Park City and Snyderville Basin Water Supply Study Special Report 

4-1 

Chapter 4 – Future Supply & Demand and 

Projected Needs 

4.1 Introduction 

This chapter presents the process used to determine future water demands and projected needs 

within the study area. It includes a discussion of population projections, determination of future 

demands, and calculation of future supplies which are assumed to be available without 

implementing any of the supply components described in Chapter 5. From this data, conclusions 

were drawn about projected water needs for 2030 and 2050. 

4.2 Population Projections 

Two different methodologies for projecting future population were considered: The Governor’s 

Office of Planning and Budget (GOPB), in conjunction with local Area of Governments (AOG), 

is the agency responsible for preparing population and other demographic projections for the 

State of Utah. In May 2005, the Mountainland AOG broke down the latest Governor's Office of 

Planning and Budget population projections for Summit County by incorporated cities and towns 

with the remainder as the balance of county. The city projections include Park City’s estimated 

population for each decade from 2010 through 2050. Using this data and the 2000 Census tract 

data as a guide to future population distribution, the population of the study area in 2030 was 

estimated to be 64,300. For 2050, the projected population was estimated to be 86,300. Table 4-

1 contains the GOPB population estimates for the study area. 

The other approach taken to forecast population for the study area was to consider the maximum 

potential development within the Basin. Summit County has adopted a land use plan 

(Snyderville Basin General Plan) that identifies where development will be permitted and how 

densely it will be allowed to develop. Park City also has a similar land use plan that establishes 

the projected densities within the city limits. Using the densities associated with each land use, 

populations at build out were estimated for the various land use categories. 

Comparatively, the two methods produced somewhat different results. While the GOPB 

projections estimate a study area population of approximately 86,300 by 2050, the build out 

method estimated the ultimate population within the study area to be only 75,600. Although the 

build-out method is often useful for planning purposes, this method assumes that current zoning 

laws and associated population densities will remain unchanged for the next 45 years. As 

experience in other communities demonstrates, zoning laws can and do change when property 

values increase and pressures mount to accommodate growth. Therefore, the higher GOPB 

population estimates were not considered unreasonable and are used for the purposes of this 

study. 
Park City and Snyderville Basin Water Supply Study Special Report 

4-2 

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

2001 2010 2020 2030 2040 2050

Year

Acre-Feet

w/o Conservation

With Conservation

4.3 Projected Future Demands 

4.3.1 Demand Modeling 

UDWR has developed the Utah Water Demand/Supply model to project the future water 

demands. UDWR’s base water use data for the year 2001 and the GOPB population projections 

were used to estimate water demands within the study area for each 10-year period from 2010 to 

2050. These demands were projected both with and without water conservation. Figure 4-1 

shows the projected demands with and without conservation. 

FIGURE 4-1 

Projected Future Water Demands 

TABLE 4-1 

Snyderville Basin Population Projections

Population 

City/Area 2001 2010 2020 2030 2040* 2050* 

Park City 7,647 10,987 15,339 19,776 19,325 20,904

Balance of Snyderville Basin** 16,212 23,002 34,320 44,541 55,303 65,423

TOTAL 23,859 33,989 49,659 64,317 75,603 86,327

Source: Governor’s Office of Planning and Budget, “2005 Baseline City Projections,” June 2005. 

* The Governor's Office of Planning and Budget (GOPB) models projections to 2030, all projections beyond this date 

are estimated using other methods and are provided by GOPB for scenario analysis. 

** Estimated based on 2000 Census population distribution. 
Park City and Snyderville Basin Water Supply Study Special Report 

4-3 

Table 4-2 shows the projected demands for Park City and the rest of the Snyderville Basin for 

each 10-year increment without water conservation. Table 4-3 shows the projected demands for 

Park City and the rest of the Snyderville Basin for each 10-year increment with water 

conservation. The total water demand in 2030 without conservation is projected to be 25,300 

acre-feet. With conservation, the 2030 demand decreases by about 2,300 acre-feet to 

23,000 acre-feet per year. Projections for the year 2050 are similarly calculated. The total water 

demand in 2050 without conservation is projected to be 32,000 acre-feet. With conservation, the 

2050 demand is projected to decrease by about 5,000 acre-feet to 27,000 acre-feet per year. 

Figure 4-2 compares the 2030 and 2050 demands (with conservation) to the current demand, 

basin safe yield, and available supply as estimated in Chapters 2 and 3. 

Several water suppliers within the study area have indicated that using population-based demand 

projections to project future demands is problematic. Many have suggested that an equivalent 

residential connection method would be more appropriate. One reason for these concerns is the 

fact that a large segment of the water use in the area comes from a non-permanent or transient 

population (tourists, second homeowners, etc.). Another concern is that large landscape water 

use such as golf courses cannot be properly reflected in population-based units (such as gallons 

per capita per day). After carefully considering each of these concerns, UDWR determined that 

the methodology employed by the Utah Water Demand/Supply model adequately addresses 

these issues and there is little risk that the resulting water use projections underestimate actual 

future demands. 

TABLE 4-2 

Projected Future M&I Demands (Without Conservation) 

M&I Water Demand* (acre-feet) 

City/Area 2010 2020 2030 2040 2050 

Park City 6,794 9,485 12,228 11,949 12,926

Balance of Snyderville Basin 6,975 10,198 13,108 16,449 19,052

TOTAL 13,769 19,683 25,336 28,398 31,978

* Includes 427 acre-feet of public non-community system use. See Table 3-3. 

TABLE 4-3 

Projected Future M&I Demands (With Conservation) 

M&I Water Demand* (acre-feet) 

City/Area 2010 2020 2030 2040 2050 

Park City 6,598 8,908 11,094 10,458 10,899

Balance of Snyderville Basin 6,787 9,603 11,930 14,450 16,132

TOTAL 13,385 18,511 23,024 24,908 27,031

* Includes 427 acre-feet of public non-community system use. See Table 3-3. 
Park City and Snyderville Basin Water Supply Study Special Report 

4-4 

FIGURE 4-2 

Comparison of 2030 and 2050 Demands (with Conservation) 

to Current Demand and Available Supply 

4.3.2 Water Conservation 

As demonstrated above, water conservation will play a significant role in helping water suppliers 

in the area to meet future needs. In addition to this important benefit, water conservation may 

also: 

• Conserve energy as less water needs to be treated, pumped and distributed. 

• Lessen the leaching of chemicals and other pollutants into streams and aquifers as water 

is applied more efficiently to urban landscapes and agricultural crops. 

• Reduce future stream diversions and groundwater withdrawals that would otherwise 

occur, thereby enhancing water quality, environmental and recreational functions of 

natural waterways (UDWR, 2003b). 

The State of Utah has developed a specific goal to conserve water use directly linked to M&I 

needs. This goal is to reduce per capita water demand from public community systems by at 

least 25 percent from 1995 to 2050. In the Snyderville Basin and Park City area, the 

accomplishment of this goal is estimated to be equivalent to a total decrease in demand of 

approximately 5,000 acre-feet per year by 2050. This reduction would account for a significant 

portion of the area’s anticipated future water needs. This goal is based on modeling and research 

that indicates indoor and outdoor water use can be reduced by 25 percent or more with little 

change in lifestyle. (UDWR, 2003b). 
Park City and Snyderville Basin Water Supply Study Special Report 

4-5 

Recognizing the importance of water conservation to Utah’s future, the Utah Legislature passed 

the Water Conservation Plan Act in 1999. This act requires each water retailer with more than 

500 connections, and all water conservancy districts, to prepare water conservation plans and 

submit them to UDWR. Water conservation plans are to be updated and resubmitted every 5 

years from the original submittal date. In addition to this legislative requirement, the state’s 

water funding boards require any entity requesting funds for water projects to have a water 

conservation plan in place, regardless of its size. Only five of the eight systems in the study area 

are required by law to prepare a water conservation plan. Of the three that are not required to do 

so, only High Valley Water has submitted a plan. 

Although the Water Conservation Plan Act has helped elevate the importance of water 

conservation planning in the Snyderville Basin area, water providers in the area must set strong 

water conservation goals and ensure they are met by implementing appropriate measures. If a 

significant effort to achieve water conservation goals is not made, it may be difficult to justify 

large investments in new water development projects by state and Federal Governments. 

Many western mountain resort communities have implemented stricter watering ordinances, such 

as no outside watering or using only native plants requiring no additional water on all new 

construction. If Government entities in the study area were to implement similar ordinances for 

all new construction, the conservation goals discussed above could be more easily met. The 

current per capita use for indoor residential, commercial, and institutional categories amounts to 

about 150 gpcd. With a current total water use of 317 gpcd, there is a significant potential for 

reduction of outdoor water use in the study area. 

Water conservation efforts within the Snyderville Basin have yielded significant results in recent 

years. All three of the major water suppliers within the Study area (Park City, Mountain 

Regional Water Special Service District, and Summit Water Distribution Company) have 

realized declines in total demand in the neighborhood of 25 percent in just a few years. While 

drought-related responses certainly played a significant role in these reductions, it is likely that 

residents within the Basin will maintain at least a portion of these gains into the future. In order 

to help this to happen, the conservation message will need to continue to be emphasized during 

years of normal and above normal precipitation. 

4.3.3 Wastewater Dilution Requirements 

For the Snyderville Basin Water Reclamation District (SBWRD) to meet its State Discharge 

Permit requirements for discharging its treated M&I wastewater to East Canyon Creek, it has to 

rely on a minimum stream flow for dilution of the effluent to meet the designated beneficial uses 

for East Canyon Creek. The SBWRD is considering an upgrade to its treatment facility from the 

existing “Type 1” effluent treatment to reverse osmosis in order to comply with phosphorus 

limits. The current limit for phosphorus is 100 ppb, but the state is looking at reducing the limit 

to 50 ppb. SBWRD recently completed a very costly upgrade of its treatment system to meet the 

100 ppb limit, and if this additional upgrade is necessary, it may be cheaper to purchase water for 

instream dilution flows, or to reduce its discharge volume by reuse. 
Park City and Snyderville Basin Water Supply Study Special Report 

4-6 

Under a contract with SBWRD, Kleinfelder, Inc., recently completed a flow augmentation study 

on East Canyon Creek to determine the quantity of water that would be required to maintain 

minimum instream flows to allow achievement of beneficial uses designated for East Canyon 

Creek (“East Canyon Creek Flow Augmentation Feasibility Study: Summit and Morgan 

Counties, Utah, February 2005”). That study concluded that the maximum amount of 

augmentation to meet the instream flow goals is calculated to be approximately 1,095 acre-feet, 

which would provide a minimum 6 cfs for instream flow from July through September. This 

requirement is shown in the study for the year 2030, since 2030 is the planning time frame of the 

SBWRD. As the population increases, however, an additional 500 acre-feet would be needed by 

the year 2050 for a total need of about 1,600 acre-feet in 2050. SBWRD is interested in planning 

this future demand as part of the overall long-term demand addressed by this current study. 

Including this industrial water requirement of 1,100 acre-feet for 2030 and 1,600 acre-feet for 

2050 as a part of the projected demand leaves water reuse as a potential development option that 

may be used to meet future needs. 

4.3.4 Susceptible Mine Tunnel Flows 

A large portion (approximately 50 percent) of the water used by Park City comes from old mine 

tunnels. The mining operations have ceased and the tunnels used for water supply are being 

maintained by Park City for water supply purposes. Because the tunnels are old and the 

maintenance being performed is only sufficient to keep the water flowing, if a tunnel collapse 

were to occur, the city's ability to meet peak demands would be at least temporarily reduced until 

repairs could be made or replacement sources developed. The city is also concerned that 

maintenance of the tunnels will become increasingly more difficult and expensive as the tunnels 

age and as the availability of qualified miners continues to decline. 

The tunnels also have unique water quality issues associated with their use for drinking water 

purposes. The mines are former lead and silver mines and they contain heavy metals, arsenic, 

antimony, and other potential contaminants. The city has to carefully operate the tunnel systems 

so as to limit the amount of contaminants in the water supply. It also has to treat some of the 

water from the tunnels to remove contaminants. Concern over the long-term effects of potential 

contaminants on the water supply raises issues with the reliability of these sources. For these 

reasons, the city is interested in developing 2,000 acre-feet of additional supply to provide 

backup in case of emergencies even though they are expected to continue using the mine tunnel 

water as long as it is available and of acceptable quality. 

4.3.5 Adjusted M&I Demand 

Adding the effluent dilution requirement (1,100 to 1,600 acre-feet per year) and susceptible mine 

tunnel volume (2,000 acre-feet per year) to the total demand projected with conservation as 

shown previously in Table 4-3 yields an adjusted total M&I demand for the study area as shown 

in Table 4-4. For purposes of this study, the 2030 demand of 23,000 acre-feet per year (with 

conservation) and 2050 demand of 27,000 acre-feet per year (with conservation) are the demands 

that will need to be met by a combination of the projected reliable supplies discussed below and 

the water supply development options presented in Chapter 5. 
Park City and Snyderville Basin Water Supply Study Special Report 

4-7 

4.4 Projected Reliable Supplies 

There are a number of water supply resources in the study area which were not included in the 

existing supplies discussed in Chapter 2 but which, for purposes of this report, are assumed to be 

available supplies for 2030 and 2050. These include the Lost Creek Canyon Pipeline Project, the 

Jordanelle Special Service District import, additional groundwater supplies, and agricultural 

water conversions. Also, the need for continued system surplus/reserve will continue into the 

future. Following is a discussion of each, including the amount by which they are expected to 

affect future available supplies. It is important to note that this study assumes that these water 

supply resources are developed concurrently with the growing population and are utilized to 

become part of the projected reliable supplies. 

4.4.1 Lost Creek Canyon Pipeline 

The Lost Creek Canyon Pipeline Project was completed and dedicated in October 2004. The 

current capacity of this project is 1,600 acre-feet per year. The source water comes from shallow 

wells near the Weber River above Rockport Reservoir. The existing infrastructure included in 

this importation project consists of the following: a shallow groundwater well system on the 

Weber River; a booster pump station; approximately 27,000 linear feet of 24-inch water 

transmission line to convey water from the well system to the Signal Hill Water Treatment Plant; 

a 3 MGD (2,080 gpm), expandable to 6 MGD (4,200 gpm), membrane water treatment plant 

located on the ridgeline above Three Mile Canyon; and two open reservoirs totaling 

approximately 15 acre-feet of raw water storage (Aqua Engineering, 2003). Current agreements 

contemplate that the pipeline may potentially convey up to 6,600 acre-feet per year to the 

Snyderville Basin. Although an expansion of the water importation capability of this system is 

presented as a potential water supply system component in Chapter 5, for purposes of 

TABLE 4-4 

Adjusted M&I Demands

Population or 

Volume (acre-feet) 

2030* 2050* 

Population 64,300 86,300 

Calculated M&I Demand 25,300 32,000 

Water Conservation (2,300) (5,000) 

Net M&I Demand 23,000 27,000 

Minimum Instream Flow / Effluent 

Dilution Requirement 1,100 1,600 

Susceptible Mine Tunnel Flows 2,000 2,000 

Adjusted M&I Demand 26,100 30,600 

* Rounded to nearest 100 acre-feet.
Park City and Snyderville Basin Water Supply Study Special Report 

4-8 

determining projected future needs, this infrastructure is assumed to contribute 1,600 acre-feet 

per year to the reliable supplies for 2030 and 2050. 

4.4.2 Jordanelle Special Service District Import 

Park City currently receives water from Jordanelle Special Service District (JSSD) under a 20-

year lease. This water comes from the Ontario Drain Tunnel. The current delivered flow 

capacity is approximately 1.4 MGD (1,000 gpm) and up to 1,000 acre-feet per year. The 

facilities for this delivery have already been constructed and are in operation. They consist of a 

filtration water treatment plant located at the mouth of the Ontario Drain Tunnel on the 

northwest side of Jordanelle Reservoir and approximately 15,400 linear feet of 12-inch treated 

water transmission pipeline. Even though the 1,000 acre-feet per year delivery contract expires 

in 2022, both Park City and JSSD expect deliveries will continue in perpetuity. 

4.4.3 Additional Groundwater Development 

In its study of the Basin, the Utah Geological Survey (UGS) found the groundwater system in the 

Snyderville Basin to be highly compartmentalized. Pumping of groundwater in one 

compartment does not appear to directly affect groundwater levels in other compartments. While 

it is possible that the majority of the best groundwater sources have already been developed by 

the existing water suppliers in the Basin, it is still very likely that additional groundwater 

development will occur. While the three largest water suppliers in the area (Park City, Mountain 

Regional Special Service District, and Summit Water Distribution Company), do not intend to 

develop any substantial amount of additional groundwater, other smaller entities and individuals 

with approved groundwater rights will likely continue to develop small quantities of 

groundwater. For purposes of the projected needs calculations in this chapter, it is assumed that 

these groundwater developments will add 200 acre-feet per year to the 2030 reliable supplies and 

300 acre-feet per year to the 2050 reliable supplies. 

4.4.4 Agricultural Water Conversions 

As with other urbanizing areas of the state, lands historically used for agriculture in the 

Snyderville Basin are being developed into homes and businesses. Based on the State 

Engineer’s calculations of depletion, a portion of the water once used on irrigated lands becomes 

available to meet the needs of the new M&I uses. The depletion allowed for the new use can be 

no greater than the depletion allowed for the agricultural use, and there may be limitations on the 

new use if there would be adverse effects to other water right holders in the area. 

UDWR inventories water related land use for the entire state on a rotating basis. In 2003, 

surface irrigated acreage within the study area was estimated to be 1,100 acres. At the current 

development rate, and realizing that some of the lands are currently protected under conservation 

easements as open space and others will likely be protected, it is estimated that in 2050 the 

irrigated acreage will decline to less than a few hundred acres. 

By 2050, UDWR estimates that 300 acres of irrigated lands have associated water rights that 

could be converted. The water associated with these lands that should become available for M&I 

uses would be between 400 and 500 acre-feet per year. For purposes of the projected needs 

calculations in this chapter, it is assumed that these conversions will add 400 acre-feet per year to 

the 2030 reliable supplies and 500 acre-feet to the 2050 reliable supplies. 
Park City and Snyderville Basin Water Supply Study Special Report 

4-9 

4.4.5 System Surplus/Reserve Capacity Needs 

As discussed in Chapter 2, the actual reliable water supply within the Snyderville Basin may be 

somewhat lower than the estimate of 14,000 acre-feet per year of available supply (see Table 2-4 

and Section 2.4.2). Subtracting the actual 2001 use of 9,800 (rounded) acre-feet from 14,000 

acre-feet leaves a difference of 4,200 acre-feet per year. There are a number of factors which 

currently prevent the use of much of this surplus supply. One of the major limiting factors is that 

each system is operated independently from the others. When one system is experiencing its 

peak demand, it cannot be met using another system’s resources. There are some 

interconnections between water systems to provide this capability, but they are not widespread. 

The history of competition among water providers in the Snyderville Basin has also limited the 

amount of cooperation achievable to meet each other’s needs. In addition to these concerns, 

much of this surplus or reserve capacity, does not correspond to peak demand times, and without 

additional surface storage in the Basin, is not available when needed. 

Furthermore, local water suppliers and prudent water planning standards stress the importance of 

providing a sufficient amount of reserve capacity to prevent shortages during emergencies, when 

some water sources may not be available. As a result, for purposes of this study, this surplus or 

reserve capacity of 4,200 acre-feet per year has been subtracted from projected reliable supplies. 

This volume of water needed for reserve capacity is expected to increase in the future as the 

M&I demand grows and greater stress is placed on existing water systems. The ability to share 

water supplies among water providers is also expected to improve, as more interconnects are 

constructed and the area becomes more densely populated bringing systems closer together. For 

purposes of this study, the projected percentages of total available supplies needed for reserve 

capacity will reduce from the current 30 percent to 20 percent for years 2030 and 2050. This 

reserve capacity is therefore computed to be 6,500 acre-feet in the year 2030 and 7,500 acre-feet 

in 2050. Table 4-5 summarizes the projected reliable supplies as discussed in this section and as 

used for the calculation of projected needs. 

4.5 Projected Future Needs 

In order to calculate the projected future additional M&I water needs within the Snyderville 

Basin, the projected reliable supplies are subtracted from the adjusted M&I demands as shown in 

Table 4-5. As shown from this calculation, an additional water supply of approximately 15,400 

acre-feet will be needed in 2030 and 20,700 acre-feet will be needed in 2050. These numbers 

represent the future supply deficits that need to be satisfied by the various water supply options 

presented in Chapter 5. 
Park City and Snyderville Basin Water Supply Study Special Report 

4-10 

TABLE 4-5 

Projected M&I Needs

Volume (acre-feet) 

2001 2030 2050

Adjusted M&I Demand 9,800 23,000 27,000

In-stream Flow & Dilution Req. 0 1,100 1,600

Mine tunnel replacement water 0 2,000 2,000

Projected M&I Demand 9,800 26,100 30,600

Existing Supplies* 14,000 14,000 14,000

Lost Creek Canyon Pipeline Project 0 1,600 1,600

Jordanelle Special Service District 

Import 

0 1,000 1,000

Additional Groundwater 0 200 300

Agricultural Conversions 0 400 500

Reserve Capacity (4,200) (6,500) (7,500)

Projected Reliable Supply 9,800 10,700 9,900

Projected Additional M&I Needs** 0 15,400 20,700

* Available supply from Chapter 2 (rounded to nearest 100 acre-feet). 

** Projected M&I Demand minus Projected Reliable Supply.