcels to drill an additional 8,500 domestic wells. It is generally accepted that on the average the domestic well owners in the Pahrump community are not pumping their full 2 AFA to which they are entitled under Nevada water law. The DWR acknowledges this and is currently using an estimate of 0.5 AFA per domestic well for water budgeting purposes.

Additionally, the Nye County Water District is sponsoring a voluntary domestic well metering program. Of the 13 wells in the program 7 have multiple year’s data collected to date. The average use from these 7 wells indicates that the domestic well owners (to their credit) are using approximately 0.52 AFA. “Average” use takes in to consideration that some domestic wells are not used at all (zero use) while others use the full 2 AF (or more on some limited basis). The Water District hopes to add data from the remaining 6 wells within the next 12 months. Unfortunately 13 wells (of 11,000) do not provide an adequate sample size and therefore the metering program does not support a defendable conclusion at this time. More effort on the part of the Water District, DWR and the community of Pahrump is required to install a sufficient number of meters and collect 7 | Page more data to quantify actual average domestic use for the community. Based upon the previous statements, and for the potential groundwater withdrawal calculation presented in Table 1, the domestic well component is calculated at [11,000 + 8,500] X 0.5 AFA = 9,750 AFA.

(D) – Potential Groundwater Withdrawal Overdraft

Potential groundwater withdrawal within the area of the Pahrump community includes two components: 1.) Permitted water rights, and 2.) Domestic wells. Table 2 places the potential groundwater withdrawals at 70,166 AFA.

Table 2 provides a breakdown of:

• The Perennial Yield of Basin 162. • Existing water rights permits as of June, 2015 (Reference: DWR Hydrographic Area Summary). • Estimated existing and future domestic wells with estimated usage at 0.5 AFA per domestic well. • A total potential groundwater withdrawal which is calculated using existing water rights + domestic well pumpage. • The estimated over allocation or potential shortfall of 50,166 AF.

Table 2: Perennial yield of 20,000 AF versus potential groundwater withdrawal

PAHRUMP HYDROGRAPHIC BASIN

EXISTING PERMITTED WATER RIGHTS 60,416 AF

EXISTING + FUTURE DOMESTIC WELLS 9,750 AF *POTENTIAL GROUNDWATER WITHDRAWAL 70,166 AF PERENNIAL YIELD 20,000 AF OVER ALLOCATION 50,166 AF

*Potential groundwater withdrawals are the sum of: 1.) Existing water rights 60,416 AF. (Ref. DWR website Jun. 2015) 2.) An estimate of existing and future domestic wells at 0.5 AF per domestic well (estimated at 11,000 existing + 8,500 future)

(E) - Potential Offset to the Over Allocation Figure

Pahrump presently has direct effluent reuse used for irrigation, has RIBs in use for effluent recharge (as opposed to other types of effluent management) and has RIBs in use for flood control, all of which provide usable water resources and/or a recharge component. In addition to reuse and recharge factors, over dedication of water rights further offsets the over allocation figure. The existing and potential benefits are currently not quantified but will have significant impacts to over allocation.

Utilities providing both water and sewer service collect some 40% of the overall water delivered to the home as return to the wastewater treatment facility. If the utility utilizes a RIB (as opposed to other types of effluent management), this provides a significant recharge component to the water resource and is not included in the

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20,000 AF PY. In addition one utility in the community has utilized effluent for irrigation. It is predicted that future effluent reuse will become more attractive as water rights become increasingly scarce.

Rapid Infiltration Basins for flood control have the dual benefit of controlling flood water and recharging the basin water resource. It is predicted that Nye County, combined with efforts underway by the Public Works Department, will continue to encourage RIBs for development projects as part of flood control plans and water use mitigation and will ultimately construct RIBs for overall community flood control projects.

As stated previously in this report; for more than 15 years the Division of Water Resources and Nye County have required over dedication of water rights in support of development in the community of Pahrump. Today the ratio required for dedication is approximately 3-4 AFA for each 1 AFA to be placed to use. The exact number in acre feet of over dedication + relinquishment v/s actual use has not been quantified (existing or potential) but these water rights are counted in the over allocation of the basin in Table 1. Providing an accounting for both [existing and the potential for] reuse, recharge and over dedication is an important component of the GWMP effort.

Table 3, proposes a future reuse/recharge credit of TBD AF (to be determined) which will significantly offset the over allocation figure of 50,166 AF. Table 3 also proposes that over dedication of water rights would further offset the over allocation figure.

Table 3: Adjustment of over allocation by crediting reuse, recharge and over dedication of water rights

PAHRUMP HYDROGRAPHIC BASIN PERENNIAL YIELD 20,000 AF OVER ALLOCATION 50,166 AF REUSE CREDIT POTENTIAL TBD AF

RECHARGE CREDIT POTENTIAL TBD AF OVER DEDICATION POTENTIAL - SUBDIVISIONS TBD AF OVER DEDICATION POTENTIAL - DOMESTIC WELLS TBD AF *ADJUSTED OVER ALLOCATION TBD AF *Adjusted over allocation: 1.) Credits reuse and recharge water as usable water. 2.) Significantly reduces the over allocation total by accounting for over dedicated water rights (existing + future should be included). 3.) 1 and 2 combined would be subtracted from the 50,166 over allocation figure.

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The GWMPC recommends: Reuse, recharge and over dedication should be captured, quantified and presented in report form to account for existing + future potential reduction to the over allocation total as indicated in Tables 2 and 3. This effort should include NCWD and DWR staff and will require review of information on record at the offices of Nye County, NCWD and DWR.

(F) – Projected Total Usage at Build-out

The current population estimate for the community of Pahrump is 38,929 (Nye County Planning, 1st quarter 2015). Based upon available deeded lands, previous versions of the Pahrump Master Plan have predicted it is possible to create sufficient parcels to support a population of 495,000. However, the 2014 Pahrump Master Plan Update has scenarios which, if implemented, could reduce this full build-out population to a range of 103,000 to 376,000 (Review of the 2014 Pahrump Master Plan to understand the scenarios presented and calculated therein is recommended). A fractional portion of the higher population projections could outstrip the groundwater resources that lie beneath the community. Information on the Master Plan can be obtained from the Nye County Planning Department, Pahrump Office.

The Nye County Water District operates a Water Level Measurement Program (WLMP) in the Pahrump Basin. Water level data from the Pahrump WLMP is provided in Appendix B of this report. This water level monitoring effort indicates that water levels along portions of the alluvial fan are rising while water levels in portions of the valley floor are declining. In 2013 overall groundwater pumpage in the Pahrump Basin 162 was approximately 14,348 AFA which includes both permitted water rights and estimated use from > 11,000 domestic wells. Perennial Yield and groundwater pumpage is established and tracked by the DWR and can be found on the DWR website at www.water.nv.gov.

Although the PY for the overall basin is 20,000 AFA and 2013 pumping was published at 14,348 AFA, groundwater levels within much of the area comprising the valley floor - where 85% of the domestic wells are located - continue to decline.

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Figure 1: Density of domestic wells in Pahrump per square mile shown in blue (i.e. 11)

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CHAPTER 3 - HISTORY AND REFERENCE TO STATUTE(S)

(A) – Historical Reports and State Engineer Orders

Included in Appendix C is a summary and narrative summary of a report titled “WATER SUPPLY FOR THE FUTURE OF SOUTHERN NEVADA”. The report was prepared for the DWR State Engineer more than 40 years ago and provides insight to the development of southern Nevada and addresses possible solutions to looming water shortages. It is an interesting report and touches upon several items that are identical to those facing the community of Pahrump today.

Included on Page 30 of this GWMP is reference to USGS reports on Pahrump Basin geology and hydrology.

Included in Appendix D is Order 1252 from the State Engineer regarding the Pahrump Basin. This order is dated April 28, 2015 and further restricts water appropriations in the Pahrump Hydrographic Basin, removes the fan/floor designation and in part states: “It is ordered that, with the following exceptions, any application to appropriate groundwater pursuant to NRS Chapters 533 and 534 within the designated Pahrump Valley Hydrographic Basin will be denied.

EXCEPTIONS:

1. Those applications for Environmental permits filed pursuant to NRS 533.437 to 533.4377, inclusive. 2. Those applications for temporary appropriation of groundwater for stockwater purposes during drought declarations filed pursuant to NRS 533.504. 3. Those applications for temporary appropriation of groundwater for establishing fire-resistant vegetative cover filed pursuant to NRS 533.436. 4. Those applications filed to increase diversion rate only, with no corresponding increase in duty of water.

Nevada water law is based on priority doctrine which simply means “first in time, first in right” -or further- those holding the oldest water rights are the last to be curtailed. Portions of this report attempt to shed light on various complex and confusing issues centered upon senior water rights versus junior water rights, which includes regulation of the domestic well. Careful review of the Nevada Revised Statutes, particularly NRS 278, 532, 533, 534, 540 and 543 is recommended. Understanding the statutes and administration of the statutes by DWR [with regard to priority doctrine as it relates to a GWMP for the community of Pahrump] is the only way the reader will fully understand GWMP issues and implications.

Attached in Appendix R is a document titled Nevada Water Law 101. This document provides information on history, the application process, beneficial use and other items regarding water law as administered by the State Engineer. This document is also available on the DWR website at: dcnr.nv.gov/documents/documents/nevada-water-law-101.

An excerpt from this document reads: “Nevada water law has the flexibility to accommodate new and growing uses of water in Nevada while protecting those who have used the water in the past. All water within the boundaries of the state, whether above or beneath the surface of the ground, belongs to the public and is subject to appropriation for beneficial uses.

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Nevada water law is based on two basic principles: prior appropriation and beneficial use. Prior appropriation – also known as “first in time, first in right” – allows for the orderly use of the state’s water resources by granting priority to senior water rights in times of shortage. This concept ensures senior water users are protected, even as new uses for water are allocated. A water right permit may only be granted for beneficial uses as provided in Chapters 533 and 534 of the Nevada Revised Statutes.

Examples of beneficial uses include irrigation, mining, stock watering, recreation, commercial, industrial, and municipal uses. Beneficial use also includes the underlying principle of the appropriative rights system of water allocation, known as “use it or lose it.” In the West, where water resources are scarce, water users must demonstrate an actual beneficial use of water. They cannot speculate in water rights or hold on to water rights they do not actually intend to place to a beneficial use in a timely manner. If they stop using the water, they will lose the water right.”

(B) - Statutes and Regulations Governing the Division of Water Resources

NRS 532 - State Engineer NRS 533 - Adjudication of Vested Water Rights; Appropriation of Public Waters NRS 534 - Underground water and Wells NRS 534A - Geothermal Resources NRS 535 - Dams and Other Obstructions NRS 536 - Ditches, Canals, Flumes and Other Conduits NRS 537 - Navigable Waters NRS 538 - Interstate Waters, Compacts and Commissions NRS 540 - Planning and Development of Water Resources NRS 543 - Control of Floods NRS 278 - Planning and Zoning NAC 532 - Fines and Penalties NAC 533 - Practice and Procedure in Protest Hearings Before the State Engineer NAC 534 - Regulations for Water Well and Related Drilling

Detailed information on the above can be accessed on line at: www.water.nv.gov or the Nevada Law Library at: www.leg.state.nv.us/Law1.cfm.

NCC 17.04.740(F) Development standards: Establish design requirements that reduce water consumption in the portion of the Pahrump groundwater basin encompassed by the Pahrump Regional Planning District.

NCC 16.28.170(H)1.a Water Rights: For Parcel Maps Located Outside of a Water Service District: Because of concerns over water in the Pahrump Regional Planning District, certificated water rights in the amount of three (3) acre feet for each additional parcel created, regardless of the type of zoning or the size of the parcels created, excluding the existing parcel shall be relinquished to the Nevada State Engineer's Office, Division of Water Resources. The 1 acre-foot is a surcharge, and only 2 acre-feet of the 3 acre-feet relinquished

13 | Page may be used for a domestic well or "small commercial use"(equal to or less than 2 acre-feet) if permitted by the State Engineer. For example, a 20 acre parcel divided into 4 parcels would require nine (9) acre-feet of water rights, which is calculated as follows: 3 additional parcels x 3 acre-feet per additional parcel = total of nine (9) acre-feet of water rights. The costs associated with water rights transfers shall be borne by the applicant. Because of the costs involved with water rights transfers, this requirement shall be made a condition of approval of a parcel map. (Ord. 288, 2004)

CHAPTER 4 – PAHRUMP BASIN HYDROLOGY CONSIDERATIONS

(A) - Water Level Measurement Program The Nye County Nuclear Waste Repository Project Office began a water level measurement program in 1999, to collect water level information from private and public wells in the Pahrump and Amargosa Valleys. The WLMP continues today, operating as a program of the NCWD. In Basin 162, 73 wells are measured on a bimonthly basis. Figure 2 shows the distribution of wells monitored as part of the WLMP. The data collected under the WLMP are useful for evaluating changes in water level over time and observing trends in water levels. Hydrographs for wells monitored in Basin 162 as part of the WLMP are shown in Appendix D, and a 10- year water level change map is shown on the following page in Figure 3. As shown in Figure 3, water levels are generally declining in the basin-fill aquifer, while water levels are increasing in the alluvial fan aquifer.

The GWMPC recommends: The WLMP provides crucial information with regard to overall basin health and the Committee strongly recommends this program continues to be funded.

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Figure 2: Distribution of wells monitored as part of the WLMP in Basin 162.

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Figure 3: 10 year water level change map for Basin 162.

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(B) - Redistribution of Production Wells The concept of redistribution of production wells is to reduce groundwater withdrawals in areas with a high density of wells, or in areas where water levels are declining. Ideally, water supply wells would be placed in areas where water levels are increasing and the water distributed to users in the areas where levels are declining. Pumping in the areas of decline would be reduced, allowing water levels to recover. In order for this to work, several key changes would need to take place. Note that none of these changes are expected to be easy, or happen quickly – the time scale for development of such a system is on the order of tens of years, and may require the involvement of DWR, PUCN and local water utilities. Areas that are candidates for pumping locations include a.) The alluvial fan (water levels increasing) and b.) near the state line on the south end of the community of Pahrump.

• Interconnection of systems – Existing water supply systems would likely need to be interconnected to convey water from the pump location to end users. This item would also be required to convey water if imported from outside the Basin, as discussed in the Importation section of this document. The scope and scale of this effort is largely undefined, but several interconnection projects have either been completed or are underway. Information regarding existing and ongoing interconnection projects is provided in Appendix E. • Consolidation of utilities – Another possibility would be to combine the three private utilities into one company who would then interconnect the systems and convey water to its customers. As with the interconnection of systems, this would not be done in the short term and would require input from DWR, PUCN and others. • Aquifer Storage and Recovery (ASR) or artificial recharge – Water could be injected into the aquifer to increase water levels and stored there permanently (artificial recharge) or withdrawn seasonally for use (aquifer storage and recovery). This concept, as well as potential candidate locations, is discussed in more detail in the WSAIR. Information regarding a potential ASR project is included in Appendix F. • Wholesale water purveyors (NCWD as SNWA) – The NCWD has the legal power to act as a wholesale purveyor of water. In this case, the NCWD would be responsible for identifying areas where water could be produced but has not been developed (i.e. south of the PRPD), drilling wells, working with utilities to interconnect systems for distribution, and selling the water to the utilities. Advantages of such a scenario would be the ability for the NCWD to target production areas based on the data collected as part of the WLMP, to tap into water that is not currently being captured in Basin 162, and the ability to generate revenue to increase the scope of the monitoring program (i.e., monitoring and assessing the efficiency of and impacts to the groundwater flow system from production wells). • Another alternative is for existing utility wells to be used to supply water for ASR, AR, etc. (i.e., utilities wholesaling water to the NCWD). This requires investigation of potential effects of increased pumping at utility wells currently being pumped or not pumped on downgradient wells. • Significant technical challenges are anticipated with any of the interconnection/consolidation scenarios described above. However, the first step in any such effort will be thorough evaluation of the physical properties of each system (e.g., pipe sizes, distribution pressures, spatial extent). Based on the results of these evaluations, engineering design and analysis will then be conducted to plan the actual interconnection/consolidation.

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• It must be noted that for any of the above scenarios to take place, political fortitude on behalf of the NCWD and BOCC must exist and remain strong throughout the planning and establishment of such systems. Absent this will, these projects will not come to fruition. • DWR Order 1252 allows movement of water rights from the valley floor to the fan. Because water levels are rising on the fan, this Order may provide opportunity to ease pumpage on the valley floor (where water levels continue to decline) under redistribution of pumping scenarios presented in this section. This Order has no impact to the drilling or use of domestic wells, other than adding a tool to stabilize water levels.

(C) - Use of Groundwater Flow Models as Planning Tools Groundwater flow models, such as the model constructed by Glorieta Geoscience, Inc. (GGI), can be used to simulate the effects of pumping groundwater in a particular location on the wells around that location. This is potentially useful once drilling targets have been identified and water production/extraction rates are being considered. If the model shows that pumping in a certain location at a certain rate will have negative impacts on nearby wells or cause excessive drawdown, it may be necessary to seek alternative pumping locations.

A hydrologic and hydrostratigraphic assessment is being conducted by Leising Geoscience for the Nye County Water District (at the request of the GWMPC) with the intention of ultimately identifying areas in the Pahrump Groundwater Basin where conditions are most favorable for groundwater development. Once specific drilling target areas have been identified as part of this assessment, they can be checked against the GGI groundwater flow model to determine potential effects of groundwater pumping on nearby wells. Likewise, as wells are installed, information gained during drilling and pumping can be used to update the flow model.

The GWMPC recommends: Groundwater modeling should be funded and utilized as a planning tool in concert with the WLMP and other studies.

CHAPTER 5 - RECOMMENDATIONS FROM THE GROUND WATER MANAGEMENT PLAN ADVISORY COMMITTEE

(A) - Aggressive Water Education

In order to educate residents of Basin 162 about current water issues, promote a conservation ethic, and create community pride in responsible management of water resources, the GWMPC has included water education as one of their top priorities. Measurements of success and progress should include (for each conservation effort) quantification of reduction in water use (gpcd) and be publicized as widely as possible to ensure community awareness. Staff has identified several possible approaches to accomplishing this priority. These approaches are, in no particular order:

• Education in schools – Efforts on this front to date have included: 1.) NCWD staff demonstrating physical aquifer material properties and a physical aquifer model for several elementary school classes in Pahrump. In addition, the climate/water cycle is part of the general elementary school science curriculum. Along with these demonstrations we included a discussion about water resources in the Basin, potential overuse, and ideas for conservation measures the students themselves could affect (e.g., taking shorter showers, turning off the faucet while brushing teeth, etc.) 2.) UICN provides water

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education materials to all 1st and 2nd grade classes in Nye County. These materials, developed in coordination with Nevada Rural Water Association, consist of a monthly calendar and activity book. Additional items include “Be Water Smart” pencils, wristbands, erasers, and rulers. Further efforts to pursue this education could include reaching out to all of the elementary schools in the Basin, as well as the middle and high schools. In addition to the aquifer materials and model demonstrations (and associated conservation discussions), the NCWD has a surface runoff model that could be used to demonstrate the interaction between surface activities and the groundwater supply, as well as potential contaminant transport.

• Informational brochures – UICN currently publishes information related to drinking water supply and supply protection, water treatment and distribution, and conservation tips. This information could be placed at the Pahrump Chamber of Commerce (and/or other locations as determined by the GWMPC) in the form of brochures for distribution to the community.

• Articles for the newspaper(s) – During the time the GWMPC has been meeting, significant press has been given by both of the newspapers in Pahrump. Reporters generally attend the meetings and provide coverage through articles of the activities of both the GWMPC and the WDGB. One of the challenges with this coverage is that facts surrounding water issues are often lost in the course of discussion and consequently the information published in the articles is not entirely accurate. To help remedy this issue, staff recommends a series of press releases detailing the underlying water issues, the steps being taken to define the problems, and potential solutions.

• Radio spots – The local radio station (KNYE 95.1 FM) provides a no-cost forum for discussion of local issues, which is often used by local politicians, officials, and others to discuss issues relevant to the time. The format of this forum allows the speaker time to present a topic, answer questions posed by the host, and answer questions from callers. This forum could be used to present information on water issues to the radio audience using the same materials developed for release to newspapers. One advantage of this approach would be the opportunity to clarify through discussion any of the issues that are not necessarily intuitive. In addition, 97.7 FM airs water-related information.

• Local TV spots – Similar to the radio and newspaper formats, the local television stations could be used to communicate water-related issues to the public. The advantage of using this media outlet is that images can be shown to illustrate key points in the discussion. Community Viewpoint is a show on Channel 41 dedicated to discussion of issues affecting the community, and as such, would serve as an ideal forum for the discussion of water issues. This show is generally hosted in a discussion format, with the guest presenting a topic and the host asking questions, providing other relevant information, etc.

• Marketing – Consideration should be given to contracting with a marketing firm to champion portions of the overall public outreach and education effort.

• Bottles of water with 10 Commandments of water use – Water bottles can be ordered from companies who also create custom labels and apply them to the bottles for a nominal cost. For example, www.personalizedbottlesofwater.com sells 16.9-ounce water bottles with 2x8-inch full color labels for $0.60 each (if ordering 25 cases). Ordering larger quantities results in a lower cost per bottle. These could advertise the “10 Commandments” of responsible water use to serve as reminders to people to

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conserve water. These water bottles could be distributed to community functions, to students during educational sessions, and more. Staff suggestions for the 10 Commandments include (there are many more tips available on the internet that could be substituted or incorporated):

1. Water outside vegetation only during cooler times of day. 2. Shut the faucet off while shaving/brushing teeth/etc. 3. Remind your children to take shorter showers. 4. Replace water-loving vegetation with low water-use plants. 5. Consider xeriscaping part of your yard. 6. Incorporate native vegetation into your landscaping. 7. Fix irrigation leaks promptly. 8. Install low-flow water fixtures in your home. 9. Keep a bottle of drinking water in your refrigerator (don’t run the tap to cool water for drinking). 10. Place mulch around outdoor plants to reduce evaporation.

The GWMPC recommends: In order to inform residents of Basin 162 about current water issues, to promote conservation, and raise the general awareness level; water education must be a top priority. The Committee acknowledges the attention that local media has given to the subject of water issues and strongly recommends that; a.) The NCWD, Nye County the DWR view education and outreach as a priority item and b.) Consideration of the options as outlined previously in this section.

(B) – Adopt a Water Conservation Plan

Purpose • Contribute to achieving a balance of water supply and demand in the Pahrump Valley • Recommend fair usage restraints on all water users o Agriculture o Utility Customers o Domestic Wells o Commercial o Government and School District facilities

Goals • Avoid crisis-level aquifer depletion in the long term • Balance between quality of life and conservation • Reach an overall gallon per day per capita (gpcd) of 198 gpcd o Includes Commercial, Industrial, Residential, Municipal, etc. o Per the December 2014 Pahrump Master Plan Update • Recommend that this Conservation Plan immediately applies to all new construction • Recommend staged implementation for current homes and businesses but encourage immediate conservation via outreach programs and incentives

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Recommended Conservation Plan Implementation Approach: • Revise NCC development codes 17.04 Articles IV (Planned Unit Development) and Article VI (Development Standards) as indicated below for more water conscious landscaping design requirements and water conservation regulations for new construction. • Revise the three existing Utility Water Conservation Plans (UICN, PUCI, and DUI) as indicated below for consistency in their conservation mechanisms for utility-based users • Combine and extend the conservation elements of the revised Nye County Code and Utilities Water Conservation Plan’s into a basin-wide Conservation Guideline which would provide an educational document for all properties including those based on domestic wells.

New Construction Landscaping • All landscapes must be: o Drought Tolerant o Desert Friendly o Water Conscious • Recommended plants, trees, and shrubs for landscaping are included in Appendix G.

New Construction Turf Restrictions

• Grass turf consumes 41 gallons of water per square foot per year (*or 5.5 AFA) in our high-desert environment. (Ref: National Institutes for Water Resources and comments received from Nevada DWR) • 1500 square feet is the maximum turf allowed for any single family residence • The yearly water usage of that 1,500 sq. ft. of turf is equivalent to 169 gallons per day (**or 0.19 AFA) • Turf in the front yard area is prohibited (can apply for a waiver) • Turf shall be at least 3 feet from all buildings, structures and walls • Turf shall be at least 15 feet from the pavement of all streets • Planting cool season grass, such as Rye and Fescue, from seed is prohibited from May through August. Laying sod is permitted. • The Water District will work with the three present golf course facilities (Mountain Falls, Lakeview Executive, and Desert Greens) to review their designs and water usage in order to establish rational conservation regulations for existing golf courses. • All new Golf Courses should limit turf to 3-5 acres of turf per hole and watered with effluent reuse water to the extent feasible.

*Acre Feet Annually (AFA) for turf is calculated as: 41 gal./sq. ft./year [divided by] 7.48 gal/cu. ft. = 5.5 AFA ** Acre Feet Annually for 1,500 sq ft of turf is calculated as: 41 gal/sq. ft./year [multiplied by] 1,500 sq ft [divided by] 43,560 sq. ft./acre [divided by] 7.48 gal./cu. ft. = 0.19 AFA

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New Water Features, Ponds, and Artificial Lakes • Ponds, and lakes evaporate water at a rate of 49 gallons per square foot per year or 6 AFA (Ref: National Institutes for Water Resources and comments received from Nevada DWR) • Decorative water features and ponds are limited to less than 50 square feet surface area • Swimming pools and spas are not size-restricted; appropriate use of pool & spa covers is encouraged • Bodies of water for recreational use larger than 250 sq ft require a Conditional Use Permit regardless of the water source. • All ponds, water features, and newly constructed bodies of water shall be lined.

Water Application for New Construction (and encourage for existing) • Automatic irrigation systems are required for all common area, residential, agricultural and commercial planting areas of new construction. • Overhead spray shall be minimized and restricted to turf and flower beds. o All other areas of landscape must use low volume drip lines. • If spray heads are required next to roads or paths they shall be low angle (10%) nozzles. o Large radius spray heads are prohibited along roads and paths. • All spray heads are prohibited from spraying water directly onto any roads, paths, other non-turf surface or another parcel. • All spray heads are prohibited from causing runoff onto any roads, paths, other non-turf surface or onto another parcel. • Encourage no watering during high winds. • Wasting water is unlawful per NRS 534.0165, 534.020(2), 534.070 and NAC 704.567

Watering Schedule for Landscaping (This applies to everyone in the community) • All common area, residential units, and commercial areas shall comply with watering schedules issued by Nye County Water District (NCWD) which sets forth the days, time of day, and duration of time allowed for outdoor watering. o From November 1 through February watering is limited to one day a week. o From September 1 through October and from March 1 through April, watering is limited to three days a week. o From May 1 through August watering is allowed 7 days of the week (but see recommendation below for summer watering).

Additional Watering Restrictions: • From May 1 until Oct. 1, sprinkler and drip system watering is prohibited from 11 a.m. to 7 p.m. Watering with a handheld hose and supervised testing of your irrigation system are allowed anytime. Watering new or reseeded landscapes daily for up to 30 days is allowed once per calendar year. • In the summer, watering restrictions allow landscape watering any day of the week through August. We recommend watering four days per week and increasing the schedule only if your landscape needs more water.

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Low flow Fixtures • All fixtures must be Low Flow Fixtures as required by Nye County Building Code at the time of installation. (Both residential and commercial.) • Offer Low Flow toilet rebate.

Conservation Incentives from the Water District • Free Leak Detection Kits for toilets • Pay to Remove (This becomes a deed restriction): o Turf at $0.50 per sq ft (Max $450 per year per parcel) o Salt cedars at $75 per mature tree (Max $450 per year per parcel) o Total yearly incentives are limited to the NCWD budgeted amount.

Prohibited Plants for New Landscaping • Salt Cedars o Mature salt cedar trees consume as much as 200 gallons per day per tree o Salt Cedars of any size shall be removed from a property prior to any new development.

Notes: 1.) Salt Cedar is an invasive species. See report titled Fighting Invasive Weeds a Cooperative Extension publication. Page 71 of the report outlines eradication of Salt Cedar. This report can be found at: https://www.unce.unr.edu/publications/files/ho/2005/eb0502.pdf. Additional assistance is available at the University of Nevada Cooperative Extension located at 1651 E. Calvada Blvd, Pahrump, NV 89048, Phone (775) 727-5532. 2.) NRS 555.202 Legislative declaration. The Legislature declares that it is primarily the responsibility of each owner or occupier of land in this State to control weeds on his or her own land, but finds that in certain areas this responsibility can best be discharged through control by organized districts. 3.) Regarding organized districts; Tri County Weed Control provides both public and private sector noxious weed control and serves Nye, Lincoln and White Pine Counties. Information regarding the organization and the services they provide can be found at: http://www.tri-countyweedcontrol.com or by calling 775-289-6341.

Enforcement • Enforcement should be practical. • Before a Certificate of Occupancy is issued, evidence that the Conservation Plan was followed should be included in the building inspection. • NCWD or Nye County Code Enforcement shall enforce all conservation and watering requirements. • Require new developments to include these water conservation standards in its Design Guidelines and CC&R’s, and require the Board of Directors of the Home Owner Association or commercial association to also be responsible for enforcing all conservation and watering requirements.

Note: Enforcement will be a combination of County Code and regulations as enforced by DWR. To report a violation, the DWR forms page can be found at water.nv.gov/forms, the form name is Request to Investigate Alleged Violation.

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Potential Impact of Conservation Savings • The latest available Division of Water Resources “Pumpage Inventory Report”, year 2013, shows a total water usage of 14,348 AFA for all types of uses – residential, commercial, industrial, municipal, recreation and agriculture irrigation. • With the agricultural irrigation use of 3,466 AFA subtracted out, the remaining usage of 10,882 AFA divided by today’s Pahrump population of 38,929 people (Nye County Planning) shows the per-capita daily use today at that level of total pumping would be 250 gpcd. • If conservation efforts were to reduce that gpcd figure by 21% to the 198 gpcd goal of the Pahrump Master Plan Update, about 11,000 additional people could be supported by that same amount of pumped water.

The GWMPC recommends: The conservation plan as outlined in this section should be implemented starting with required revisions to Nye County Code.

The GWMPC has identified water importation to the community of Pahrump as a priority recommendation. At the Dec. 3, 2012 meeting of the Nye County Water District Governing Board, staff was instructed to provide preliminary cost estimates for possible water importation to the Pahrump Basin. A report was completed and presented to the WDGB in February 2013. This report presents some of the challenges to identify sufficient water resources in a series of basins north of Pahrump and provides a basic cost outline. The preliminary cost estimates included in the report assume importation of 5000 AFA to the community that would serve some 30,000 people (residential only at 150 gpcd). Because the report was completed in Feb. 2013, it has been revised as follows: Update of the PY from 12,000 AF to 20,000 AF, update of the current Pahrump population estimate and update of the pumpage inventory for the Pahrump Basin. Cost updates are not included in the June 2015 revision. The Water Importation Report is included in Appendix H.

The importation report presents a scenario where water is delivered to the community of Pahrump from some 70 miles distant at a cost approaching $173,000,000. As stated previously, 20,000 AF Perineal Yield may support a population of 80,000. This begs the question; “What then, is the trigger to actively pursue water importation to Pahrump?”. The short answer lies with the effort by the Southern Nevada Water Authority (SNWA) to import water to Las Vegas when, 25 years ago, they filed water rights applications in Lincoln, White Pine and Nye Counties. To date, the battle to secure the water rights and Rights of Way for the pipeline rages on. The GWMPC does not compare the scope of the Pahrump importation scenario to that of the SNWA importation project, but certainly compares the subsequent legal battle to place the water to use as an example of the challenges.

The GWMPC recommends: If the community of Pahrump wants to grow to a population exceeding *80,000 now is the time to begin actively pursuing importation beginning with a feasibility study of actual availability of potential source water. Any Interbasin transfer of water will take years to sort out, time and effort to secure funding, permitting requirements will become more restrictive and water rights will become increasingly expensive to secure. In short, importation may be possible but will take the political will to implement and is a lengthy and complex journey. The Importation Report is included in Appendix H.

*A population tip-over point of 80,000 does not fully consider the full potential of RIBS/recharge, effluent reuse and over dedication of water rights in support of development. This population figure v/s available water 24 | Page resources may exceed 100,000 should the projects and policies be implemented in a thorough manner as outlined in this GWMP.

(D) - Require Meters on New Domestic Wells and Limit New Domestic Well Usage to 0.5 AFA

The community of Pahrump has more than 11,000 existing domestic wells and has sufficient undeveloped parcels to drill an additional 8,500 domestic wells. As such, the domestic well component of the Pahrump basin water budget has the potential to consume 39,000 AFA, if all well owners were to pump the full 2 AF as entitled. However, using the estimate for an average use of 0.5 AF, the domestic well component is 9,750 AF (see Table 1 in this report) or nearly 50% of the 20,000 AF water resource.

Much of the debate surrounding the domestic well component in the Pahrump basin has been centered upon the fact that domestic wells have a priority date. The priority date of a domestic well is the date that the well is completed with the exception of wells drilled on those parcels where water rights in support of a parcel map application (through the County Planning process) were relinquished, which retain the priority date of the relinquished water right.

In Part: NRS 534.080; dates of priority.

4. The date of priority for the use of underground water from a well for domestic purposes where the draught does not exceed 2 acre-feet per year is the date of completion of the well as: (a) Recorded by the well driller on the log the well driller files with the State Engineer pursuant to NRS 534.170; or (b) Demonstrated through any other documentation or evidence specified by the State Engineer.

What this means to domestic well owners is that should the DWR regulate solely by priority, domestic wells in Basin 162 would in most cases be a junior right to the senior water rights issued in the basin (dating back some 65 plus years) and therefore are subject to curtailment “prior” to most of the water rights issued in Basin 162.

Limiting new domestic wells to 0.5 AF (8500 future domestic wells) would reduce the potential demand from 17,000 AF to 4,250 AF. Requiring meters on new domestic wells is recommended for tracking and reporting usage. To date, the DWR has not required metering of domestic wells, therefore has no way to quantify actual usage, or excess usage, other than observation of items such as irrigation of pasture, ponds and other high water use features. The GWMPC does not view propagation of domestic wells at 2 AF each as reasonable or responsible development.

Regarding the definition of a “new” domestic well: Existing domestic wells are not included and in addition, existing domestic wells that require any type of rehab, refurbishment or replacement are recommended to be exempt from being considered “New”.

The GWMPC recommends: 1.) Limiting new domestic wells to 0.5 AFA and 2.) That meters are installed on new domestic wells and annual usage be reported to DWR.

(E) - Educate New Domestic Well Owners on Supplemental Water Rights for Usage > 0.5 AFA

Should the DWR limit withdrawals from future domestic wells, owners of domestic wells may acquire water rights to supplement demand (which provides the means for future domestic well owners to pump in excess of 0.5 AFA). There is currently nothing in the Statute(s) prohibiting this. The process to acquire water rights and 25 | Page file change applications can be found on the DWR website at www.water.nv.gov and Change Applications can be found on the DWR website at http://water.nv.gov/forms.

The GWMPC recommends: Should Nye County and/or DWR follow the recommendation to limit new domestic wells to 0.5 AFA; every effort should be made by the Water District and Nye County to educate new domestic well owners regarding the option to supplement their water usage with permitted water rights. It is also recommended that the Water District staff compile a list of water rights brokers and water rights professionals doing business in the Pahrump basin to assist those interested in acquiring water rights. Part of this education/outreach effort should include information regarding a domestic well priority date, Nevada water law, senior water rights v/s junior water rights (priority doctrine), regulation by priority, curtailment and other items.

(F) - Construct Rapid Infiltration Basins

Rapid Infiltration Basins (RIBs) have a potential dual benefit for both flood control and infiltration to the aquifer. RIBS will require a substantial amount of engineering, staff time/expense to secure the required rights of way and/or lands and budget impacts on this item could be substantial.

The GWMPC recommends: a.) Investigation into RIB recharge potential in cooperation with Nye County Public Works and utilizing the Pahrump flood control plan, b.) Investigation and qualification into successful projects such as the raceway flood control detention basin and RIB and c.) reuse, recharge and over dedication should be captured, quantified and presented in report form to account for existing + future potential reduction to the over allocation total as indicated in Table 3. This effort should include NCWD and DWR staff and utilize information on record at the offices of Nye County, NCWD and DWR.

(G) - Aquifer Storage and Recovery and Artificial Recharge

Aquifer Storage and Recovery (ASR) or artificial recharge is a project where water could be injected into the aquifer to increase water levels and stored there permanently (artificial recharge; AR) or withdrawn seasonally for use (aquifer storage and recovery). This concept, as well as potential candidate locations, is discussed in more detail in the WSAIR.

At the March 15, 2013 meeting of the Nye County Water District Governing Board staff was instructed to provide information regarding Aquifer Storage and Recovery (ASR) to be included in the Water Supply and Appraisal Investigation Report, which was funded by the Bureau of Reclamation. The preliminary examination of Aquifer Storage and Recovery was completed in April 2013, reviewed by the WDGB, BoR and was included in WSAIR.

The ASR report considers the challenge to identify water resources in areas of the basin where water levels are rising and the distribution of water through pipelines to injection well sites which target areas of the basin with the highest density of wells together with declining water levels. The preliminary cost estimates included the ASR report assumed ASR of 1000 gpm or 1613 AFA. The report also represents a basic outline of what an ASR project might consist of, some necessary steps, challenges, a possible project sequence and a basic estimate of associated costs. Construction and permitting costs in the report are dated, so the report offers a limited snapshot in time and was intended to provide information for discussion, revision and refinement. ASR may provide one piece of a larger workable solution to balance [demand -versus- recharge] in the Pahrump Hydrographic Basin and for the community of Pahrump.

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The ASR project report is included in Appendix F. Note that in addition to the use of injection wells for ASR, RIBs may be used for AR. However, the permitting requirements for injection wells are more stringent than those for RIBs.

The GWMPC recommends: Further investigation into the feasibility of ASR and AR. This effort is tied to redistribution of pumping, the need for additional utility infrastructure, interconnection of utilities and other items that would stabilize water levels within areas of the valley floor, where water levels continue to decline.

(H) - Allow utilities to put in backbone infrastructure

For the purposes of this discussion, backbone infrastructure includes: pipe, pumps, flow control systems, tanks, wells, hydrants, valves and other items required to convey water. Acquisition and installation of this infrastructure is the most expensive investment made by any water utility. The Public Utilities Commission of Nevada (“PUCN”) governs private utilities and promotes the State policy that growth must pay for itself which means that utilities generally cannot install infrastructure without a development agreement or request for service by potential customers.

Backbone infrastructure provides the means for the water utilities to serve previously unserved “dry” lots and lots with owners seeking to abandon existing domestic or commercial wells. This will help reduce the drilling and re-drilling/deepening of wells and, ultimately, help to stabilize water levels in the valley floor aquifer. Previous sections of the GWMP discuss water importation, construction of RIBs, detention basins, ASR, and AR as potential ways to bring additional water into the basin, or to recharge the aquifer where water level declines are occurring. In order to implement any of those strategies, backbone infrastructure is required.

Allowing utilities to expand their existing infrastructure (without being tied to specific development agreements or requests for service) could help the community prepare to implement the strategies discussed above. Prudent backbone infrastructure planning should provide benefits to current utility customers and GWMP strategies.

The Pahrump utility companies are all regulated by the PUCN. Regulatory mechanisms for utility resource planning exist within Nevada Administrative Code (“NAC”) which could be used to proffer backbone infrastructure projects before the PUCN to determine prudency of any given project (i.e., NAC 704.565– 704.5688, 704.600 and 704.605). Interested parties may intervene in these dockets before the PUCN (as governed by law) which provides a mechanism for the various entities involved (RPC, DWR, NCWD, etc.) to transparently show their cooperation for any given backbone infrastructure project. As “growth pays for itself” is a policy of the State, legal action is not required for backbone infrastructure to be found prudent before the PUCN. The GWMPC recommends: Initiation of discussions between the utilities, PUCN, NCWD, DWR, RPC and others as necessary regarding the development of prudent backbone infrastructure projects in support of future GWMP implementation strategies, including limiting the proliferation of new wells.

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(I) – Create Incentives to Voluntarily Connect to Public Water Systems

The three utilities will discuss possible incentives and who bears cost of such incentives with PUCN. This item has a funding component. In essence: At such time as water mains are installed in the street; the domestic well owner will weigh the cost of connection to the utility -versus- replacing an existing domestic well that has failed. Utilities providing a funding mechanism to offset the cost to a domestic well owner of plugging and abandoning the well and drilling a replacement provides a.) Monetary incentive for the domestic well owner to connect to the utility and b.) Reduction in the density of domestic wells in areas where water levels are consistently declining.

Information regarding the State’s domestic well credit program is attached in Appendix I.

The GWMPC recommends: 1.) The utilities investigate the possibility of creating a monetary incentive for the domestic well owner to connect to the utility (possibly including such items as payment for the cost of plugging the domestic well, waiving connection fees, or other incentives). 2.) That staff investigate other incentive options related to reduction of domestic well density through well abandonment and connection to utility systems. This item is also related to potential expansion of backbone infrastructure and must be coevaluated.

(J) - Conservation Credit Program

Water District staff at the direction of the GWMPC and WDGB was directed to pursue a conservation credit concept as outlined below in this section. Senate Bill 81 (SB 81), considered during the 2015 legislative session, included language that supported the concept. The bill was passed by the Senate Sub Committee on Governmental Affairs but did not materialize in the Assembly and therefore died at the end of the 2015 session. In addition the Nye BOCC heard an agenda item in May 2015 which proposed the BOCC support SB 81. During the BOCC meeting a petition was presented that represented 71% of the water rights holders in Basin 162, in favor of SB 81. The item died at the BOCC level for a lack of a second to a motion to support the bill.

The GWMPC, WDGB and the State Engineer see the following conservation credit concept as a useful tool to include in a GWMP for Basin 162. The conservation credit concept may (in some form) be included in the 2017 Legislative Session. For this reason the GWMPC retains this concept as a priority recommendation to be included in a GWMP for the Pahrump basin.

The following represents a defined concept of a Conservation Credit Program for the Pahrump basin:

1.) To acquire a Conservation Credit; for each 1 acre foot credited an additional 2 acre feet would be relinquished to the basin (this ratio is consistent with Pahrump basin water management strategy). 2.) 1 Conservation Credit = 1 AF of water 3.) Relinquished water rights cannot be “un-relinquished”. 4.) Participation in the Conservation Credit Program is voluntary. 5.) State of Nevada DWR manages the Conservation Credit Program.

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6.) Water rights held within the Conservation Credit Program would be exempt from filing extensions of time, forfeiture and cancellation for non-use. 7.) Permitted and/or certificated water rights are allowed in the Conservation Credit Program and are encouraged (to control overall pumpage inventory). 8.) Water rights held in the Conservation Credit Program would be exempt from further over dedication. This requires revision to County code to acknowledge that water rights have been relinquished in appropriate ratios. 9.) Water rights held within the Conservation Credit Program maintain their priority date, therefore are subject to curtailment. 10.) Owners of water rights participating in the Conservation Credit Program would be required to report point of diversion, place of use and amount of use (meter readings). 11.) Water rights held within the Conservation Credit Program would be subject to all other Nevada statutes governing water. 12.) The Conservation Credit Program would not apply to overall Nevada water law, only to basins designated as Critical Management Areas or with DWR approved Ground Water Management Plans.

As part of the research on this item staff spoke with various owners of water rights in the Pahrump basin, the State Engineer and his staff, Assemblyman Oscarson and Senator Goicoechea regarding the conservation concept. Staff also participated in legislative hearings and workshops regarding SB 81. In general, the above definition has received favorable comments from DWR staff and language that would allow the concept as part of a GWMP was added to SB 81 for consideration in the 2015 legislative sessions. Due to the required change to Nevada water law and taken together with the notion that relinquishment ratios will be tailored basin to basin to target specific goals, the April 7, 2015 version of SB 81 with regard to the conservation concept read:

(Excerpts from SB 81) “Exempt a water right from the requirements set forth in NRS 533.390, 533.395, 533.410 and 534.090 during the period that the plan is in effect so that any conservation practices that are implemented do not result in the cancellation or forfeiture of a water right.” …and… “Authorize the voluntary relinquishment to the source of a portion of a groundwater right in exchange for granting an exemption on the unrelinquished portion of the groundwater right from any provision that requires the filing and approval of extensions to avoid the cancellation or forfeiture of the groundwater right during the period that the plan is in effect. Any right that is not voluntarily relinquished is not exempt from regulation by priority.”

Because SB 81 did not materialize in 2015, it is unknown; a.) If some form of the bill will be included in the 2017 legislative session, or b.) If the bill language will be modified for future consideration.

The GWMPC recommends: That the Conservation Credit Program be pursued in some form in the 2017 legislative session. A Conservation Credit Program as outlined previously in this section has the potential to control pumpage inventory and significantly reduce over allocation of water rights in Basin 162 through the relinquishment process.

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(K) - Development Agreements

The Pahrump high growth years of the early and mid-2000’s resulted in eleven approved development agreements for high-density residential subdivisions. The subsequent recession delayed the construction of most of the total of 19,895 homes planned in these agreements – less than 800 have actually been built.

At the existing lot density of the agreements, the remaining 19,000+ homes would result in a population increase of approximately 45,000 people - more than doubling our 2015 Pahrump Valley population of 38,929. Growth at that density would consume close to an additional 9,000 acre feet of water annually - most of it concentrated in the South-East portion of the Valley.

In recognition of the valley’s already existing 27,000+ vacant residential building lots, the Groundwater Management Plan seeks to understand the impact that existing and potential additional subdivision development agreements would have on the basin’s limited water supply.

Residential cluster development is the grouping of residential properties on a development site in order to use the extra land as open space (shared community space, parks, etc.) This type of development could potentially result in water savings over existing subdivision development agreements; however, quantification of the potential savings is required.

The GWMPC recommends:

1.) To implement the density reduction policies of the Pahrump Master Plan Update (approved in December 2014) into specific NCC code requirements for new development agreements. 2.) The Pahrump Regional Planning Commission modify the zoning category VR-8 (8,000 sq. ft. minimum lot size). 3.) Define and quantify the potential water savings from Cluster Development over existing subdivision agreements. 4.) Large developments should be required to: a.) Provide a Water Conservation Plan that commits to conservation measures and b.) Provide CC&R requirements that promote water conservation, c.) Provide an overall estimate of that development’s yearly water usage. 5.) The Nye County Planning Department: a.) Update the January 2012 “Report on Status of Development Agreements” and b.) During that update, Nye County is asked to informally work with each developer to encourage them to voluntarily reduce the overall water consumption of their project’s design.

(L) - Growth Control

This item as discussed by the GWMPC recommends investigation into any and all items that might improve the balance between available water resources and available lands for development. The committee sees growth to a full build out population of 495,000 or more (as presented in previous versions of the Pahrump Master Plan) as an unreasonable expectation. The 2014 Pahrump Master Plan Update policies (Appendix J) have the potential to reduce the full build out population to approx. 103,000 (as compared to previous versions of the

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Master Plan), but a population of 80,000 at 198 gpcd, approaches a point that little water is budgeted for irrigation.

It is expected that agriculture in the Pahrump basin will continue to give way to development, but there will always be a need for open space, parks, and other water uses besides housing. Re-use of water for irrigation of golf courses or other enterprise will certainly become more attractive as the community grows and water rights become increasingly scarce. When considering the importation section of this report; importation and growth are married one to the other simply based on the vast amount of available lands in the Pahrump basin for future development.

Table 4 presents gpcd v/s population. Notice from the table entries highlighted in gray that a future population of 80,000 in the 200 gpcd column (the conservation usage target) requires approximately 18,000 AFA of water. For a perennial yield of 20,000 AFA, this leaves 2,000 AFA of water for irrigation. Water re-use, RIBS and subsequent recharge credits could provide a buffer and improve the overall water budget outlook for irrigation uses. The dashed line in Table 4 shows what the sustainable population limit would be for gpcd usage figures other than the 200 gpcd. For example, if we don’t reduce today’s average gpcd usage below 250 gpcd, that same 18,000 AFA of water pumping can only sustain 65,000 people – not 80,000.

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Table 4: Water usage by population at different Gallons Per Capita Day (gpcd) Rates (W. Kuver)

Pahrump Total Water Usage (in AFY) at Different Gallons Per Capita Per Day Rates Population 150 gpcd 200 gpcd 225 gpcd 250 gpcd 275 gpcd 300 gpcd 325 gpcd 350 gpcd 375 gpcd 400 gpcd 425 gpcd 450 gpcd 475 gpcd 500 gpcd

25,000 4,201 5,601 6,301 7,001 7,701 8,401 9,101 9,801 10,501 11,201 11,902 12,602 13,302 14,002 27,500 4,621 6,161 6,931 7,701 8,471 9,241 10,011 10,781 11,551 12,322 13,092 13,862 14,632 15,402 30,000 5,041 6,721 7,561 8,401 9,241 10,081 10,921 11,762 12,602 13,442 14,282 15,122 15,962 16,802 32,500 5,461 7,281 8,191 9,101 10,011 10,921 11,832 12,742 13,652 14,562 15,472 16,382 17,292 18,202 35,000 5,881 7,841 8,821 9,801 10,781 11,762 12,742 13,722 14,702 15,682 16,662 17,642 18,622 19,603 37,500 6,301 8,401 9,451 10,501 11,551 12,602 13,652 14,702 15,752 16,802 17,852 18,902 19,953 21,003 40,000 6,721 8,961 10,081 11,201 12,322 13,442 14,562 15,682 16,802 17,922 19,042 20,163 21,283 22,403 42,500 7,141 9,521 10,711 11,902 13,092 14,282 15,472 16,662 17,852 19,042 20,233 21,423 22,613 23,803 45,000 7,561 10,081 11,341 12,602 13,862 15,122 16,382 17,642 18,902 20,163 21,423 22,683 23,943 25,203 47,500 7,981 10,641 11,972 13,302 14,632 15,962 17,292 18,622 19,953 21,283 22,613 23,943 25,273 26,603 50,000 8,401 11,201 12,602 14,002 15,402 16,802 18,202 19,603 21,003 22,403 23,803 25,203 26,603 28,004 52,500 8,821 11,762 13,232 14,702 16,172 17,642 19,112 20,583 22,053 23,523 24,993 26,463 27,934 29,404 55,000 9,241 12,322 13,862 15,402 16,942 18,482 20,023 21,563 23,103 24,643 26,183 27,724 29,264 30,804 57,500 9,661 12,882 14,492 16,102 17,712 19,322 20,933 22,543 24,153 25,763 27,374 28,984 30,594 32,204 60,000 10,081 13,442 15,122 16,802 18,482 20,163 21,843 23,523 25,203 26,883 28,564 30,244 31,924 33,604 62,500 10,501 14,002 15,752 17,502 19,252 21,003 22,753 24,503 26,253 28,004 29,754 31,504 33,254 35,004 65,000 10,921 14,562 16,382 18,202 20,023 21,843 23,663 25,483 27,304 29,124 30,944 32,764 34,584 36,405 67,500 11,341 15,122 17,012 18,902 20,793 22,683 24,573 26,463 28,354 30,244 32,134 34,024 35,915 37,805 70,000 11,762 15,682 17,642 19,603 21,563 23,523 25,483 27,444 29,404 31,364 33,324 35,285 37,245 39,205 72,500 12,182 16,242 18,272 20,303 22,333 24,363 26,393 28,424 30,454 32,484 34,514 36,545 38,575 40,605 75,000 12,602 16,802 18,902 21,003 23,103 25,203 27,304 29,404 31,504 33,604 35,705 37,805 39,905 42,005 77,500 13,022 17,362 19,533 21,703 23,873 26,043 28,214 30,384 32,554 34,724 36,895 39,065 41,235 43,406 80,000 13,442 17,922 20,163 22,403 24,643 26,883 29,124 31,364 33,604 35,845 38,085 40,325 42,565 44,806 82,500 13,862 18,482 20,793 23,103 25,413 27,724 30,034 32,344 34,654 36,965 39,275 41,585 43,896 46,206 85,000 14,282 19,042 21,423 23,803 26,183 28,564 30,944 33,324 35,705 38,085 40,465 42,846 45,226 47,606 87,500 14,702 19,603 22,053 24,503 26,953 29,404 31,854 34,304 36,755 39,205 41,655 44,106 46,556 49,006 90,000 15,122 20,163 22,683 25,203 27,724 30,244 32,764 35,285 37,805 40,325 42,846 45,366 47,886 50,406 92,500 15,542 20,723 23,313 25,903 28,494 31,084 33,674 36,265 38,855 41,445 44,036 46,626 49,216 51,807 95,000 15,962 21,283 23,943 26,603 29,264 31,924 34,584 37,245 39,905 42,565 45,226 47,886 50,546 53,207 97,250 16,340 21,787 24,510 27,233 29,957 32,680 35,404 38,127 40,850 43,574 46,297 49,020 51,744 54,467 100,000 16,802 22,403 25,203 28,004 30,804 33,604 36,405 39,205 42,005 44,806 47,606 50,406 53,207 56,007 102,500 17,222 22,963 25,833 28,704 31,574 34,444 37,315 40,185 43,056 45,926 48,796 51,667 54,537 57,407 105,000 17,642 23,523 26,463 29,404 32,344 35,285 38,225 41,165 44,106 47,046 49,986 52,927 55,867 58,808 107,500 18,062 24,083 27,093 30,104 33,114 36,125 39,135 42,145 45,156 48,166 51,177 54,187 57,197 60,208 110,000 18,482 24,643 27,724 30,804 33,884 36,965 40,045 43,126 46,206 49,286 52,367 55,447 58,528 61,608 112,500 18,902 25,203 28,354 31,504 34,654 37,805 40,955 44,106 47,256 50,406 53,557 56,707 59,858 63,008 115,000 19,322 25,763 28,984 32,204 35,425 38,645 41,865 45,086 48,306 51,527 54,747 57,967 61,188 64,408 117,500 19,743 26,323 29,614 32,904 36,195 39,485 42,775 46,066 49,356 52,647 55,937 59,228 62,518 65,808 120,000 20,163 26,883 30,244 33,604 36,965 40,325 43,686 47,046 50,406 53,767 57,127 60,488 63,848 67,209 122,500 20,583 27,444 30,874 34,304 37,735 41,165 44,596 48,026 51,457 54,887 58,317 61,748 65,178 68,609 125,000 21,003 28,004 31,504 35,004 38,505 42,005 45,506 49,006 52,507 56,007 59,508 63,008 66,509 70,009 127,500 21,423 28,564 32,134 35,705 39,275 42,846 46,416 49,986 53,557 57,127 60,698 64,268 67,839 71,409 130,000 21,843 29,124 32,764 36,405 40,045 43,686 47,326 50,967 54,607 58,247 61,888 65,528 69,169 72,809

The GWMPC recommends:

1.) Water-related policies within the 2014 Pahrump Master Plan (Appendix J) should be implemented and included within County Code.

2.) Mitigation of water at a ratio of “2 AF relinquished or mitigated -to- 1 AF to be placed to use” for future commercial and industrial development be required.

32 | Page

3.) Continued investigation into any and all items that might improve the balance between available water resources and available lands for development.

4.) Resolution of: a.) Current and future potential of over dedication for subdivisions and parcel map applications, b.) Current and future potential for direct effluent reuse and c.) Current and future potential for recharge credits associated with RIB’s.

(M) – Additional Recommendations

This version of the Ground Water Management Plan is considered by the Committee to be a living document - or- Stage One of a long term effort to create a plan for the Pahrump Basin that balances water supply with demand for the future. It is the express desire of the Committee that the WDGB, BoCC and DWR accept this plan as presented and utilize the recommendations contained herein to implement the plan and where appropriate, amend County Code and NRS in support of the plan.

The GWMPC has considered more than 180 individual items over 20 months of public meetings. Attached in Appendix K is a spreadsheet showing the list of items considered by the committee that provides respective rankings, recommended plan Stage and includes miscellaneous comments. Items for Stage 2 of the GWMP (like Stage 1) will either be considered for implementation by the BoCC, by the WDGB, or for GWMPC consideration should the BoCC ask the committee to continue working on the plan in the future.

We need to continue to work with the State Engineer and his staff to provide an accounting for how each section of the plan will reduce over allocation of water rights and increase usable water resources. This accounting is the essence of the Plan and when completed (in report form) will provide some sense of priority for the host of projects as outlined.

This accounting (in report form) will provide the following:

1.) The potential for water conservation as outlined in the Plan, in terms of Acre Feet Annually (AFA).

2.) The potential to increase usable wet water such was re-use of effluent and/or use of RIBs for recharge as outlined in the Plan, in terms of AFA.

3.) A total for existing over-dedication of water rights and estimates of the potential for over-dedication of water rights to reduce the amount of water rights on the books as outlined in the Plan, in terms of AFA.

4.) The total potential for each section in the Plan, in terms of AFA.

GWMPC members and Water District staff have begun to work on the above 4 items. The effective implementation of this Plan will be a measure of: a.) available funding, b.) constructive interaction with the State Engineer and his staff and c.) the desire of our community and elected/appointed officials to support this effort.

33 | Page

Basin 162 Historical Reports USGS

Other reports of potential interest which are not included in the appendix:

In 1982 US Geological Survey’s Open-File Report 81-635 “Groundwater Storage Depletion in Pahrump Valley, Nevada-California, 1962-1975”, by James R. Harrill was prepared cooperatively by the Nevada Department of Conservation and Natural Resources and the US Department of the Interior, Geological Survey. This Report is available on the USGS website at http://pubs.er.usgs.gov/publications/wsp2279 .

Geological Survey Professional Paper 712-C “Hydrogeologic and Hydrochemical Framework, South-Central Great Basin, Nevada-California, with Special Reference to the Nevada Test Site” was prepared by the US Department of the Interior, Geological Survey. This report is available in the office of the State Engineer.

Geological Survey Water-Supply Paper 1832, “Hydrology of the Valley-Fill and Carbonate-Rock Reservoirs, Pahrump Valley, Nevada-California”, was prepared in cooperation with the Nevada Department of Conservation and Natural Resources and the US Department of the Interior, Geological Survey. This report is available on the USGS website at http://pubs.er.usgs.gov/publications/wsp1832 .

Water Resources Bulletin No. 5, “Geology and Water Resources of Las Vegas, Pahrump and Indian Springs Valleys, Clark and Nye Counties, Nevada”, was prepared by G. B. Maxey and C. H. Jameson. This report is available for review at the office of the State Engineer.

34 | Page

Appendix B Soil Maps “Fines Content of Soils within the Pahrump Regional Planning District, Nye County, Nevada”, Nye County Natural Resource Office, January 2014.

“Soils and Geotechnical Map – Pahrump Regional Planning District”, Tri-Core Engineering, June 2004

GOLDEN

BANDIT

AARDVARK

LINDA ANCHOR

MAX

MONARCH

NEIL ALFRED

MIA

BAT

LEANNA

MOUNTAIN VIEW MOUNTAIN OHIO

ZIRCONIA IRVING

RUBY AMETHYST LAPIS

SAPPHIRE MIA NELLIE GOPHER

BLAGG SISSON LAST CHANCE

PASCOE

BOA NEIL MAZZUKA CLAIRE MAZZUKA

BECKY

SUMMER BLACK ROCK BLACK

MIRANDA ROB ROY ROB

STEALTH CREST

ROADRUNNER

BURT DEVIN

BENDER TIFFANY

ZEBRA

KOALA Ash Meadows AUSTIN MIRIAM MIRIAM ANDERSON r PATHWAY

GAHN CARROL PARQUE KYLE LAURA MAE AZUL AURA JENT AURA

GLENCOVE BEN

MOSES SHARPE BLACKROCK

ALCOVE COLINA LINDA QUINCE

CABOT GENOA KENS

CLINE ELGIN EVA KILTY PYRAMID ZORRO Bell Vista SERENITY ANNIE HOLLY

HARRIS FARM RONNIE RUSTY LATIGO WOODCHIPS SLOAN BUCKEYE MORONGO CORDOVA SUNBURST NYE DESERT FRONTIER LOLA GORGONO

PALM PIONEER SILVER SAGE

SIMKINS FAN

POINT

JOANITA

MACK STEPHANIE TONYA JARVIS ARABY

CORBIN JENNY KELISHAN

GARRISON GALLY MIKE BUNARCH INTERCEPTOR NICHOLAS SCALES GAY

BARNEY BELL VISTA

POWERLINE

ZOE

QUAIL RUN PAR ANZA

RITA

CHOLLA

CABO

BLOSSER RANCH BLAGG

TOUGH BOY NADINE EFFINGER GRETA BV HYDE HELICOPTER

BALZAR OF THE STARS THE OF

WARREN

MESQUITE LAKODA PEARL

LESLIE UTAH JILL

CHICO ADKISSON

WHITEHAWK CINDY

BASS DAVID BEVS PROMENADE

CORBIN

BAKER HIGLEY OUR ROYAL

OUR KITTYHAWK

MURPHY IRENE

CORBIN WHEELER PASS PILTZ DELTA GERTRUDE

RICHARD DANA BAKER JODI

SHADY LOLA LYNN HELEN BLACK

BETTY BETTY BETTY PANORAMA MARIE WHITNEY HALO PINK KYLE INGOT CHRISTIAN DOUG

EMERALD EMERALD FERN

WARREN ALASKA DOVE BASIN BASIN OYSTER

EMERY

KIM DANNER ASH MEADOWS DYER JUDY FORD HORN

SPRUCE WHEELER PASS DONNER JEWELL LONG WILSON RETREAD IRONS

MEDICINE MAN HAPPY FRIDEL 4TH FIREBIRD

HARDY HARDY BUOL

BIG 5 BIG CHARLESTON PARK CHARLESTON PARK ASPEN BOURBON POSTAL VAN MANITOBA CAVE

BANNAVITCH RED BUTTE INDUSTRIAL MAPLE ZELZAH HONEYSUCKLE

MEIER BUTLER TIPTOP UPLAND CORTINA PARSONS

FAWN OLD WEST

CALVADA BV EQUESTRIAN

VISTA FLAMINGO XENIA AMBUSH PAGE GALAXY

NEVADA RT 372 MOOSE LAGUNA LUPIN

MANDY VENUS WINDY IDLEWILD RAINBOW

BELT ZEPHYR CHINA GINA ZUNI VENZA HICKORY

RED ROCK RED MARIPOSA DANDELION JAYBIRD INDOLE LEXIS Z CAVALRY PICO DEERSKIN MURPHY STARLIGHT

BLAKE

PRAIRIE

OAKLEAF NESS Nevada Rt 372 REBEL

LESLIE PANHANDLE PAHRUMP

EMBER UNICORN

JOLLIE

BIG SKY BIG

CATHI

KID

TAHACHAPI RAVINE

GAMEBIRD FOX NEWBERRY

WINCHESTER PIOCHE

HOLIDAY SANDY

WHISTLER KID PLUTO CARPENTER CANYON JEANE

CARBERRY JACKIE CAAS ALFANO MANSE MANSE

CASEY EBERHARD

MALIBOU MICKEY LORELI JULIE DELANEY

COFFIEANN

ZOLIN MONEY

GILLS

PLANTATION VICKI ANN VICKI

JENNIFER MOJAVE

CARSON OAKRIDGE

BRIDGER FIELDSTONE RANCH HAFEN

PAULA KINGS NYE CLARK NYE KEENAN KENT EBERHARD

KELLOGG SPRINGS RADIUM

CAJON NAVAJO BV NEVADA RT 160 JANE

MCGRAW FOX WARD PRPD Boundary PAWNEE PRPD Soils TURNER BV INDIAN RESERVATION

KISHA FOX RoadCenterline Fines Content HORSE QUARTER

THORNE HOMESTEAD SUPERIOR

RoadCenterline High BOND BOND MONICA KEITH

TILLMAN HILVA SILVER Low SHIRLEY TRACI No Data Old Rt 16

BISMUTH HAFEN RANCH HAFEN

Map Date: January 29, 2014 FRONT SITE 01 2 4 6 8 Source: NRCS Soils Data FRONT SITE BV Contact: Levi Kryder Miles Nye County Natural Resources Office PANACA

775-727-7727 | [email protected] MABES HAFEN RANCH HAFEN KLONDIKE HUXLEY TUSCARORA Hidden Hills

Tecopa Rd EBERHARD WEEPAH

TUNGSTEN BV

Fines Content of Soils within the Pahrump COUNTYLINE

Regional Planning District, Nye County, Nevada EUROPIUM LEAD 2054 2301 2005 2810 2870 2810 2061 2080 2810 2140 2930 2870 2080 2061 2434 2080 2301 2391 2870 2990 2152 2301 2140 B-01 2434 2434 2870 2080 2434 2080 2920 B-02 2152 2920 2140 2301 2080 2880 2301 2005 2050 2301 2060 2060 2301 2152 2434 2880 2152 2054 2870 2060 2080 2930 2880 2140 2010 2860 B-04 B-03 2060 2930 2870 2434 2152 2080 2930 2434 2005 2870 Carrol St 2010 2005 Carrol St 2060 2930 2434 2080 2057

MountainView 2930 B-05 2434 Unnamed 2860 B-07 2080 LindaSt 2060 Leslie St B-08 2152 Leslie St B-06 Unnamed 3320 2930 2870 Linda St Genoa Av 2060

LindaSt Leslie St 2061 2080 B-11 2080 2080 B-09 B-10 2220 2061 2080 2860 2005 3101 Bell Vista Av 2080 3333 Panorama Rd 3101 20802080 2860 B-17 3101 B-12 2870 2950 3313 Palm Dr Lola Ln Ash Meadows Rd 3101 2110

2080 Blagg Rd B-13 Krysta Ln Jake Ct 2010 2080 Jenny Cr 2080 2870 Cabo St 2023 CorbinSt B-14 B-15 Bell Vista Av 2050 2057 B-16 2080 Bell Vista Av 2057 B-49

2870 Unnamed 2080 2005 2080 B-21 Rd Blagg B-18 B-20 3101 2057 Bell Vista Av Bell Vista Av Bell Vista Av Bell Vista Av Bell Vista Av Bell Vista Av 2050 2010 2950 B-19 B-29 2054 B-22

Barney St Ash Meadows Rd B-25 Rd Blagg 2005 Mesquite Av Mesquite Av B-24 B-26 Mesquite Av 3101 B-27 2010 2050 B-23 Leslie St Leslie St Leslie 2080 Quinn Ct B-28

BarneySt Adkisson St 3333 3333 Stagecoach Rd 2050 2080 B-32 3101 2110 B-33 3302 LeslieSt Irene St B-36 Irene St Irene St 2080 3101 Baccarat Cr 2900 Ash Meadows Rd 3313B-30 Shady Ln B-35

2057 DavidSt 3302 LeslieSt 2050

B-37 Karis Ln Blagg RdBlagg 3101 2054 2870 B-39 B-40 2950 B-34

B-38 Dahlia St Basin Av Basin Av Basin Av Basin Av Basin Av Basin Av Basin Av Basin Av Basin Av Basin Av B-31 B-413101 2950 2152 Ash Meadows Rd 3302 2110 2054 B-42 Wilson Rd Wilson Rd Wilson Rd Wilson Rd 3101 Buol Rd 2050 2050 2005 Big 5 Rd 2110

Lola Ln 2005 St Leslie B-44 Fifth St

B-46 StBunch 2110

Charleston Park Av Charleston Park Av B-47 Rd Blagg 2050 2950 B-48 Postal Dr

Red Rock Dr Rock Red

B-45 StLeslie B-56 Manitoba St Daytona St B-93 Ivy Ln Bv Valley Pahrump B-43 3302 St Dandelion 2950 2054 Rio Rico Dr Loop Rd 2110 2010 2080 B-60 B-55 Calvada Bv B-53 Vineyard Dr 2080 3302 B-54 Blagg Rd Belville Rd Winery RdB-51Winery Rd Explorer Ln 3333 2054 B-57 B-58 B-50 B-97 B-52 2010

Ash Meadows Rd Blagg Rd 2057 Calvada Bv Idaho St 3313 2110 2220

Malibou Av Legend RedRock Dr B-61 3313 2950 2080 B-62 B-63 B-64 B-77 B-65 Pico St B-80 B-81 B-59 Jaybird St Av Rainbow B-66

Soil Types Rainbow Av

Bride St 2218 B-68

Blagg Rd Blagg 3320 4071, Corbilt Av Winchester 3313 B-78 B-72 Unicorn Av Unicorn B-71 2054 2080 Homestead Rd 2080 4060 Av Malibou 2110 4060, Besherm-Tanazza B-69 3302 B-67 B-70 Gamebird Rd B-74 3101 4030, Wechech-Nopah-Yermo 4060 B-73 B-75 3333 B-76 3313 3313 3302 2110 B-82

Homestead Rd

4010, Tanazza-Wechech-Wodavar Rd Ann Vicki 4060 3302

B-79 St Money C.A.A.S. Rd 3333, Nopah

Batdorf Ct Manse Rd Manse Rd Manse RdManse Rd Manse Rd 3320, Haymont 3302 Rd Ann Vicki B-86 33133313 4060 Rd Hafen Ranch 3302 3333

Clark St Clark

Corrine St Corrine 3313, Besherm St Bonnie Zolin Av 33023313 Ct Tribett B-87 3302, Rumpah 3313 B-85 B-90 4010 Thousandaire Bv

2630 B-84 DanielleCt 3101, Bluepoint-Besherm Grain Mill Rd B-83 2054 2990, Lealandic-Ashmed Saddletree Rd 2630 Santovito St Santovito St 2110 2950, Pits 4060 4060 B-88Kellogg Rd Kellogg Rd Kellogg Rd Kellogg Rd Navajo Bv Navajo Bv B-89 2312 Paiute Bv Paiute Bv 2930, Seralin-Rock Outcrop-Sed McGraw Rd

2920, Dumps 3313 Ward Ct 2220

2630 B-91 Turner Bv 31013101 2900, Playas 3313 4010 3333 31013101 2880, Bacho-Yermo-Arizo 3313 Homestead Rd B-92 3313 3313 2870, Kanackey 2860, Sezna-Yermo 2630 Thorne Dr 2312 SaifCt B-98 2810, Ashmed, Moist-Yermo-Niavi B-94 3333 B-96 2630, Wechech-Commski B-95 4060 Silver St 3101 2434, Cruzspring-Schader-Rock Outcrop Solubility Potential

2391, Commski-Ashmed Moderate to High Solubility Potential 4010 3320 3101 4010 2312, Commski-Tanazza Low Solubility Potential 4030 4010 2301, Tecopa-Haleburu-Rock Outcrop Expansion Potential 2220, Canoto-Arizo Moderate to High Expansion Potential 2218, Sanwell-Commski 4030 2152, Arizo None to Low Expansion Potential 2140, Jonnic-Niavi Fissures 2110, Pahrump Limit of Fissure Data 2080, St.Thomas-Tecopa-Rock Outcrop Fissure Zone 2061, Vace B-99 Fault Lines 2060, Purob-Irongold 4071 Fault Fissure Buffer 2057, Yermo-Commski 2054, Yermo, Hot-Yermo-Arizo Approximate area of potentially moisture-sensitive (settlement-prone and/or expansive) soils B-100 2050, Canoto-Naye Pahrump Regional Planning District Boundary 2023, Commski-Sezna 2010, Longjim 2005, Rock Outcrop-St. Thomas Assoc. Soils And Geotechnical Map SOURCE : U.S.D.A., Nevada Bureau of Mines and Geology and Ninyo and Moore

DATE: June 18, 2004

PREPARED BY: TRI-CORE ENGINEERING 7272 E Indian School Rd., Suite 420 Scottsdale, Arizona 85251 (480) 346-3200 fax (480) 346-3201 Miles 00.5 1 2 3 4 PAHRUMP REGIONAL PLANNING DISTRICT Appendix C

“Figure 5-1. Long Term Water Level Trends Pahrump Valley”, taken from the “Nye County Water Resource Plan ”, Giampaoli, April 2017.

Appendix D

Public Comments and Responses to Draft Report Dated May 8th 2017 Public Comments Received Name Section or Page Comment Resolution Walt Kuver Pg. 3-1 (and At some appropriate point, please In this report (refer to context), north-central- subsequent): specifically define the basin areas southern Pahrump are loosely used to Description of Basin generally designated as “North”, describe the developed portions of the Valley, Areas “Central”, and “South”, i.e.: is the roughly partitioned into thirds. They are “North” lower boundary Hwy 372? general locations within the developed Where does “Central” end and portions of the Valley associated with degrees “Southern” begin? of drawdown and the reader can infer from the corresponding exhibits rough areas. Walt Kuver Pg 3-1: Reginal Suspect its name should be Walker Yes, the name is “Lake’. Typo corrected. Walker “Lane” Fault “Lake” . . . couldn’t verify in Harrill or Malberg. Walt Kuver Page 3-2, DWR PIR When multi-year average pumping The pumpage data is presented unaltered as Pumpage Data: figures are used, be aware that the obtained from the references cited. Also, DWR annual average figure subsequent changes to the assumed pumping estimated for domestic well pumpage rates may not necessarily be “retro-active”, changed in 2009 to 0.5 AFA from the more current conservation measures and/or 1.0 AFA figure used in 2008 and local area social issues may result in lower prior PIR’s. Not sure if report figures domestic well pumping rates today than in are affected. the past. Walt Kuver Section 5 – DRI Representation of drawdown as Yes, drawdown contours have been added. Modeling Result Maps variation in colors and their shades is useful and informative at first glance but, in some cases, numerical contour lines would be easier to interpret in detail. Does the DRI Model have that capability for larger map formats?

Name Section or Page Comment Resolution Walt Kuver Section 9 – Perhaps it This is a potential option worth further consideration, but with the information Artificial would be currently available the determination of the cost versus benefit from physical Recharge – more directly infrastructure cannot be determined to the level deemed needed within the scope (Consider an effective of this report. In addition, existing utility information was limited to public Additional (and a lot less reports while specific operational information was not provided (primarily Perspective) expensive) to hydraulic models and electronic mapping). Specifics on locations of utility locate AR trunk lines and available capacity/PSI for recharge were not provided. Also, a injection project of this nature would likely need to be multi-faceted to be feasible (achieve AR, support future growth and capture domestic well conversions), so wells directly prior to proceeding with AR planning it is recommended to map the domestic in the well locations in addition to added refinement of the DRI flow model. “orange” areas of With the above being said, this option was considered conceptually, but there are drawdown no existing municipal supply wells that are outside of the basin fill/transition and supply zone that are good recharge source candidates. Ideally, we would like to have a them with source that is independent of the aquifer being recharged, or spatially located far potable enough away to globally disperse drawdown. Also, there would be no net water increase in annual basin recharge, it will take more utility well pumping (1:1) to purchased by have excess supply for recharge. In addition, more studies are needed to the Water determine the feasibility and potential benefit/impacts to localized drawdown District from from injecting at the locations in the “orange”. A potential site specific concern the nearest that needs to be evaluated prior to planning injecting facilities is ground existing subsidence may have resulted in reduced soil transmissivities, so areas of utility trunk greatest drawdown may have limited capacity for recharge (may be better off line. Might recharging larger amounts up or down gradient from these locations). It is recommended to complete the refinements needed to the DRI flow model and also be a way map all domestic wells to their corresponding parcel. Once these tasks are to retire completed, in conjunction with cooperation from area utilities a better analysis some utility‐ of cost versus benefit can be made. In the end, the cost-benefit of this effort will held water boil down to comparing the facility/rights/permits cost for AR improvements rights. against the cost savings achieved by preventing re-deepening an estimated number of domestic wells that benefit from AR. Name Section or Page Comment Resolution

Walt Kuver Section 10 and Section 12 (# Be aware that there are a Per 2015/16 utility service of ISDS installations significant number of lots with connection information utility water service but obtained there were 5,861 Individual ISDS systems – water and 4,264 sewer ISDS figures do not strictly customers, resulting in correlate 1:1 with domestic approximately 1,597 municipal well counts. Perhaps the water customers with septics. utilities have the data as to how We added the 1,597 water many – at any rate, these ISDS customers with septics to the incidences should be mapped to estimated number of domestic the parcel level along with wells (11,000) to get domestic wells. approximately 12,597, which was used to check/confirm the 12,400 ISDS number provided by NCWD used in this report. Walt Kuver Section 12.3-Pharmaceuticals The discussion of WWTP A discussion regarding ISDS potential issues with and pharmaceuticals was pharmaceuticals should be added into Section 12.3 grounded with a reminder that the sheer number of untreated ISDS installations (as in the case of nitrate discharge), overwhelms whatever concerns might linger over WWTP discharge of pharmaceuticals.

Name Section or Page Comment Resolution

NDWR Section 1.0, page 1-1, 2nd Change “The sustainable Change made for final draft. paragraph pumping perennial yield is on the order of 10,000 AFA….” to “The sustainable pumping rate based on the present well configuration on the order of 10,000 AFA….” NDWR Section 2.0, page 2-1, 2nd Change “…groundwater Change made for final draft. paragraph withdrawl is 72,206 AFA resulting in an over allocation on the order of..” to “…groundwater withdrawl is 72,206 AFA resulting in an over draft on the order of..” NDWR Section 2.0, page 2-1, 2nd Because the of over Agreed, clarifying statement paragraph dedications by the utilities, the added. likelihood of 72000 af of pumping is nil. This sentence does not represent actual conditions. NDWR Section 2.0, Table 2-1: In Of this amount, 7807 af of The amount of permitted water regards to the “Existing Dom rights are relinquished rights was provided by Permitted Water Rights listed for domestic wells, unknown NCWD, while the amount of of 59,303. how many of these have relinquished rights (also actually been drilled, assume provided by NCWD) is listed most. I suggest you use 51,496 separately in Tables 10-4 and here, and retabulate this table 10-5 where they are deducted and text above. from the permitted.

Name Section or Page Comment Resolution

NDWR Section 4.0, pg 4-2: In regards How was this number derived? The number is based on a to septic system return flow of What is recharge per septic? return flow of 150 gpd/ISDS 2,084 AFA. times the 12,400 estimated septics. The return flow per ISDS was based on review of area utility return flows and septic return flow estimated from studies conducted in Nevada. The second paragraph in Section 8.2 discusses how the ISDS return flows were derived. NDWR Section 9.0, pg 9-1: In regards no negotiations are pending This was conveyed in a phone to the 85 percent in-lieu conversation with LVVWD recovery credit for LVVWD staff, but will be changed accordingly per the hierarchy of the source. NDWR Section 10.0, pg. 10-3. We don't have a perennial Sustainable pumping yield for any specific part of perspective is used to the basin or specific aquifer. condition the “Perennial Just one, and it's for the entire yield”, but that can be deleted basin. 'Perennial yield' has a and utilize the single very specific meaning. statement, “sustainable Perhaps you could use pumping rate for the basin fill 'sustainable pumping rate' or aquifer”. even 'sustainable yield'.

Name Section or Page Comment Resolution MaryEllen C. Giampaoli Sections 5 and 10 In regards to concern that the Clarification text has been modeled pumping level being added in Section 5 to explain higher than forecasted (2060) how we believe the drawdown is the predicted drawdown predictions are accurate for an accurate? annual increase of 1.5% in consumptive use. The larger volume of water pumped in the current model is compensated for with higher specific yields.