U.S. Department of the Interior

U.S. Geological Survey

Open-File Report 2020–1106

Water Availability and Use Science Program

Prepared in cooperation with the Utah Department of Natural Resources

Development of a Method to Identify Complex Wells and 

Assess the Accuracy of Basin Withdrawals in Utah
Cover Photo: Photograph of Goshen Valley looking north-northeast toward Mount Timpanogos. 

Photograph by Christopher Wilkowske, U.S. Geological Survey, March 22, 2004.
Development of a Method to Identify 

Complex Wells and Assess the Accuracy 

of Basin Withdrawals in Utah

By Brittany L. Gold, Cory E. Angeroth, and Thomas M. Marston

Water Availability and Use Science Program

Prepared in cooperation with the Utah Department of Natural Resources

Open-File Report 2020–1106

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

DAVID BERNHARDT, Secretary

U.S. Geological Survey

James F. Reilly II, Director

U.S. Geological Survey, Reston, Virginia: 2020

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Suggested citation:

Gold, B.L., Angeroth, C.E., and Marston, T.M., 2020, Development of a method to identify complex wells and 

assess the accuracy of basin withdrawals in Utah: U.S. Geological Survey Open-File Report 2020–1106, 23 p., 

https://doi.org/10.3133/ofr20201106.

Associated data for this publication:

Gold, B.L., 2020, Historical power consumption coefficients and 2016 power usage for irrigation wells in Tooele, 

Parowan, and Goshen Valley, Utah: U.S. Geological Survey data release, https://doi.org/10.5066/P92UVVV6.

ISSN 2331-1258 (online)
iii

Acknowledgments

The authors would like to thank James Greer of the Utah Department of Natural Resources, 

Division of Water Rights for his cooperation and partnership during all phases of the study. 

The authors also thank the technicians of the Utah Water Science Center who, over the last 

50 years, spent countless hours measuring and recording power consumption coefficients across 

the state. Without their hard work and dedication, this analysis would not have been possible.

v

Contents

Acknowledgments........................................................................................................................................iii

Abstract...........................................................................................................................................................1

Introduction.....................................................................................................................................................1

Purpose and Scope .......................................................................................................................................2

Methods...........................................................................................................................................................4

Power Consumption Coefficient and Groundwater Withdrawal ..................................................4

Well Classification ................................................................................................................................4

Field Verification of Wells ...........................................................................................................9

Statistical Outliers .......................................................................................................................9

Groundwater Withdrawal .........................................................................................................11

Findings..........................................................................................................................................................12

Tooele Valley........................................................................................................................................14

Parowan Valley ...................................................................................................................................14

Goshen Valley ......................................................................................................................................14

Calculated Versus Directly Measured Withdrawal in Goshen Valley........................................16

Summary........................................................................................................................................................20

References Cited..........................................................................................................................................23

Figures

1. Map showing location of Tooele, Parowan, and Goshen groundwater 

basins in Utah ................................................................................................................................3

2. Map showing active irrigation wells in Tooele Valley, Utah ..................................................5

3. Map showing active irrigation wells in Parowan Valley, Utah .............................................6

4. Map showing active irrigation wells in Goshen Valley, Utah ................................................7

5. Graphs showing historical power consumption coefficients for two active 

irrigation wells in Tooele Valley, Utah .......................................................................................8

6. Graphs showing historical power consumption coefficients for two wells in 

Tooele Valley, Utah .....................................................................................................................10

7. Graph showing comparison of season-long power consumption coefficient 

(PCC) calculated from dedicated flowmeters and the instantaneous measured 

PCC from the most recently measured PCCs in Goshen Valley, Utah, using 20 

wells with dedicated flowmeters, 2016 power consumption, and historical PCCs .........19

8. Graph showing percent difference between dedicated flowmeter withdrawal 

and withdrawal calculated using other methods in Goshen Valley, Utah, 2016 ..............20

9. Graphs showing estimated annual groundwater withdrawal calculated 

using historical minimum power consumption coefficients (PCCs), historical 

maximum PCCs, historical mean PCCs, valley average PCCs, and the most 

recently measured PCCs and normalized percent difference between annual 

groundwater withdrawal calculated using historical mean PCCs and annual 

groundwater withdrawal calculated using other methods in 2016 for Tooele, 

Parowan, and Goshen Valleys, Utah .......................................................................................21

10. Graphs showing wells classified as simple, complex, and borderline in each 

basin, Tooele, Parowan, and Goshen, Utah, 2016..................................................................22
vi

Tables

1. Coefficient of variation thresholds for classification of irrigation wells based on 

historical PCCs ..............................................................................................................................8

2. Irrigation well classification by basin in Utah, 2016................................................................9

3. Irrigation wells with minor statistical outliers in each test basin: Tooele, 

Parowan, and Goshen, Utah, and the number of wells that changed 

classification upon removal of outlier power consumption coefficient(s), 2016 .............10

4. Historical power consumption coefficient measurements for two wells in 

Tooele Valley, Utah, 2016 ...........................................................................................................10

5. Annual groundwater withdrawal from active irrigation wells in Tooele, 

Parowan, and Goshen Valleys, Utah calculated with and without power 

consumption coefficient outliers, 2016 ...................................................................................11

6. Calculated groundwater withdrawal using the most recent power consumption 

coefficients, historical minimum PCCs, and historical maximum PCCs, in Tooele 

and Parowan Valleys, Utah, 2016 .............................................................................................12

7. Method definitions for calculating annual groundwater withdrawal and 

calculated groundwater withdrawal in Utah, 2016 ...............................................................13

8. Percent difference between estimated annual groundwater withdrawal 

calculated using various combinations of historical power consumption 

coefficients from irrigation wells in Tooele Valley, Utah, 2016 ............................................14

9. Percent difference between estimated annual groundwater withdrawal 

calculated using various combinations of historical power consumption 

coefficients from irrigation wells in Parowan Valley, Utah, 2016 .......................................15

10. Percent difference between estimated annual groundwater withdrawal 

calculated using various combinations of historical power consumption 

coefficients from irrigation wells in Goshen Valley, Utah, 2016 ..........................................15

11. Percent difference between estimated annual groundwater withdrawal 

calculated using various combinations of historical power consumption 

coefficients from irrigation wells that have historical power consumption 

coefficients in Goshen Valley, Utah, 2016 ...............................................................................16

12. Percent difference between estimated annual groundwater withdrawal 

calculated using various combinations of historical power consumption 

coefficients from irrigation wells that have historical power consumption 

coefficients, 2016 power usage, and dedicated flowmeters in Goshen Valley, 

Utah, 2016.....................................................................................................................................17

13. Percent difference between estimated annual groundwater withdrawal 

calculated using various combinations of historical power consumption 

coefficients from complex irrigation wells that have historical power 

consumption coefficients, 2016 power usage, and dedicated flowmeters in 

Goshen Valley, Utah, 2016 .........................................................................................................17

14. Percent difference between estimated annual groundwater withdrawal 

calculated using various combinations of historical power consumption 

coefficients from simple irrigation wells that have historical power 

consumption coefficients, 2016 power usage, and dedicated flowmeters in 

Goshen Valley, Utah, 2016 .........................................................................................................18
vii

15. Percent difference between estimated annual groundwater withdrawal 

calculated using various combinations of historical power consumption 

coefficients from borderline irrigation wells and wells with three or fewer 

historical power consumption coefficients that have historical power 

consumption coefficients, 2016 power usage, and dedicated flowmeters in 

Goshen Valley, Utah, 2016 .........................................................................................................18

Conversion Factors

U.S. customary units to International System of Units

Multiply By To obtain

Volume

acre-foot (acre-ft) 1,233 cubic meter (m3)

acre-foot (acre-ft) 0.001233 cubic hectometer (hm3)

 Flow rate

acre-foot per day (acre-ft/d) 0.01427 cubic meter per second (m3/s)

acre-foot per year (acre-ft/yr) 1,233 cubic meter per year (m3/yr)

acre-foot per year (acre-ft/yr) 0.001233 cubic hectometer per year (hm3/yr)

Abbreviations

CV coefficient of variation

DWRi Division of Water Rights

GW groundwater

PCC power consumption coefficient

TFM totalizing flowmeter

USGS U.S. Geological Survey

Development of a Method to Identify Complex Wells and 

Assess the Accuracy of Basin Withdrawals in Utah

By Brittany L. Gold, Cory E. Angeroth, and Thomas M. Marston

Abstract

Power consumption coefficients (PCCs) and dedicated 

flowmeter records for irrigation wells in three Utah 

groundwater basins were analyzed to develop a method 

to better characterize the accuracy of annual groundwater 

withdrawal estimates. The PCC method has been used by 

the U.S. Geological Survey in Utah since 1963 as a way 

to estimate groundwater withdrawal. As a result, most 

irrigation wells in Utah have historic records consisting 

of multiple PCCs. Over time, numerous wells have been 

retrofitted with dedicated flowmeters to more accurately 

describe groundwater use for irrigation. The combination of 

historical PCCs and flowmeter data was examined to classify 

wells as simple, complex, or borderline. The PCCs for each 

well were statistically analyzed for each period of record to 

determine the PCC coefficient of variation (CV). Variance, 

standard deviation, and CV also were calculated for each 

well, yielding similar results. The CV was selected as the 

best statistical method for classifying wells. Through field 

verification and examination of records, CV thresholds were 

established, allowing wells to be classified as simple, complex, 

or borderline. This well classification provides information 

on the uncertainty and best methods for quantifying annual 

groundwater withdrawals from irrigation wells in a basin.

Annual irrigation groundwater withdrawals in Tooele, 

Parowan, and Goshen Valleys were calculated by using 

various combinations of historical PCC records and data 

from dedicated flowmeters. Differences between annual 

groundwater withdrawal using the most recent measurements, 

and historic minimum, maximum, mean, and median PCCs 

were compared. The smallest percent difference between 

annual groundwater withdrawal calculated using the most 

recently measured PCCs, which is the current method for 

calculating withdrawal in most basins, in Tooele and Parowan 

Valleys, was 7 and 9 percent respectively, using historical 

median and mean.

In Goshen Valley, most wells have dedicated flowmeters, 

and there is a subset of wells that have 2016 power usage 

data, historical PCC records, and 2016 reported dedicated 

flowmeter withdrawal. Using this subset of irrigation wells, 

the smallest percent different between withdrawal from 

dedicated flowmeters and withdrawal calculated by using 

other methods was 5 percent (using withdrawal calculated 

with historical mean PCCs for each well). Annual groundwater 

withdrawal calculated using the most recently measured 

PCCs was 9-percent less than dedicated flowmeter reported 

withdrawal. So, if withdrawal from dedicated flowmeters is as 

close to reality as possible, then in the case of Goshen Valley, 

using historical mean PCCs to calculate withdrawal is closer 

to reality than using the most recently measured PCCs to 

calculate withdrawal.

Introduction

Accurate determination of water use, particularly 

groundwater use, is a critical component of assessing 

water availability in the arid western United States. A large 

component of total water use is groundwater withdrawal for 

irrigation. Since 1963, the U.S. Geological Survey (USGS) 

Utah Water Science Center, in cooperation with the Utah 

Department of Natural Resources Division of Water Rights 

(DWRi), has estimated annual groundwater withdrawal from 

basins in Utah.

Over time, irrigation systems have changed from surface 

water ditch diversions to simple groundwater-based sprinkler 

systems to wheel lines and center pivot sprinklers to more 

complex integrated systems with multiple wells and variable 

speed pumps that supply one or more systems. A “complex 

system” is defined by the Colorado District Court, Water 

Division No. 2 as “any system where the total dynamic head 

at the pump will vary due to multiple discharge locations in a 

pipeline, or where the method of delivery will vary between 

open discharge, gated pipe, or sprinkler system during a 

single irrigation season, or where multiple wells discharge 

into a common pipeline” (Colorado Department of Natural 

Resources Division of Water Resources, unpub. data, 2008).
2 Development of a Method to Identify Complex Wells and Assess the Accuracy of Basin Withdrawals in Utah

One aspect needed to better quantify annual groundwater 

withdrawals is understanding the role of complex well 

systems. Understanding the role of complex well systems 

includes a thorough assessment of the number of complex 

well systems, information about wells that have changed from 

simple to complex configurations, and an evaluation of the 

effect the overall accuracy of discrete measurements taken 

from complex well systems has on estimates of groundwater 

withdrawal. The effects of well configuration, conversion 

from simple to complex wells, and the presence or absence 

of dedicated flowmeters on withdrawal estimates made in 

the Tooele, Parowan, and Goshen groundwater basins are 

assessed in this report (fig. 1). Withdrawal estimates for these 

basins were made by evaluating power consumption records 

for individual wells. The assessment will allow the DWRi to 

consider options for improving irrigation withdrawal estimates 

in the future.

The power consumption coefficient (PCC) method 

has been used by the USGS in Utah since 1963 as a way to 

estimate groundwater withdrawal. The power consumption 

coefficient is determined by measuring the amount of electrical 

energy required to pump a known volume of water. Following 

the irrigation season, the total amount of electricity used by 

the pump is multiplied by the PCC to estimate the volume 

of water withdrawn that season from a given well. Annual 

groundwater withdrawal from most irrigation basins in Utah 

is currently calculated using the most recently measured PCC 

record for each well, except in Parowan and Goshen Valleys. 

In Parowan Valley, the average of each well’s most recently 

measured PCC is used to develop a valley average, which 

is then applied to all wells. In Goshen Valley, flowmeters 

are permanently installed on some wells, and a combination 

of measured withdrawals from permanent flowmeters and 

calculated withdrawals using the most recently measured 

PCC are used. For the purpose of this report, permanently 

installed flowmeters are referred to as dedicated flowmeters. 

Historically, wells were revisited every 1–3 years to update 

the PCC. The PCCs were last measured in Tooele Valley in 

2017; Parowan Valley in 2013; and Goshen Valley in 2014. 

The frequency of visits helped to improve accuracy because 

the PCC can change over time for a variety of reasons, such as 

change in depth to water, change in irrigation practice, pump 

wear, or system configuration.

Large variability in the PCC for individual wells could 

indicate that the well is part of a complex irrigation system 

and can be used as a screening tool to identify complex wells. 

Complex wells increase the uncertainty of groundwater 

withdrawal estimates. Uncertainty regarding basin-wide 

withdrawal estimates is likely to increase with the growing 

numbers of complex wells.

Purpose and Scope

The purpose of this study is to assess the effectiveness 

and accuracy of annual groundwater withdrawal estimates in 

Utah and the impact of dedicated flowmeters and complex 

wells on withdrawal estimates. Specifically, this study assesses 

the percent difference among annual groundwater withdrawal 

from irrigation wells calculated using different combinations 

of PCCs. The study also tests a statistical screening method by 

using existing PCCs to identify simple and complex wells and 

the effects of complex wells in three test basins.

The classification of wells as simple or complex is based 

on variability in historical PCCs and compose the first part of 

this study. The second part of this study evaluates the effects of 

complex wells on basin-wide estimates of annual withdrawal. 

After complex wells have been identified, the annual 

withdrawal estimates for each well are recalculated using the 

historical maximum and minimum PCCs. The basin-wide 

annual withdrawal calculated by using historical maximum 

and minimum PCCs represents the range of estimated 

groundwater withdrawal and can be used to bracket and 

assess the impacts of complex wells on the annual basin-wide 

withdrawal estimates. Specific components of this analysis 

include computing the annual estimated withdrawal for the 

three basins based on historical PCCs using the (1) most 

recently measured PCC for all wells, (2) minimum PCC for 

all wells, (3) maximum PCC for all wells, (4) mean PCC for 

all wells, (5) median PCC for all wells, (6) maximum PCC for 

complex wells and most recently measured PCC for simple 

and borderline wells, (7) maximum PCC for complex and 

borderline wells and most recently measured PCC for simple 

wells, (8) minimum PCC for complex wells and most recently 

measured PCC for simple and borderline wells, (9) minimum 

PCC for complex and borderline wells and most recently 

measured PCCs for simple wells, and (10) valley average 

PCCs. Additional elements in this analysis include assessing 

the percent difference between the measured PCC estimated 

annual withdrawal and the estimated annual withdrawal using 

various combinations of PCCs to calculate withdrawal. This 

analysis also includes assessing sources of variability of PCCs 

and estimated withdrawals to evaluate the accuracy of historic 

estimates and establish a method for improved data collection.
Purpose and Scope 3

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Tooele Valley

Goshen Valley

Parowan Valley

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EXPLANATION

Study groundwater basins

County boundaries

Figure 1. Location of Tooele, Parowan, and Goshen groundwater basins in Utah.
4 Development of a Method to Identify Complex Wells and Assess the Accuracy of Basin Withdrawals in Utah

Methods

Groundwater withdrawal estimates in Utah have largely 

been computed using PCCs. Statistical analyses of the changes 

in a well’s PCC can be used to classify wells as simple, 

complex, or borderline. Historical PCC records also are used 

to better understand estimation errors and best methods for 

determining agricultural water use.

Power Consumption Coefficient and 

Groundwater Withdrawal

The PCC is determined by measuring the amount of 

electrical power used to pump a volumetric rate of water 

(gallons per minute) from the ground to the crop. Annual 

groundwater withdrawal can then be estimated by multiplying 

the PCC by the annual electric energy usage of the well. The 

PCC method for estimating groundwater withdrawal has been 

directly compared (Dash and others, 1999) to groundwater 

withdrawal measured with totalizing flowmeters (TFM). 

Values of groundwater withdrawal from direct measurements 

with TFM and estimates from PCC compare favorably except 

when a well is part of a complex system. When a well is 

part of a complex system, the two methods typically yield 

different results.

Estimates of groundwater withdrawal from irrigation 

wells in Utah are computed using the PCC method (Hurr and 

Litke, 1989), which has changed little during the last 50 years. 

The PCC method requires a site visit to the well to determine 

the amount of electric power (kilowatts) required to pump a 

volumetric rate of water out of the ground and transport it to 

the crop. Electric power meters, at the wellhead, measure the 

electric power that passes through the meter by the revolution 

of a dial on an analog meter or digital bar on a digital 

meter. The quantity of electric power is calculated from the 

following equation:

 a = r*3.6*k (1)

where

a is the electric power demand, in kilowatts;

r is the measured average time of meter cycle, 

in cycles per second;

3.6 is a conversion factor in kilowatt-seconds per 

watt-hour; and

k is watt-hours per cycle (imprinted on the front 

of power meter).

Once electric power is quantified, the resulting discharge 

rate (volume per time) of water pumped by the electric 

power is determined. Discharge rate is measured by using a 

temporary flowmeter fitted to the well plumbing during a field 

visit (Marston, 2017). Flowmeters measure water velocity 

(length per time), which is multiplied by the cross-sectional 

area of the pipe to determine the groundwater discharge rate 

(volume per time). Electric power (kilowatts) and discharge 

are converted to a PCC using the equation:

 PCC = (w*0.1841)/ a (2)

where

PCC is the measured power consumption 

coefficient, in acre-feet per 

1,000 kilowatt-hours;

w is instantaneous groundwater discharge, in 

gallons per minute;

a is the electric power demand, in 

kilowatts; and

0.1841 is a conversion factor, (1 acre-feet * 

60 minute * 1,000) per (325,851 gallons * 

1 hour * 1,000 kilowatts).

Well Classification

Method development and testing was done on wells 

in the following groundwater basins: Tooele, Parowan, and 

Goshen Valleys (figs. 2, 3, and 4). For each basin, data from 

field books that contained PCC computations in paper form 

were converted to an electronic format, which allowed for data 

analysis and organization. The PCC’s for Tooele, Parowan, 

and Goshen Valleys are available in a USGS data release 

(Gold, 2020). The PCC’s were only established for wells 

operating during the site visit. The PCCs for each well were 

statistically analyzed for each period of record to determine 

the PCC coefficient of variation (CV) and evaluate statistical 

outliers in the dataset for each well. Variance, standard 

deviation, and CV were calculated for each well and yielded 

similar results. The CV was selected as the best statistical 

method for classifying wells as simple or complex because of 

its ability to compare datasets to each other regardless of the 

magnitude of values in each dataset (Reed and others, 2002).

Field verification of select wells with variability in 

historical PCC records was done for wells in Tooele Valley. 

Field verification consisted of inspecting the wells for multiple 

pipes, controls, and pivots that would indicate a complex 

well configuration. Wells were visited to verify they had been 

correctly classified using CV.

For wells with more than three historical PCC records, 

statistical outliers were calculated for each well’s PCC using 

the interquartile range to evaluate the effect of outliers on 

basin-wide groundwater withdrawal (Zwillinger and Kokoska, 

2000). The CV for each of these wells was then reevaluated 

after removing statistical outliers from the dataset.
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Background image is the intellectual property of Esri and is used herein under license. Copyright © 2020 Esri and its licensors. All rights reserved. EXPLANATION

Tooele Valley

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Studyarea

SALT LAKE COUNTY

TOOELE COUNTY

Figure 2. Active irrigation wells in Tooele Valley, Utah.
6 Development of a Method to Identify Complex Wells and Assess the Accuracy of Basin Withdrawals in Utah

Background image is the intellectual property of 

Esri and is used herein under license. Copyright © 

2020 Esri and its licensors. All rights reserved. 

EXPLANATION

Parowan Valley

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Figure 3. Active irrigation wells in Parowan Valley, Utah.
Methods 7

JUAB COUNTY

UTAH COUNTY

112°5' 111°55' 111°45'

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Background image is the intellectual property 

of Esri and is used herein under license. 

Copyright © 2020 Esri and its licensors. All 

rights reserved. 

EXPLANATION

Goshen Valley

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Figure 4. Active irrigation wells in Goshen Valley, Utah.
8 Development of a Method to Identify Complex Wells and Assess the Accuracy of Basin Withdrawals in Utah

Through field verification and examination of records, 

the following thresholds were established. If the CV for a well 

is less than 0.2, the well is classified as simple. If the CV is 

greater than 0.25, the well is classified as complex. A third 

group consisting of borderline wells also was established. 

If the CV for a well is between these two values or the well 

has three or fewer historical PCCs, the well is classified as 

borderline (table 1). Historical PCC records for two wells 

in Tooele Valley indicated that the range of PCC values for 

well (C-2-4)28dab-1 (classified as complex) was greater than 

the range for well (C-3-6)1bdb (classified as simple) and the 

CV was higher for the complex well than for the simple well 

(fig. 5).

In each test basin, active irrigation wells (as of 2016) 

were classified based on the CV of their historical PCCs. In 

Tooele Valley, there were 46 active irrigation wells (none of 

which had dedicated flowmeters): 23 wells were classified 

as complex, 7 wells were classified as simple, 1 well was 

classified as borderline, and 15 wells had 3 or fewer historical 

records and were not classified. In Parowan Valley, there 

were 115 active irrigation wells (none of which had dedicated 

flowmeters): 5 wells were classified as complex, 47 wells 

were classified as simple, 7 wells were classified as borderline, 

and 17 wells had 3 or fewer historical records and were not 

classified. There were 39 active irrigation wells in Parowan 

Valley that did not have historical PCC records. These wells 

have historically been assigned the Parowan Valley valley 

average PCC from the most recent PCC ratings. In Goshen 

Valley, there were 30 active irrigation wells, of which 24 had 

dedicated flowmeters; 8 wells were classified as complex, 

4 wells were classified as simple, 5 wells were classified as 

borderline, and 13 wells had 3 or fewer historical PCC records 

and were not classified. Twenty of the active irrigation wells in 

Goshen Valley have dedicated flowmeters, 2016 power-usage 

data, and historical PCCs; four wells have dedicated 

flowmeters, but the 2016 power use data was not reported; six 

wells do not have dedicated flowmeters; these six wells only 

have 2016 power use and historical PCCs (table 2).

Table 1. Coefficient of variation thresholds for classification 

of irrigation wells based on historical power consumption 

coefficients (PCCs) .

[<, less than; >, greater than, ≤, less than or equal to]

Classification

Simple Complex Borderline or ≤ three 

historical PCCs

<0.2 >0.25 0.20–0.25

0

1

2

3

4

5

6

7

8

9

10

Power consumption coefficient (PCC), in acre-feet/1,000 kWh

CV = 0.41

CV = 0.12

1960 1970 1980 1990 2000 2010 2020

Year

EXPLANATION

(C-3-6)1bdb

(C-2-4)28dab-1

Figure 5. Historical power consumption coefficients (PCCs) for two active irrigation wells in Tooele 

Valley, Utah.
Methods 9

Table 2. Irrigation well classification by basin in Utah, 2016.

[≤, less than or equal to; PCC, Power consumption coefficient; —, no data]

Active 

irrigation 

wells

Meter type

Wells with 

dedicated 

flowmeters

Complex 

wells

Simple 

wells

Borderline 

wells

≤ Three 

historical 

measurements

Wells without 

PCC records

Tooele Valley, Utah

46

Dedicated flowmeter 0 — — — — —

No dedicated flowmeter 46 23 7 1 15 0

Parowan Valley, Utah

115

Dedicated flowmeter 0 — — — — —

No dedicated flowmeter 115 5 47 7 17 39

Goshen Valley, Utah

30

Dedicated flowmeter 24 8 4 4 8 0

No dedicated flowmeter 6 — — 1 5 0

Field Verification of Wells

Field verification of wells in Tooele Valley was done in 

June 2018 for 14 of the 46 active wells. Eleven wells were 

field verified as complex. Six of these wells were classified as 

complex based on CV and two fell within the borderline range. 

Three of the field verified complex wells had less than four 

historical PCCs and were not classified on the basis of CV. 

Two wells were field verified as simple, of which one well was 

classified as simple by using the CV method. Field verification 

supported the thresholds established for classification of wells 

as simple, complex, and borderline based on the CV of each 

well’s historical PCCs.

Statistical Outliers

The interquartile range was used to calculate minor 

statistical outliers for each well to determine if outliers 

affected classification, if outliers affected basin-wide annual 

groundwater withdrawal, and if outliers should be removed 

from or included in the dataset. To understand the effect of 

outliers, PCCs outside of the interquartile range for each 

well were identified as statistical outliers. The CV was 

reevaluated for each well with a PCC identified as a statistical 

outlier to understand if removal of outliers changed the 

well’s classification, for example, from complex to simple. 

Basin-wide annual groundwater withdrawal was calculated 

with the complete dataset including outliers and separately 

with outliers removed to determine if outliers influence 

basin-wide annual groundwater withdrawal. Removal of 

outliers had the largest impact on classifications of wells in 

Tooele Valley, which has more complex wells than Parowan or 

Goshen Valleys. The number of statistical outliers calculated 

for each test basin and how the removal of the outlier PCC(s) 

affected classification, is presented in table 3.

In Tooele Valley, 16 wells had 1 or more historical 

PCCs flagged as a statistical outlier. Removing outliers 

from the historical record and recalculating CV changed the 

classification of eight wells (table 3). With outliers removed, 

recalculated CV changed four well classifications from 

complex to simple; three wells changed classification from 

complex to borderline or had three or fewer PCCs; one well 

changed classification from borderline to simple; and eight 

wells classification did not change. Examples of two wells 

with PCCs flagged as outliers are presented in table 4 and 

figure 6. Well (C-2-4)3bcb-3 was classified as complex with 

all historical records used to calculate CV (CV=0.34). This 

well had three PCC records flagged as statistical outliers: 

6.5, 7.03, and 2.01 (fig. 6). Removing those values and 

recalculating the CV reclassified this well as simple (table 4; 

CV=0.11). Well (C-2-5)5ccd-1 was classified as borderline 

with all historical PCC records used to calculate CV (table 4; 

CV=0.22). This well had one PCC of 1.47 flagged as a 

statistical outlier. Removal of this outlier PCC changed 

the well’s classification from borderline to simple (table 4; 

CV=0.10).
10 Development of a Method to Identify Complex Wells and Assess the Accuracy of Basin Withdrawals in Utah

Table 3. Irrigation wells with minor statistical outliers in each test basin: Tooele, Parowan, and Goshen, 

Utah, and the number of wells that changed classification upon removal of outlier power consumption 

coefficient(s), 2016.

[≤, less than or equal to]

Classification change with outlier(s) removed

Statistical outliers

Tooele 

Valley

Parowan 

Valley

Goshen 

Valley

Classification change from complex to simple 4 0 1

Classification change from borderline to simple 1 1 1

Classification change from complex to borderline or ≤ three historical records 3 1 3

Classification change from simple to ≤ three historical records 0 1 0

Classification did not change 8 19 1

Total wells with statistical outlier(s) 16 22 6

Table 4. Historical power consumption coefficient measurements for two wells in Tooele Valley, Utah, 2016.

[PCC, power consumption coefficient; acre-ft, acre-foot; kWh, kilowatt-hours; CV, coefficient of variation; —, no data]

PCC in acre-ft/1,000 kWh

Year 1975 1977 1978 1979 1980 1981 1987 1988 1990 1993 1995 2000 2001 2005 2007 2017

CV 

including 

statistical 

outliers

CV 

excluding 

statistical 

outliers

1, 2(C-2-4)

33bcb-3 3.27 4.03 3.64 3.72 3.8 3.7 — 4.72 — — 4 — 6.5 — 7.03 2.01 0.34 0.11

1, 3(C-2-5)

5ccd-1 — — — — — — 2.97 2.49 2.39 2.79 — 1.47 — 3.11 — 2.95 0.22 0.10

1PCCs considered statistical outliers are highlighted.

2With outliers removed and CV recalculated, the classification of this well changes from complex to simple.

3With outliers removed and CV recalculated, the classification of this well changes from borderline to simple. Power consumption coefficient (PCC), in acre-feet/1,000 kWh

1960 1970 1980 1990 2000 2010 2020

Year

EXPLANATION

(C-2-5)5ccd-1

(C-2-4)33bcb-3

0

1

2

3

4

5

6

7

8

CV = 0.34

CV = 0.22

Figure 6. Historical power consumption coefficients (PCCs) for two wells in Tooele Valley, Utah.
Methods 11

In Parowan Valley, 22 wells had 1 or more historical 

PCCs flagged as statistical outliers. Removing outliers from 

the historical record and recalculating CV changed the 

classification of three wells (table 3). When the outlier(s) 

was removed, one well’s recalculated CV changed the well’s 

classification from borderline to simple, one well changed 

classification from complex to borderline, and one well was no 

longer classified because of three or fewer historical records.

In Goshen Valley, six wells had one or more historical 

PCCs flagged as a statistical outlier. Removing outliers 

from the historical record and recalculating CV changed the 

classification of five wells (table 3). When the outlier was 

removed, one well’s classification changed from complex to 

simple, one well’s classification changed from borderline to 

simple, three wells classifications changed from complex to 

borderline or three or fewer historical PCCs, and one well’s 

classification did not change.

Groundwater Withdrawal

All calculations of annual basin-wide groundwater 

withdrawal were completed with outliers included and 

excluded from each dataset. These calculations included using 

each well’s most recently measured, historical minimum, 

historical maximum, historical mean, historical median PCC, 

and valley average of the most recently measured PCCs 

to calculate basin-wide annual groundwater withdrawal. 

There was less than 5-percent difference between annual 

groundwater withdrawal calculated with and without statistical 

outliers, except in Tooele Valley where the difference was 

19 percent when the maximum historical PCC for each well 

was used to calculate withdrawal (table 5). Tooele Valley 

has the most complex well systems, and these complex well 

systems have the largest range of PCC values of the three 

test basins. Because of the nature of a complex well system 

and the lack of overall impact on withdrawal calculated 

with the exclusion of outliers, the outliers were included in 

withdrawal calculations.

Table 5. Annual groundwater withdrawal from active irrigation wells in Tooele, Parowan, and Goshen Valleys, Utah, 

calculated with and without power consumption coefficient (PCC) outliers, 2016.

[GW, groundwater; acre-ft, acre-foot; %, percent]

PCC used to calculate 

withdrawal

2016 Annual GW 

withdrawal (acre-ft) 

calculated with PCCs

2016 Annual GW 

withdrawal (acre-ft) 

calculated with PCC 

outliers removed

Difference between 

annual GW withdrawal 

(acre-ft) calculated with 

and without PCC outliers

Percent difference between 

annual GW withdrawal (%) 

calculated with and without 

PCC outliers

Tooele Valley

Most recent (measured) 5,394 5,449 –55 –1

Minimum 4,074 4,215 –141 –3

Maximum 8,587 7,190 1,397 19

Mean 5,962 5,678 284 5

Median 5,758 5,687 71 1

Valley average 5,693 5,727 –34 0

Parowan Valley

Most recent (measured) 36,642 37,111 –469 –1

Minimum 32,997 34,348 –1,351 –4

Maximum 46,693 45,304 1,389 3

Mean 39,795 39,832 –37 0

Median 39,937 39,942 –5 0

Valley average 37,079 37,503 –424 –1

Goshen Valley

Most recent (measured) 22,646 22,082 564 3

Minimum 22,433 21,869 564 3

Maximum 22,688 22,124 564 3

Mean 22,575 22,011 564 3

Median 22,576 22,012 564 3

Valley average 22,945 22,270 675 3
12 Development of a Method to Identify Complex Wells and Assess the Accuracy of Basin Withdrawals in Utah

As noted, CV was selected as the best statistical method 

for classifying wells as simple or complex because of its 

ability to compare datasets to each other regardless of the 

magnitude of values in each dataset (Reed and others, 2002). 

Field verification supports the classification threshold and the 

need for the borderline category. Visual inspection of the range 

of each well’s historical PCC records on scatter plots also 

support the classifications. In some cases, removal of outliers 

changes well classification; however, to minimize the amount 

of qualitative bias in the dataset, the outliers were included.

Findings

Annual groundwater withdrawal for 2016 was calculated 

for each test basin using a combination of each irrigation 

well’s historical PCCs, which included each irrigation well’s 

most recently measured PCC, historical minimum PCC, 

historical maximum PCC, historical mean PCC, historical 

median PCC, and a combination of PCC values based on 

well classification of simple, complex, or borderline. These 

different methods were used to calculate annual groundwater 

withdrawal to evaluate what, if any, impact different irrigation 

well configurations and different methods for calculating 

withdrawal have on the calculated basin-wide withdrawal.

Tooele and Parowan Valleys have the most complex and 

simple irrigation wells of the three test basins, respectively 

(table 2; figs. 10A, 10B). Eighty percent of active irrigation 

wells in Goshen Valley have dedicated flowmeters (fig. 10C); 

this basin will be discussed separately. When the minimum 

historical PCC for each irrigation well is used to calculate 

the annual groundwater withdrawal in Tooele Valley, the 

2016 annual groundwater withdrawal is 24-percent less than 

the withdrawal calculated using each irrigation well’s most 

recently measured PCC (table 6). Likewise, if the maximum 

historical PCC for each irrigation well is used, the 2016 

annual groundwater withdrawal is 59-percent greater than 

the most recently measured PCCs. When the minimum 

historical PCC for each irrigation well is used to calculate 

the annual groundwater withdrawal in Parowan Valley, the 

2016 withdrawal is 10-percent less than withdrawal calculated 

using each irrigation well’s most recently measured PCC 

(table 6). Likewise, if maximum historical PCC is used, the 

2016 withdrawal is 27-percent greater than the withdrawal 

calculated using the most recently measured PCCs (table 6). 

In Tooele Valley, with over 50 percent of its wells classified 

as complex, estimates of groundwater withdrawal could 

be overestimated or underestimated by 59 and 24 percent, 

respectively. In Parowan Valley, with over 40 percent of 

its wells classified as simple, estimates of groundwater 

withdrawal could be overestimated or underestimated by 

27 and 10 percent, respectively. From this analysis, larger 

CVs created by more complex wells result in a larger spread 

between minimum and maximum PCCs. Assuming that 

minimum-maximum is a measure of error, in basins with 

larger numbers of complex wells, the error associated with 

groundwater withdrawals is larger.

Table 6. Calculated groundwater withdrawal using the most recent power consumption coefficients (PCCs), historical 

minimum PCCs, and historical maximum PCCs in Tooele and Parowan Valleys, Utah, 2016.

[GW, groundwater; acre-ft, acre-foot; %, percent; —, no data]

PCC used to calculate 

withdrawal

2016 Annual 

GW withdrawal 

(acre-ft)

Difference in annual GW withdrawal 

(acre-ft) from withdrawal calculated 

with most recently measured PCC1

Percent difference in annual GW 

withdrawal (%) from withdrawal calculated 

with most recently measured PCC2

Tooele Valley

Most recent (measured) 5,394 — —

Minimum 4,074 –1,320 –24

Maximum 8,587 3,193 59

Parowan Valley

Most recent (measured) 36,642 — —

Minimum 32,997 –3,645 –10

Maximum 46,693 10,051 27

1The difference between using the most recent PCCs and the minimum or maximum PCCs.

2The percent difference between the most recent PCC and the minimum or maximum PCC.
Findings 13

Estimated annual groundwater withdrawals for each test 

basin were calculated using different PCC values. Method 

1 uses the most recently measured PCC for each well to 

estimate groundwater withdrawal. Methods 2 and 3 use 

the historical minimum PCC and the historical maximum 

PCC, respectively, for each well to estimate groundwater 

withdrawal. Methods 4 and 5 use the historical mean PCC and 

historical median PCC for each well to estimate groundwater 

withdrawal. Method 6 uses the historical maximum PCC for 

complex wells and the most recently measured PCC for simple 

and borderline wells to estimate groundwater withdrawal. 

Method 7 uses the historical maximum PCC for complex and 

borderline wells and the most recently measured PCC for 

simple wells to estimate groundwater withdrawal. Method 

8 uses the historical minimum PCC for complex wells and 

the most recently measured PCC for simple and borderline 

wells to estimate groundwater withdrawal. Method 9 uses 

the historical minimum PCC for complex and borderline 

wells and the most recently measured PCC for simple wells 

to estimate groundwater withdrawal. Method 10 uses the 

valley average of each well’s most recently measured PCC to 

estimate groundwater withdrawal. Method 11 uses measured 

withdrawal from dedicated flowmeters (note, there are no 

wells in Tooele or Parowan Valleys with dedicated flowmeters; 

24 wells in Goshen Valley have dedicated flowmeters; 

table 7). Historically, withdrawal in Tooele Valley has been 

calculated using the most recently measured PCC for each 

well (method 1, table 7); withdrawal in Parowan Valley has 

been calculated using the valley average PCC from all wells 

(method 10, table 7); withdrawal in Goshen Valley has been 

calculated using a combination of user-reported withdrawal 

from dedicated flowmeters and the most recently measured 

PCCs for those wells that do not have dedicated flowmeters 

(methods 11 and 1, respectively, table 7).

As noted, various methods were used to calculate annual 

groundwater withdrawal (table 7). Groundwater withdrawal 

estimated using the most recent PCC for each well (method 1, 

table 7) were compared to those calculated using other PCCs. 

Methods 6 through 10 (table 7) incorporate values calculated 

using method 1 and are therefore excluded from comparison in 

the following section because calculated annual groundwater 

withdrawal will be skewed toward those methods that include 

the most recently measured PCCs.

Table 7. Method definitions for calculating annual groundwater withdrawal and calculated groundwater withdrawal in Utah, 2016.

[PCC, power consumption coefficient; ≤, less than or equal to; —, no data]

Method 

number PCC record(s) used to calculate annual groundwater withdrawal

Estimated annual groundwater withdrawal 

by basin, in acre-foot

Tooele Valley, 

Utah

Parowan 

Valley, Utah

Goshen 

Valley, Utah1

Method 1 Most recent (measured) 5,394 36,642 22,646

Method 2 Historical minimum 4,074 32,997 22,433

Method 3 Historical maximum 8,587 46,693 22,688

Method 4 Historical mean 5,962 39,795 22,575

Method 5 Historical median 5,758 39,937 22,576

Method 6 Historical maximum complex, most recent (measured) simple and borderline/wells 

with ≤ three historical records 7,906 37,510 —

Method 7 Historical maximum complex and borderline/wells with ≤ three historical records, 

most recent (Measured) simple 8,557 41,283 —

Method 8 Historical minimum complex, most recent (measured) simple and borderline/wells 

with ≤ three historical records 4,444 35,827 —

Method 9 Historical minimum complex and borderline/wells with ≤ three records, most 

recent (measured) simple 4,347 34,530 —

Method 10 Valley average 5,693 37,079 22,945

Method 11 Flowmeter — — —

1Withdrawal estimated using dedicated flowmeter withdrawal when available and with method indicated for wells without dedicated flowmeters.
14 Development of a Method to Identify Complex Wells and Assess the Accuracy of Basin Withdrawals in Utah

Tooele Valley

In Tooele Valley, the smallest percent difference from 

withdrawal calculated using the most recently measured PCC 

for each irrigation well, method 1 (excluding methods that 

partially use most recent values), is withdrawal calculated 

using the historical mean, method 4, or historical median, 

method 5, PCCs for each irrigation well. Annual groundwater 

withdrawal calculated in 2016 using historical mean PCCs 

was 11-percent greater than withdrawal calculated with the 

most recently measured PCCs, and annual groundwater 

withdrawal calculated with historical median PCCs was 

7-percent greater than withdrawal calculated using the most 

recently measured PCCs (table 8). In Tooele Valley, annual 

groundwater withdrawal calculated with historical mean or 

historical median PCCs are close to withdrawal calculated 

with the most recently measured PCCs and reduce the need to 

rate wells as frequently.

Parowan Valley

In Parowan Valley, the smallest percent difference from 

withdrawal calculated using the most recently measured PCC 

for each irrigation well, method 1 (excluding methods that 

partially use most recent values), is withdrawal calculated 

using the historical mean, method 4, or historical median, 

method 5, PCCs from for each irrigation well in 2016. Annual 

groundwater withdrawal calculated in 2016 using historical 

mean and historical median was 9-percent greater than 

withdrawal calculated using the most recently measured PCCs 

(table 9). Because most of the wells in Parowan Valley are 

classified as simple, that is, their PCC does not vary much, 

using the valley average also is a good method for estimating 

annual groundwater withdrawal. However, this 1-percent 

difference between using the most recently measured PCCs 

and valley average PCCs to calculate withdrawal is skewed 

because the valley average is based on these records and may 

not represent actual withdrawal.

Goshen Valley

In Goshen Valley, withdrawal calculated using the most 

recently measured PCC for each irrigation well, method 1, 

compared to withdrawal calculated with using the historical 

minimum, method 2, historical maximum, method 3, historical 

mean, method 4, historical median, method 5, valley average, 

method 10, PCCs from for each irrigation wells in 2016 

was similar. Annual groundwater withdrawal calculated in 

2016 using each method is 2 percent or less than withdrawal 

calculated using the most recently measured PCCs (table 10). 

Because 80 percent of the wells in Goshen Valley have 

dedicated flowmeters, calculated groundwater withdrawal is 

similar regardless of the methods used to calculate withdrawal.

In 2016, Goshen Valley had 26 active irrigation wells that 

had power usage and historical PCCs. The smallest percent 

difference from withdrawal calculated using the most recently 

measured PCC for each irrigation well (excluding those 

partially calculated with the most recently measured values) 

is withdrawal calculated using historical mean, method 4, or 

historical median, method 5, PCCs from each irrigation well 

in 2016. Annual groundwater withdrawal calculated in 2016 

using historical mean and historical median was 14-percent 

greater than withdrawal calculated using the most recently 

measured PCCs (table 11). Although Goshen Valley has more 

complex than simple wells, annual groundwater withdrawal 

calculated using historical mean or historical median PCCs for 

active irrigation wells is close to withdrawal calculated using 

the most recently measured PCCs.

Table 8. Percent difference between estimated annual groundwater withdrawal calculated using various combinations 

of historical power consumption coefficients from irrigation wells in Tooele Valley, Utah, 2016.

[GW, groundwater; acre-ft, acre-foot]

Method 

number

Method 

1

Method 

2

Method 

3

Method 

4

Method 

5

Method 

6

Method 

7

Method 

8

Method 

9

Method 

10

Annual GW 

withdrawal 

(acre-ft)

Method 1 0 32 –37 –10 –6 –32 –37 21 24 –5 5,394

Method 2 –24 0 –53 –32 –29 –48 –52 –8 –6 –28 4,074

Method 3 59 111 0 44 49 9 0 93 98 51 8,587

Method 4 11 46 –31 0 4 –25 –30 34 37 5 5,962

Method 5 7 41 –33 –3 0 –27 –33 30 32 1 5,758

Method 6 47 94 –8 33 37 0 –8 78 82 39 7,906

Method 7 59 110 0 44 49 8 0 93 97 50 8,557

Method 8 –18 9 –48 –25 –23 –44 –48 0 2 –22 4,444

Method 9 –19 7 –49 –27 –25 –45 –49 –2 0 –24 4,347

Method 10 6 40 –34 –5 –1 –28 –33 28 31 0 5,693
Findings 15

Table 9. Percent difference between estimated annual groundwater withdrawal calculated using various combinations 

of historical power consumption coefficients from irrigation wells in Parowan Valley, Utah, 2016.

[GW, groundwater; acre-ft, acre-foot]

Method 

number

Method 

1

Method 

2

Method 

3

Method 

4

Method 

5

Method 

6

Method 

7

Method 

8

Method 

9

Method 

10

Annual GW 

withdrawal 

(acre-ft)

Method 1 0 11 –22 –8 –8 –2 –11 2 6 –1 36,642

Method 2 –10 0 –29 –17 –17 –12 –20 –8 –4 –11 32,997

Method 3 27 42 0 17 17 24 13 30 35 26 46,693

Method 4 9 21 –15 0 0 6 –4 11 15 7 39,795

Method 5 9 21 –14 0 0 6 –3 11 16 8 39,937

Method 6 2 14 –20 –6 –6 0 –9 5 9 1 37,510

Method 7 13 25 –12 4 3 10 0 15 20 11 41,283

Method 8 –2 9 –23 –10 –10 –4 –13 0 4 –3 35,827

Method 9 –6 5 –26 –13 –14 –8 –16 –4 0 –7 34,530

Method 10 1 12 –21 –7 –7 –1 –10 3 7 0 37,079

Table 10. Percent difference between estimated annual groundwater withdrawal 

calculated using various combinations of historical power consumption 

coefficients from irrigation wells in Goshen Valley, Utah1, 2016.

[GW, groundwater; acre-ft, acre-foot; PCC, power consumption coefficient]

Method 

number

Method 

1

Method 

2

Method 

3

Method 

4

Method 

5

Method 

10

Annual GW 

withdrawal 

(acre-ft)

Method 1 0 1 0 0 0 –1 22,646

Method 2 –1 0 –1 –1 –1 –2 22,433

Method 3 0 1 0 1 0 –1 22,688

Method 4 0 1 0 0 0 –2 22,575

Method 5 0 1 0 0 0 –2 22,576

Method 10 1 2 1 2 2 0 22,945

1For irrigation wells with dedicated flowmeters, user-reported withdrawal was used and for 

irrigation wells without dedicated flowmeters, PCCs were used to estimate withdrawal.
16 Development of a Method to Identify Complex Wells and Assess the Accuracy of Basin Withdrawals in Utah

Table 11. Percent difference between estimated annual groundwater withdrawal calculated using various 

combinations of historical power consumption coefficients (PCCs) from irrigation wells that have historical PCCs in 

Goshen Valley, Utah1, 2016.

[GW, groundwater; acre-ft, acre-foot]

Method 

number

Method 

1

Method 

2

Method 

3

Method 

4

Method 

5

Method 

6

Method 

7

Method 

8

Method 

9

Method 

10

Annual GW 

withdrawal 

(acre-ft)

Method 1 0 20 –32 –12 –12 –17 –29 6 19 –4 16,393

Method 2 –17 0 –43 –27 –27 –30 –41 –11 –1 –20 13,663

Method 3 46 75 0 29 28 22 4 55 74 40 23,964

Method 4 14 36 –22 0 0 –5 –19 21 35 9 18,617

Method 5 14 37 –22 0 0 –5 –19 21 36 9 18,676

Method 6 20 44 –18 5 5 0 –15 27 43 15 19,640

Method 7 40 68 –4 23 23 17 0 49 67 35 22,983

Method 8 –6 13 –36 –17 –17 –21 –33 0 12 –10 15,430

Method 9 –16 1 –43 –26 –26 –30 –40 –11 0 –19 13,770

Method 10 4 25 –29 –8 –9 –13 –26 11 24 0 17,069

1This table includes active irrigation wells in Goshen Valley that have historical PCCs and 2016 power usage. Power consumption 

coefficient calculated withdrawal is used for all wells included in these annual groundwater estimates. It excludes four active irrigation wells 

that have flowmeters and did not have 2016 power usage reported.

Calculated Versus Directly Measured 

Withdrawal in Goshen Valley

Goshen Valley had 20 wells with dedicated flowmeters, 

2016 power usage records, and historical PCCs. The smallest 

percent difference from withdrawal recorded by dedicated 

flowmeters, method 11, is withdrawal calculated using 

historical mean, method 4, or historical median, PCCs from 

each irrigation well in 2016. Annual groundwater withdrawal 

calculated in 2016 using historical mean and historical 

median was 5-percent greater than withdrawal reported 

by dedicated flowmeters (table 12). Annual groundwater 

withdrawal calculated in 2016 using the most recently 

measured, method 1, PCCs was 9-percent less than withdrawal 

reported by dedicated flowmeters, method 11 (table 12). 

Flowmeter reported withdrawal is more accurate than 

withdrawal calculated using PCCs (Marston, 2017). Annual 

groundwater withdrawal calculated using historical mean or 

historical median PCCs is closer to flowmeter withdrawal than 

withdrawal calculated using the most recently measured PCCs.

Because most of the wells in Goshen Valley are equipped 

with dedicated flowmeters, there is an opportunity to compare 

direct withdrawal measurements with each of the three 

categories of PCC-calculated withdrawal (complex, simple, 

and borderline) separately. For wells classified as complex, 

withdrawal calculated using method 1 (most recent), method 

4 (historical mean), and method 10 (Valley Average) were 

closest to dedicated flowmeter measurements (12-percent less, 

11-percent greater, and 11-percent less, respectively; table 13).

Calculated annual groundwater withdrawal for wells 

classified as simple yielded similar results. For simple 

wells, the smallest percent difference from withdrawal 

from dedicated flowmeters, method 11, is withdrawal 

calculated using the most recently measured, method 1, 

and valley average, method 10, PCCs from irrigation wells 

in 2016. For simple wells, annual groundwater withdrawal 

calculated in 2016 using the most recently measured PCCs 

is 5-percent less than withdrawal from dedicated flowmeters; 

annual groundwater withdrawal calculated in 2016 using 

valley average PCCs is the same as dedicated flowmeter 

withdrawal (table 14). For simple wells, annual groundwater 

withdrawal calculated in 2016 using historical mean, method 

4, or historical median PCCs, method 5, is 8 and 7 percent, 

respectively, greater than dedicated flowmeter withdrawal.

Annual groundwater withdrawal also was calculated for 

wells classified as borderline or with three or fewer historical 

PCC records. For these wells, the smallest percent difference 

from withdrawal from dedicated flowmeters, method 11, 

is withdrawal calculated using historical mean, method 4, 

historical median, method 5, PCCs for irrigation wells in 

2016. Also, for these wells, annual groundwater withdrawal 

calculated in 2016 using historical mean PCCs was 1-percent 

greater than dedicated flowmeter withdrawal; annual 

groundwater withdrawal calculated using historical median 

PCCs was 2-percent less than dedicated flowmeter withdrawal 

(table 15). Withdrawal calculated using valley average was 

7-percent less than dedicated flowmeter withdrawal, and 

withdrawal calculated using the most recently measured PCCs 

was 9-percent less than dedicated flowmeter withdrawal 

(table 15).
Findings 17

Table 12. Percent difference between estimated annual groundwater withdrawal calculated using various combinations of 

historical power consumption coefficients (PCCs) from irrigation wells that have historical PCCs, 2016 power usage, and dedicated 

flowmeters in Goshen Valley, Utah1, 2016.

[GW, groundwater; acre-ft, acre-foot]

Method 

number

Method 

1

Method 

2

Method 

3

Method 

4

Method 

5

Method 

6

Method 

7

Method 

8

Method 

9

Method 

10

Method 

11

Annual GW 

withdrawal 

(acre-ft)

Method 1 0 20 –34 –13 –14 –18 –31 7 19 –2 –9 14,888

Method 2 –17 0 –45 –28 –28 –32 –42 –11 –1 –19 –24 12,370

Method 3 51 81 0 30 30 24 5 61 80 47 37 22,416

Method 4 15 39 –23 0 0 –5 –20 23 38 13 5 17,182

Method 5 16 39 –23 0 0 –5 –20 24 38 13 5 17,241

Method 6 22 47 –19 6 5 0 –15 30 45 19 11 18,135

Method 7 44 73 –4 25 24 18 0 54 72 40 31 21,435

Method 8 –6 13 –38 –19 –19 –23 –35 0 12 –9 –15 13,925

Method 9 –16 1 –44 –27 –28 –31 –42 –10 0 –18 –24 12,477

Method 10 3 23 –32 –11 –11 –16 –29 10 22 0 –7 15,265

Method 11 10 32 –27 –5 –5 –10 –24 18 31 7 0 16,379

1This table includes active irrigation wells in Goshen Valley that have historical PCCs, 2016 power usage, and dedicated flowmeters. It excludes 10 

active irrigation wells that do not have dedicated flowmeters and 2016 power usage reported.

Table 13. Percent difference between estimated annual groundwater withdrawal 

calculated using various combinations of historical power consumption coefficients (PCCs) 

from complex irrigation wells that have historical PCCs, 2016 power usage, and dedicated 

flowmeters in Goshen Valley, Utah1, 2016.

[GW, groundwater; acre-ft, acre-foot]

Method 

number

Method 

1

Method 

2

Method 

3

Method 

4

Method 

5

Method 

10

Method 

11

Annual GW 

withdrawal 

(acre-ft)

Method 1 0 32 –45 –21 –25 –2 –12 3,980

Method 2 –24 0 –58 –40 –43 –26 –34 3,018

Method 3 82 140 0 43 36 78 59 7,228

Method 4 27 67 –30 0 –5 24 11 5,039

Method 5 34 76 –26 6 0 31 17 5,320

Method 10 2 34 –44 –20 –24 0 –11 4,053

Method 11 14 50 –37 –10 –15 12 0 4,539

1This table includes active irrigation wells classified as complex in Goshen Valley that have historical 

PCCs, 2016 power usage, and flowmeters. It excludes 10 active irrigation wells that do not have flowmeters 

and 2016 power usage reported.
18 Development of a Method to Identify Complex Wells and Assess the Accuracy of Basin Withdrawals in Utah

Table 14. Percent difference between estimated annual groundwater withdrawal 

calculated using various combinations of historical power consumption coefficients (PCCs) 

from simple irrigation wells that have historical PCCs, 2016 power usage, and dedicated 

flowmeters in Goshen Valley, Utah1, 2016.

[GW, groundwater; acre-ft, acre-foot]

Method 

number

Method 

1

Method 

2

Method 

3

Method 

4

Method 

5

Method 

10

Method 

11

Annual GW 

withdrawal 

(acre-ft)

Method 1 0 4 –25 –12 –11 –5 –5 2,925

Method 2 –4 0 –28 –16 –15 –8 –8 2,818

Method 3 34 39 0 17 18 27 27 3,906

Method 4 14 18 –15 0 1 8 8 3,339

Method 5 13 17 –15 –1 0 7 7 3,301

Method 10 5 9 –21 –8 –7 0 0 3,079

Method 11 5 9 –21 –8 –7 0 0 3,079

1This table includes active irrigation wells classified as simple in Goshen Valley that have historical PCCs, 

2016 power usage, and flowmeters. It excludes 10 active irrigation wells that do not have flowmeters and 

2016 power usage reported.

Table 15. Percent difference between estimated annual groundwater withdrawal 

calculated using various combinations of historical power consumption coefficients (PCCs) 

from borderline irrigation wells and wells with three or fewer historical PCCs that have 

historical PCCs, 2016 power usage, and dedicated flowmeters in Goshen Valley, Utah1, 2016.

[GW, groundwater; acre-ft, acre-foot]

Method 

number

Method 

1

Method 

2

Method 

3

Method 

4

Method 

5

Method 

10

Method 

11

Annual GW 

withdrawal 

(acre-ft)

Method 1 0 22 –29 –9 –7 –2 –9 7,982

Method 2 –18 0 –42 –26 –24 –20 –25 6,534

Method 3 41 73 0 28 31 39 29 11,282

Method 4 10 35 –22 0 2 8 1 8,805

Method 5 8 32 –24 –2 0 6 –2 8,621

Method 10 2 24 –28 –8 –6 0 –7 8,133

Method 11 10 34 –22 0 2 8 0 8,761

1This table includes active irrigation wells classified as borderline or with three or fewer historical PCCs in 

Goshen Valley that have historical PCCs, 2016 power usage, and flowmeters. It excludes 10 active irrigation 

wells that do not have flowmeters and 2016 power usage reported.
Findings 19

For wells classified as simple and borderline, historical 

mean and historical median methods were less than 8-percent 

different from dedicated flowmeter withdrawal. For wells 

classified as complex, historical mean and historical median 

methods were less than 17 percent, and most recent and 

valley average PCCs were 12 percent or less different from 

dedicated flowmeter withdrawal. Withdrawal estimates from 

individual wells could be improved with more frequent PCC 

measurements, with complex wells receiving the most benefit. 

Although there are uncertainties in estimates of withdrawal 

from individual wells, basin-wide withdrawal estimates 

incorporating all the wells (simple and complex) in a basin 

likely average some of the variability yielding more accurate 

estimates for the basin as a whole as compared to individual 

wells, especially with respect to complex wells.

Goshen Valley provides an opportunity to compare direct 

flow measurements with PCC estimated flow because Goshen 

Valley has 20 wells with dedicated flowmeters, 2016 power 

consumption data, and historical PCCs. The season-long PCC 

for each well can be calculated using the withdrawal from 

the dedicated flowmeter and the yearly power consumption. 

The season-long PCC calculated from dedicated flowmeters 

and the instantaneous measured PCC from the most recently 

measured PCCs was compared to assess what, if any, 

differences arise from using an instantaneous PCC compared 

to a season-long PCC (fig. 7). Season-long PCC compared to 

instantaneous PCC shows that there is no consistent bias using 

instantaneous PCCs.

0 0.5 1 1.5 2 2.5 3 3.5

0

0.5

1

1.5

2

2.5

3

3.5

Season-long dedicated flow meter PCC, in acre-feet/1,000 kWh

Instantaneous PCC, in acre-feet/1,000 kWh

Figure 7. Comparison of season-long power consumption coefficient (PCC) 

calculated from dedicated flowmeters and the instantaneous measured PCC from 

the most recently measured PCCs in Goshen Valley, Utah, using 20 wells with 

dedicated flowmeters, 2016 power consumption, and historical PCCs. [kWh, kilowatt 

per hour.]
20 Development of a Method to Identify Complex Wells and Assess the Accuracy of Basin Withdrawals in Utah

Summary

Historical power consumption coefficient (PCC) 

records can be used to classify wells as simple, complex, or 

borderline based on the coefficient of variation (CV). The 

percent difference between methods for calculating annual 

groundwater withdrawal in the Tooele, Parowan, and Goshen 

Valleys was calculated to assess what, if any, difference the 

combination of PCC values used to estimate groundwater 

withdrawal has on the basin’s estimated groundwater 

withdrawal. For all three test basins in 2016, using the 

historical mean PCC to calculate annual groundwater 

withdrawal is close to using the most recently measured PCC 

to calculated annual groundwater withdrawal. In Tooele, 

Parowan, and Goshen Valleys, withdrawal calculated using 

maximum and minimum historical PCCs differs by as much 

as 59 percent when compared to withdrawal calculated using 

the most recently measured PCCs (table 6). In Goshen Valley, 

withdrawal calculated using historical mean or historical 

median PCCs is closer to flowmeter reported withdrawal than 

withdrawal calculated using the most recently measured PCCs.

In Goshen Valley, using a subset of wells with both 

dedicated flowmeters and 2016 power usage, annual 

groundwater withdrawal calculated using historical mean 

PCCs was 5-percent greater than annual groundwater 

withdrawal measured using dedicated flowmeters (fig. 8). 

Annual groundwater withdrawal calculated using the most 

recently measured PCCs was 9-percent less than withdrawal 

from dedicated flowmeters. Assuming dedicated flowmeters 

represent the most accurate method available to estimate 

groundwater withdrawal, in the case of Goshen Valley, using 

historical mean PCCs to calculate withdrawal appears to be 

the most accurate of the methods evaluated (table 7; fig. 8). 

The historical mean could average out changes in system 

configuration and timing of the measurement rather than 

using a single most recently measured PCC. Regardless 

of the composition of well configuration in a basin, the 

implementation of dedicated flowmeters reduces uncertainty in 

basin-wide groundwater withdrawal estimates. Consequently, 

the historical mean PCC was compared to selected methods of 

estimating withdrawal in each of the three basins.

–60%

–40%

–20%

0%

20%

40%

60%

Maximum

Minimum

Most recent

Mean

Valley average

Dedicated flowmeter

Percent difference from dedicated flowmeter withdrawal (2016)

Goshen Valley

Figure 8. Percent difference between dedicated flowmeter 

withdrawal and withdrawal calculated using other methods 

in Goshen Valley, Utah, 2016.
Summary 21

The difference between annual groundwater withdrawal 

calculated using historical minimum PCCs, historical 

maximum PCCs, historical mean PCCs, valley average PCCs, 

and the most recently measured PCCs for all basins in 2016 

is shown in figure 9A. The difference between withdrawal 

calculated using these methods is larger for Parowan than 

Tooele and Goshen Valleys; however, approximately nine 

times more water is withdrawn in Parowan Valley than in 

Tooele Valley and two times more water is withdrawn in 

Parowan Valley than in Goshen Valley (fig. 9A). Normalizing 

these withdrawals allows for a direct comparison between 

differences in withdrawal calculated using different 

combinations of PCCs in each basin.

The normalized percent difference from withdrawal 

calculated with these methods and withdrawal calculated 

using historical mean PCCs is shown in figure 9B. Tooele 

Valley has the most complex wells (fig. 10A) and the largest 

normalized range of withdrawal when compared to withdrawal 

calculated using historical mean PCCs; 44-percent greater 

using historical maximum; and 32-percent less using historical 

minimum (fig. 9B; table 8). Parowan Valley has the most 

simple wells (fig. 10B) and the smallest normalized range of 

withdrawal; 17-percent greater using historical maximum and 

17-percent less using historical minimum (fig. 9B; table 9). 

Goshen Valley has more complex wells than Parowan Valley 

and fewer complex wells than Tooele Valley, and Goshen 

Valleys normalized range of withdrawals when compared 

to withdrawal calculated using historical mean PCCs is 

between these two basins; 29-percent greater using historical 

maximum and 27 percent using historical minimum (figs. 9B, 

10C; table 11). Based on the analysis of the three test basins, 

basins with a greater proportion of complex wells without 

dedicated flowmeters have greater uncertainty of estimated 

groundwater withdrawal than basins with a greater proportion 

of simple wells.

Maximum

Minimum

Most recent

Mean

Valley average

–60%

–40%

–20%

0%

20%

40%

60%

Normalized percent difference from historical mean calculated withdrawal, 2016

4,000

9,000

14,000

19,000

24,000

29,000

34,000

39,000

44,000

49,000

Estimated annual groundwater withdrawal, in acre-feet, 2016

Tooele

Valley

Parowan

Valley

Goshen

Valley

Tooele

Valley

Parowan

Valley

Goshen

Valley

Maximum

Minimum

Most recent

Mean

Valley average

A B

Figure 9. Estimated annual groundwater withdrawal calculated using historical minimum power consumption coefficients (PCCS). 

A, Historical maximum PCCs, historical mean PCCs, valley average PCCs, and the most recently measured PCCs; and B, Normalized 

percent difference between annual groundwater withdrawal calculated using historical mean PCCs and annual groundwater 

withdrawal calculated using other methods (historical minimum PCCs, historical maximum PCCs, valley average PCCs, and most 

recently measured PCCs) in 2016 for Tooele, Parowan, and Goshen Valleys, Utah. [%, percent.]
22 Development of a Method to Identify Complex Wells and Assess the Accuracy of Basin Withdrawals in Utah

A Tooele Valley

46 active irrigation wells in 2016

B Parowan Valley

115 active irrigation wells in 2016

C Goshen Valley

30 active irrigation wells in 2016

Dedicated 

flow meters

No dedicated 

flow meters

EXPLANATION

Complex wells Simple wells

Borderline wells ≤3 Historical measurements

EXPLANATION

Complex wells Simple wells

Borderline wells ≤3 Historical measurements

EXPLANATION

Complex wells (dedicated flow meters)

Simple wells (dedicated flow meters)

≤3 Historical measurements (dedicated flow meters)

≤3 Historical measurements (no dedicated flow meters)

Borderline wells (no dedicated flow meters)

Borderline wells (dedicated flow meters)

Figure 10. Wells classified as simple, complex, 

and borderline (three or fewer historical power 

consumption coefficients) in each basin, A, Tooele; 

B, Parowan; and C, Goshen, Utah, 2016.

Groundwater withdrawal estimates could be improved 

by incorporating methods and techniques outlined in this 

report. The CV could be calculated for each well in each 

basin across the state of Utah, where PCC records exist. The 

percentage of complex wells could then be determined based 

on the thresholds outlined in this paper. In basins with a high 

percentage of complex wells, field visits to verify correct 

classification could be done and repeat measurements of PCCs 

could be completed more frequently than in basins with more 

simple wells. The installation of dedicated flowmeters would 

improve estimates of basin-wide withdrawal, with installation 

on complex wells likely providing the most benefit. Similarly, 

if a well’s configuration is changed from simple to complex, 

then installation of a dedicated flowmeter would assist in 

withdrawal estimates.

Sources of variability of PCCs can be attributed to a 

variety of user and environmental factors, such as errors when 

measuring PCC caused by low pressure or the timing of the 

measurement. For instance, in a complex well system, one 

segment of the pipe could be in use during one visit, and the 

following visit, multiple pipes could be in use. These sources 

of variability contribute to the difficulty arising from using 

a single PCC to calculate withdrawal and support the use of 

mean or median PCCs, which lessen the effects of the large 

ranges in variability over time when annual groundwater 

withdrawal is calculated for an entire basin.
References Cited 23

References Cited

Dash, R.G., Troutman, B.M., and Edelmann, P., 1999, 

Comparison of two approaches for determining 

ground-water discharge and pumpage in the lower Arkansas 

River Basin, Colorado, 1997–98: U.S. Geological Survey 

Water-Resources Investigations Report 99–4221, 39 p., 

https://doi.org/10.3133/wri994221.

Gold, B.L., 2020, Historical power consumption coefficients 

and 2016 power usage for irrigation wells in Tooele, 

Parowan, and Goshen Valley, Utah: U.S. Geological Survey 

data release, https://doi.org/10.5066/P92UVVV6.

Hurr, R.T., and Litke, D.W., 1989, Estimating 

pumping time and groundwater withdrawals using 

energy-consumption data: U.S. Geological Survey 

Water-Resources Investigations Report 89–4107, 27 p., 

https://doi.org/10.3133/wri894107.

Marston, T.M., 2017, Water resources of Parowan 

Valley, Iron County, Utah: U.S. Geological Survey 

Scientific Investigation Report 2017–5033, 45 p., 

https://doi.org/10.3133/sir20175033.

Reed, G.F., Lynn, F., and Meade, B.D., 2002, Use 

of coefficient of variation in assessing variability 

of quantitative assays: Clinical and Diagnostic 

Laboratory Immunology, v. 9, no. 6, p. 1235–1239, 

https://doi.org/10.1128%2FCDLI.10.6.1162.2003.

Zwillinger, D., and Kokoska, S., 2000, CRC Standard 

probability and statistics tables and formulae: Boca Raton, 

FL, Imprint CRC Press, 200 p.

For more information concerning the research in this report, contact the

Director, Utah Water Science Center

U.S. Geological Survey

2329 West Orton Circle

Salt Lake City, Utah 84119-2047

801-908-5000

https://ut.water.usgs.gov

Publishing support provided by the U.S. Geological Survey 

Science Publishing Network, Sacramento Publishing Service Center
Gold and others—Development of a Method to Identify Complex Wells and Assess the Accuracy of Basin Withdrawals in Utah—OFR 2020–1106

ISSN 2331-1258 (online)

https://doi.org/10.3133/ofr20201106