Best Practices for Continuous

Monitoring of Temperature and Flow

in Wadeable Streams

National Center for Environmental Assessment

Office of Research and Development

EPA/600/R-13/170F | September 2014 | www.epa.gov/ncea
EPA/600/R-13/170F

September 2014

Best Practices for Continuous Monitoring of Temperature and 

Flow in Wadeable Streams

National Center for Environmental Assessment

Office of Research and Development

U.S. Environmental Protection Agency

Washington, DC 20460
DISCLAIMER

This document has been reviewed in accordance with U.S. Environmental Protection Agency 

and U.S. Geological Survey policy and approved for publication. Mention of trade names or 

commercial products does not constitute endorsement or recommendation for use, but is for 

descriptive purposes only. This document does not supplant official published methods and does 

not constitute an endorsement of a particular procedure or method. 

ABSTRACT

The United States Environmental Protection Agency (U.S. EPA) is working with its regional 

offices, states, tribes, river basin commissions and other entities to establish Regional Monitoring 

Networks (RMNs) for freshwater wadeable streams. To the extent possible, uninterrupted, 

biological, temperature and hydrologic data will be collected on an ongoing basis at RMN sites, 

which are primarily located on smaller, minimally disturbed forested streams. The primary 

purpose of this document is to provide guidance on how to collect accurate, year-round 

temperature and hydrologic data at ungaged wadeable stream sites. It addresses questions related 

to equipment needs, sensor configuration, sensor placement, installation techniques, data 

retrieval, and data processing. This guidance is intended to increase comparability of continuous 

temperature and hydrologic data collection at RMN sites and to ensure that the data are of 

sufficient quality to be used in future analyses. It also addresses challenges posed by year-round 

deployments. These data will be used for detecting temporal trends; providing information that 

will allow for a better understanding of relationships between biological, thermal, and hydrologic 

data; predicting and analyzing climate change impacts and quantifying natural variability.

Preferred citation: U.S. Environmental Protection Agency (EPA). (2014) Best Practices for Continuous 

Monitoring of Temperature and Flow in Wadeable Streams. Global Change Research Program, National 

Center for Environmental Assessment, Washington, DC; EPA/600/R-13/170F. Available from the 

National Technical Information Service, Springfield, VA, and online at http://www.epa.gov/ncea. 

ii
CONTENTS

TABLES ........................................................................................................................................ vi

FIGURES ...................................................................................................................................... vii

ABBREVIATIONS AND ACRONYMS ....................................................................................... x

PREFACE ...................................................................................................................................... xi

AUTHORS, CONTRIBUTORS, AND REVIEWERS ................................................................ xii

EXECUTIVE SUMMARY ......................................................................................................... xiii

1. PURPOSE AND SCOPE......................................................................................................... 1

2. TEMPERATURE .................................................................................................................... 3

2.1. Equipment ..................................................................................................................... 3

2.1.1. Basic components ............................................................................................... 3

2.1.2. Considerations when choosing temperature sensors .......................................... 3

2.1.3. Considerations when choosing portable data offload devices ............................ 5

2.1.4. Considerations when choosing radiation shields ................................................ 7

2.2. Pre-Deployment ............................................................................................................ 9

2.2.1. Accuracy check .................................................................................................. 9

2.2.2. Sensor configuration and launch ...................................................................... 12

2.3. Deployment of Water Temperature Sensors ............................................................... 14

2.3.1. Guidelines for placement within the stream ..................................................... 14

2.3.2. Installation ........................................................................................................ 15

2.3.3. Documentation ................................................................................................. 22

2.3.4. Common problems ........................................................................................... 25

2.4. Deployment of Air Temperature Sensors ................................................................... 26

2.5. Maintenance/Mid-Deployment Checks and Data Offload ......................................... 28

2.6. Quality Assurance and Control ................................................................................... 31

2.6.1. Mid- and post-deployment accuracy checks .................................................... 32

2.6.2. Error screening ................................................................................................. 32

2.6.3. Record keeping ................................................................................................. 35

iii
CONTENTS (continued)

3. HYDROLOGY ...................................................................................................................... 35

3.1. Equipment ................................................................................................................... 35

3.1.1. Basic components ............................................................................................. 35

3.1.2. Considerations when choosing pressure transducers ....................................... 36

3.1.3. Staff gage .......................................................................................................... 38

3.1.4. Protective housing ............................................................................................ 40

3.2. Pre-Deployment .......................................................................................................... 41

3.2.1. Accuracy Check ............................................................................................... 41

3.2.2. Sensor configuration and launch ...................................................................... 41

3.3. Deployment of Instream Pressure Transducers .......................................................... 43

3.3.1. Selecting a location .......................................................................................... 43

3.3.2. Staff gage installation ....................................................................................... 44

3.3.3. Pressure transducer installations ...................................................................... 46

3.4. Deployment of On-Land Components ........................................................................ 51

3.5. Elevation Surveys and Documentation ....................................................................... 53

3.6. Maintenance/Mid-Deployment Checks and Data Offload ......................................... 55

3.7. Quality Assurance and Control ................................................................................... 58

3.7.1. Accuracy checks ............................................................................................... 58

3.7.2. Error screening ................................................................................................. 59

3.8. Developing Stage-Discharge Rating Curves .............................................................. 61

3.8.1. When to measure discharge .............................................................................. 61

3.8.2. Equipment ........................................................................................................ 62

3.8.3. Site selection ..................................................................................................... 62

3.8.4. Measurements ................................................................................................... 63

3.8.5. Documentation ................................................................................................. 64

3.8.6. Quality assurance and control .......................................................................... 65

3.8.7. Making flow rating curves ............................................................................... 65

4. LITERATURE CITED .......................................................................................................... 66

iv
CONTENTS (continued)

APPENDICES

A. How to construct PVC housings for water temperature sensors with cable 

installations ............................................................................................................... A-1 

B. How to make and install homemade radiation shields for air temperature 

sensors ....................................................................................................................... B-1

C. Temperature sensor calibration forms ...................................................................... C-1

D. Temperature sensor deployment & tracking forms .................................................. D-1

E. Equipment lists for temperature sensor procedures ................................................... E-1

F. Examples of alternate temperature sensor installation techniques ............................ F-1

G. Temperature sensor mid-deployment check forms................................................... G-1

H. QA/QC checklist for temperature sensor data .......................................................... H-1

I. Equipment lists for pressure transducer procedures ................................................... I-1

J. Field forms for water level and flow measurements.................................................. J-1

K. QA/QC checklist for pressure transducer data.......................................................... K-1 

v
TABLES

Table 1. Specifications for temperature sensors used in the RMNs ............................................... 4

Table 2. Examples of commercially available temperature sensors ............................................... 6

Table 3. The “ice bucket” method can be used for single-point pre-deployment 

accuracy checks (MDDNR, no date) ............................................................................ 10

Table 4. Multi-point pre-deployment accuracy check .................................................................. 11

Table 5. Equipment needs for the pre-deployment accuracy check ............................................. 12

Table 6. Quick guide for doing underwater epoxy installations (Isaak et al. 2013) ..................... 16

Table 7. Equipment list for doing underwater epoxy installations (Isaak et al. 2013) ................. 18

Table 8. Guidelines for documenting the installation ................................................................... 23

Table 9. Equipment list for documenting sites ............................................................................. 25

Table 10. Tips for minimizing the chance of sensors being lost or damaged ............................... 26

Table 11. Checklists for performing maintenance/mid-deployment checks and data 

downloads ..................................................................................................................... 29

Table 12. Equipment list for conducting maintenance/mid-deployment checks and 

data downloads ............................................................................................................. 31

Table 13. Error screening procedure (Dunham et al. 2005, Sowder and Steel 2012, 

Personal communication, Michael Kashiwagi (MDDNR), April 17, 2014, 

Personal communication, Dustin Shull (PADEP), February 2, 2014) .......................... 33

Table 14. General summary of different types of problems that can occur with 

continuous temperature data and recommended actions for addressing them .............. 34

Table 15. Examples of commercially available pressure transducers .......................................... 39

Table 16. Equipment list for staff gage installation ...................................................................... 45

Table 17. Equipment list for transducer installation ..................................................................... 48

Table 18. Quick guide for elevation surveys of staff gages and transducers using an 

auto level ....................................................................................................................... 53

Table 19. Equipment list for elevation surveys ............................................................................ 54

Table 20. General summary of different types of problems that can occur with 

pressure transducer data and recommended actions for addressing them .................... 60

vi
FIGURES

Figure 1. Numerous temperature sensors are commercially available. .......................................... 5

Figure 2. Additional equipment is needed to offload data from the temperature 

sensors onto a computer.................................................................................................. 7

Figure 3. Stream temperature measurements from four sensors at the same site during 

eight days in July 2010.. ................................................................................................. 8

Figure 4. Unassembled components of an inexpensive PVC canister radiation shield 

for water temperature sensors (described in more detail in Isaak et al. 

2013). .............................................................................................................................. 9

Figure 5. Examples of radiation shields for air temperature sensors include A) the 

Gill-style Onset RS1 solar radiation shield (www.onsetcomp.com) and B) 

custom design by Zachary Holden (Appendix B). ....................................................... 10

Figure 6. Probability of underestimating the maximum daily temperature at least 1°C 

in relation to daily range of temperature and sampling interval (Dunham et 

al. 2005). ....................................................................................................................... 13

Figure 7. Examples of large rocks (a, b) and cement bridge pilings (c, d) that provide 

good sensor attachment sites......................................................................................... 17

Figure 8. Close-up of a PVC solar shield with a temperature sensor glued to a rock in 

a stream. ........................................................................................................................ 18

Figure 9. Equipment needed to permanently install temperature sensors in streams 

using underwater epoxy. ............................................................................................... 19

Figure 10. If conditions permit, attach sensors in two places, using heavy-duty (e.g., 

120-lb tensile strength) cable ties. ................................................................................ 20

Figure 11. Using bent rebar for rebar installations has several advantages. It is more 

secure because the metal bar is anchored in two places. .............................................. 21

Figure 12. Example of how a cable and rebar installation is configured for large 

streams in Maryland...................................................................................................... 21

Figure 13. Example of a rebar installation in a small stream in Shenandoah National 

Park, VA. ...................................................................................................................... 22

Figure 14. Example of a hand-drawn map from a field form used by the Washington 

State Department of Ecology (taken from Ward 2011)................................................ 24

Figure 15. Metal forestry tags can be attached to the downstream side of large rocks 

to monument sites and air in relocation of sensors (Isaak et al. 2013). ........................ 24

Figure 16. Numerous pressure transducers are commercially available....................................... 38

vii
FIGURES (continued)

Figure 17. Example of a USGS style staff gage (Type A) marked in 0.02-foot 

increments..................................................................................................................... 40

Figure 18. Example of a protective housing made of PVC pipe. This one is for a 

vented pressure transducer, which is secured inside the pipe with zip ties. ................. 40

Figure 19. Some transducers come in a protective metal case and do not need to be 

encased in an additional housing. ................................................................................. 41

Figure 20. Staff gage readings provide a quality check of transducer data. ................................. 42

Figure 21. Examples of controls downstream of staff gages include A. riffle and B. 

culvert. .......................................................................................................................... 44

Figure 22. Examples of gage installation techniques include A. streambed, B. fixed 

object – bridge wing wall, and C. fixed object – boulder............................................. 44

Figure 23. Example of a 0.5-inch by 3.75-inch wedge anchor with bolt and washer................... 46

Figure 24. Non-vented pressure transducer installation. .............................................................. 47

Figure 25. Non-vented (left) and vented (right) pressure transducers attached to staff 

gage board using conduit hangars................................................................................. 48

Figure 26. Examples of streambed installations of pressure transducers using rebar. ................. 50

Figure 27. Vented transducer data logger installation. The transducer is attached to 

the tree with stainless steel conduit straps. ................................................................... 51

Figure 28. Barometric pressure sensor installation for a non-vented transducer, A. 

without the PVC cap and B. with the PVC cap. ........................................................... 52

Figure 29. Examples of auto level and tripod used for elevation survey (A) and 

permanent structure used as a benchmark (B). ............................................................. 54

Figure 30. An example of a completed elevation survey form..................................................... 56

Figure 31. Data download from vented transducer with external data logger on land 

using computer and cable (left) and non-vented transducer with internal 

data logger using computer and data shuttle (right). .................................................... 58

Figure 32. Example of a transducer download field data sheet. ................................................... 58

Figure 33. A culvert replacement downstream of a stream gage on Gulf Brook in 

Pepperell, MA caused enough of a channel change to necessitate a new 

rating curve. .................................................................................................................. 62

Figure 34. Examples of good cross-sections for making discharge measurements...................... 63

viii
FIGURES (continued)

Figure 35. Layout of a channel cross-section for obtaining discharge data, using the 

velocity-area procedure. ................................................................................................ 64

Figure 36. Example of regular (left) and log-log scale (right) rating curves created 

using Aquatic Informatics’ AQUARIUS software. ...................................................... 66

ix
ABBREVIATIONS AND ACRONYMS

DRBC Delaware River Basin Commission

DTS distributed temperature sensing

FMU Freshwater Monitoring Unit

GPS global positioning system

GZF gage height of zero flow

NIST National Institute of Standards and Technology 

PVC polyvinyl chloride

PZF point of zero flow

RIFLS River Instream Flow Stewards Program

RMN Regional Monitoring Network

QAPP quality assurance project plan

QA/QC quality assurance/quality control

SOP standard operating procedures

TIR thermal infrared

U.S. EPA United States Environmental Protection Agency

USGS United States Geological Survey

x
PREFACE

This guidance document was prepared by Tetra Tech, Inc., the Massachusetts Department of 

Fish and Game/Division of Ecological Restoration, the U.S. Forest Service, the Massachusetts 

Cooperative Fish and Wildlife Research Unit of the U.S. Geological Survey, the U.S. 

Environmental Protection Agency Region 3 office, and the Global Change Assessment Staff in 

the Air, Climate, and Energy Program at the U.S. Environmental Protection Agency. The 

document facilitates more uniform and effective collection of continuous temperature and stage 

(depth) data at ungaged sites in wadeable streams, and addresses questions related to equipment 

needs, sensor configuration, sensor placement, installation techniques, data retrieval, and data 

processing.

xi
AUTHORS, CONTRIBUTORS, AND REVIEWERS

The Global Change Assessment Staff (GCAS) in the Air, Climate, and Energy (ACE) Program 

of the National Center for Environmental Assessment, Office of Research and Development, 

U.S. Environmental Protection Agency (EPA) is responsible for publishing this report. Tetra 

Tech, Inc. prepared this document under Contract No. EP-C-12-060; EPA Work Assignment No.

0-01. Dr. Britta Bierwagen served as the Technical Project Officer.

AUTHORS

Center for Ecological Sciences, Tetra Tech, Inc., Owings Mills, MD

Jen Stamp, Anna Hamilton

Massachusetts Department of Fish and Game, Division of Ecological Restoration, Boston, MA

Michelle Craddock, Laila Parker

U.S. Geological Survey, Massachusetts Cooperative Fish and Wildlife Research Unit, Amherst, 

MA

Allison H. Roy

U.S. Forest Service, Rocky Mountain Research Station, Boise, ID

Daniel J. Isaak

U.S. Forest Service, Missoula, MT

Zachary Holden

U.S. EPA Region 3, Wheeling, WV

Margaret Passmore

U.S. EPA, Office of Research and Development, Washington DC

Britta G. Bierwagen

REVIEWERS

U.S. EPA Reviewers

Richard Mitchell, Joe Flotemersch, and Lil Herger

External Reviewers

Hunter Carrick (Central Michigan University), Mark Rains (University of South Florida), John 

Yearsley (University of Washington)

ACKNOWLEDGMENTS

The authors would like to thank the many partners who reviewed early versions of this draft for 

clarity and usefulness. Their comments and input have substantially improved this document.

xii
EXECUTIVE SUMMARY

The United States Environmental Protection Agency (U.S. EPA) is working with its regional 

offices, states, tribes, river basin commissions, and other entities to establish Regional 

Monitoring Networks (RMNs) for freshwater wadeable streams. To date, RMNs have been 

established in the Northeast, Mid-Atlantic, and Southeast. Approximately 30 RMN sites are 

being monitored in each region. Many of these sites are located on smaller, minimally disturbed 

streams in forested watersheds with drainage areas less than 100 km2. To the extent possible, 

uninterrupted, biological, temperature, and hydrologic data will be collected on an ongoing basis 

at RMN sites. Several entities already conduct annual monitoring at targeted sites through 

existing programs. The goal is to integrate the RMNs into such existing programs. By 

coordinating efforts regionally, resources can be pooled efficiently. Detailed information about 

the development of the RMNs, including site selection criteria, biological sampling protocols, 

and data usage, is compiled in a separate report.

The primary purpose of this document is to provide guidance on how to collect accurate, yearround temperature and hydrologic data at ungaged wadeable stream sites. It addresses questions 

related to equipment needs, sensor configuration, sensor placement, installation techniques, data 

retrieval, and data processing. The protocols in this report describe simple methods and reference 

inexpensive tools for collecting data sustainably over the long term. This guidance is intended to 

increase comparability of continuous temperature and hydrologic data collection at RMN sites 

and to ensure that the data are of sufficient quality to be used in future analyses. It also addresses 

challenges posed by year-round deployments. These data will be used for detecting temporal 

trends; providing information that will allow for a better understanding of relationships between 

biological, thermal, and hydrologic data; predicting and analyzing climate change impacts; and 

quantifying natural variability.

The section of this document on temperature describes protocols for measuring continuous water 

and air temperature. At least one water and air temperature sensor should be deployed at each 

RMN site. The air temperature data will be used to help determine if water temperature sensors 

are dewatered during their deployment and will also provide important insights about the 

responsiveness of stream temperatures to air temperatures and the differing vulnerabilities of 

streams to thermal change. Two installation techniques for water temperature sensors are 

described in this document: the underwater epoxy method and a method in which cabling is used 

to attach the sensor to rebar or stable instream structures. 

The hydrology section describes how to install and maintain vented and unvented pressure 

transducers that measure continuous stage (depth). Staff gages should also be installed at RMN 

sites because they provide a means for checking the accuracy of the transducer data. This report 

also includes a brief section on how to take discharge measurements and develop stage-discharge 

curves. Taken alone, stage measurements yield some information about streamflow patterns, 

including the timing, frequency, and duration of high flows, but to better assess patterns and 

changes in stream hydrology, converting stage measurements into streamflow is most useful.

This document also describes how to accurately geo-reference and document the temperature 

sensors and pressure transducers in a way that enables field personnel to relocate them during 

xiii
subsequent visits. Efforts should be made to revisit the sites within the first month of installation 

to confirm that the installations are holding properly. After these initial deployment checks, sites 

should be visited as frequently as schedules allow to check the condition of the equipment, 

gather data for mid-deployment accuracy checks, and offload data. 

After data are offloaded, quality assurance and quality control (QA/QC) procedures are 

performed to verify the quality of the data and to check for potential errors. In this document, we 

describe a series of checks to perform on the data, including identifying and removing 

observations recorded before and after the equipment is correctly positioned and plotting 

measurements to check visually for missing data, outliers, and other abnormalities. Large 

amounts of data will accumulate quickly so a central database should be developed and 

maintained from the initial stages of monitoring. Any changes made to the data should be 

carefully documented, and all data forms should be organized, easily accessible, and archived in 

a way that allows for safe, long-term storage. 

xiv
1. PURPOSE AND SCOPE

The United States Environmental Protection Agency (U.S. EPA) is working with its regional 

offices, states, tribes, river basin commissions and other entities to establish Regional Monitoring 

Networks (RMNs) at which long-term biological, thermal, and hydrologic data will be collected 

from freshwater wadeable streams. At this time, RMNs have been established in the Northeast, 

Mid-Atlantic, and Southeast, and these efforts are being expanded into other regions. 

When selecting sites for the RMNs, attempts have been made to utilize and build on data already 

being collected by participating entities. Site selection considerations include low level of 

anthropogenic disturbance; long historical sampling record for biological, thermal, or 

hydrological data; sustainability (e.g., accessibility, partners); classification; level of protection;

and expected vulnerability to climate change. Approximately 30 RMN sites are being monitored 

in each region. Many of these sites are located on smaller, minimally disturbed streams in 

forested watersheds with drainage areas less than 100 km2.

The need for the RMNs stems from the lack of long-term, contemporaneous biological, 

temperature, and flow data, particularly at minimally disturbed, freshwater wadeable stream sites 

(Jackson and Fureder 2006, Mazor et al. 2009, Kennen et al. 2011, Isaak et al. 2012). To the 

extent possible, uninterrupted, biological, temperature, and hydrologic data will be collected on 

an ongoing basis at RMN sites. These data will be used for detecting temporal trends; providing 

information that will allow for a better understanding of relationships between biological, 

thermal, and hydrologic data; providing information about response and recovery of organisms 

to extreme weather events; analyzing climate change impacts (e.g., the National Climate 

Assessment Indicator System); testing hypotheses and predictive models related to climate 

change vulnerability; and quantifying natural variability. Several entities already conduct annual 

monitoring at targeted sites through existing programs. The goal is to integrate the RMNs into 

such existing programs. By coordinating efforts regionally, resources can be pooled to gain 

efficiencies. More detailed information about the RMNs, including site selection criteria, 

biological sampling protocols, and data usage, can be found in a separate report (U.S. EPA 

2014).

The primary purpose of this document is to provide guidance on how to collect accurate, yearround temperature and hydrologic data at ungaged wadeable stream sites. It addresses questions 

related to equipment needs, sensor configuration, sensor placement, installation techniques, data 

retrieval, and data processing. This guidance is intended to increase comparability of continuous 

temperature and hydrologic data collection at RMN sites and to ensure that the data are of 

sufficient quality to be used in future analyses. It also addresses challenges posed by year-round 

deployments. Year-round monitoring of temperature and hydrology is fundamental to 

understanding aquatic ecology. Although more and more continuous data are being collected, 

many of these data are not being collected year-round. For example, considerable amounts of 

stream temperature data are now routinely collected using inexpensive temperature sensors, but 

many of the temperature measurements are made only during summer months due to logistical 

constraints associated with stream access, concerns that large annual floods will destroy sensor 

installations, and an intentional focus on the summer season because it captures a critical time 

period for most aquatic species’ survival. Summer-only data provide a narrow view of thermal 

1
regimes in streams and misses ecologically relevant information about the date of spring onset, 

growing season length, overall variability, and total annual thermal units. 

Flow regime (magnitude, frequency, duration, timing, and rate of change) also strongly

influences stream ecology (Poff et al. 1997). The U.S. Geological Survey (USGS) has been 

collecting continuous hydrologic data in streams since 1889, and currently maintains over 7,000 

continuous gages. The USGS stream monitoring network provides critical, long-term, high 

quality information about our nation’s streams and rivers that can be used for planning and trend 

analysis (e.g., flood forecasting, water allocation, wastewater treatment, and recreation). Many 

USGS stream gages are located in large rivers that have multiple human uses. Most RMN sites 

are located on smaller, minimally disturbed forested streams with drainage areas less than 100 

km2, so only a limited number can be co-located with USGS gages. This necessitates that 

hydrologic data be collected independently. The collection of year-round hydrologic data from

headwater and mid-order streams is important. Streams of this size are instrumental in 

connecting upland and riparian systems with river systems (Vannote et al. 1980). Moreover, 

small upland streams, which are inhabited by temperature-sensitive organisms, are likely to 

experience substantial impacts from climate change (Durance and Ormerod 2007) and could also 

serve as refugia from the extremes in temperature and flow that are projected to occur (Meyer et 

al. 2007).

This report is divided into two main sections: one on temperature and one on hydrology. The 

temperature section describes protocols for measuring continuous water and air temperature. The 

hydrology section discusses how to install and maintain pressure transducers and staff gages to 

measure continuous stage (depth), and also includes a brief section on how to make discharge 

measurements to develop stage-discharge curves. The protocols in this report describe simple 

methods and reference inexpensive tools for collecting data sustainably over the long term. 

Although more advanced equipment is available, such as distributed temperature sensing (DTS) 

(Selker et al. 2006) and thermal infrared (TIR) imagery (Torgerson et al. 2001), most RMN 

members lack the resources to purchase and deploy these types of advanced equipment at 

numerous sites for long periods of time. Thus, they are not covered in this report. Temperature 

and hydrologic modeling are also considered to be outside the scope of this report. 

Although this document was written for the RMNs, much of the information and detail (e.g., data 

forms) is useful to entities that are developing quality assurance project plans (QAPPs) and 

standard operating procedures documents (SOPs) for measuring stream temperature and 

hydrologic data with pressure transducers. We recognize that entities like USGS and some 

monitoring programs have been early adopters of continuous sensor technology and have written 

their own protocols for deploying temperature sensors and pressure transducers (e.g., MDDNR 

no date, Danielson 2006, Wagner et al. 2006, Wilde 2006). The information in this document is 

not meant to replace those SOPs, but it might supplement them. This document differs from 

existing SOPs in that both temperature and stage (depth) information are compiled into one 

place, and deployment techniques specifically address challenges posed by year-round 

deployment. Although we attempted to make this document as comprehensive as possible, we 

acknowledge that certain situations might warrant an alternative methodology, procedure, or 

process. Future updates and improvements will be made as we receive feedback from partners 

who are field-testing these methodologies.

2
2. TEMPERATURE

This section describes protocols for measuring continuous water and air temperature. At least 

one water and air temperature sensor should be deployed at each RMN site. The air temperature 

data will be used to gain a better understanding of the relationship between air and water 

temperature at each RMN site. This will provide important insights about the responsiveness of 

stream temperatures to air temperatures and the differing vulnerabilities of streams to thermal 

change. The data will also be used for quality assurance and quality control (QA/QC) procedures 

(e.g., to help determine whether water temperature sensors are dewatered during their 

deployment).

The protocols described in this section are based on a review of existing temperature protocols 

from the Washington State Department of Ecology (Ward 2003, Bilhimer and Stohr 2009, Ward 

2011), the U.S. Forest Service (Dunham et al. 2005, Isaak and Horan 2011, Sowder and Steel 

2012, Isaak et al. 2013, Holden et al. 2013), Alaska (Mauger 2008), and Maryland (MDDNR, no 

date).

2.1. Equipment

This section describes equipment needed for collecting air and water temperature data and 

discusses considerations that influence equipment selection. 

2.1.1. Basic components

The following basic components are needed to collect and access continuous temperature 

measurements:

• A temperature sensor

• A data offload device that is compatible with the model of the sensor

• A computer with software that is compatible with the data offload device 

• A radiation shield to prevent direct solar radiation from hitting the sensor (this can also 

serve as a protective housing)

Additional equipment is needed to install the temperature sensors. This is discussed in more 

detail in Section 2.3.2.

2.1.2. Considerations when choosing temperature sensors

When selecting temperature sensors, consider factors such as durability, accuracy, resolution, 

measurement range, memory, and battery life. For RMN sites, select sensors that are durable 

(able to withstand years of use in challenging conditions), have a minimum accuracy of ±0.5°C, 

capture the full range of expected temperatures, have a memory that is sufficient to record 

measurements at 30-minute intervals during the deployment period, and have adequate battery 

life (Table 1). Water temperature sensors should be waterproof (e.g., IP code level 8). Sensors 

are available that can measure water temperature with accuracies of ±0.2°C. If resources permit, 

consider using these more accurate water temperature sensors at RMN sites.

3
Definitions of accuracy, precision, 

resolution, and bias

Accuracy refers to how close the temperature 

measurement is to its “true” value, or its 

“correctness.” Precision is the degree to which 

repeated measurements produce the same 

results, assuming conditions are unchanged 

(also referred to as variance or “tightness”).

Resolution is the smallest change that the sensor 

can detect, or the “fineness” to which the sensor 

can be read. Bias refers to whether a systematic 

offset occurs between the measured value and 

the “true” value.

The lifespan of the sensor should be another 

consideration. Some sensors are made to last 

five years or longer before their batteries 

expire or their cases start to leak. If sensors 

with non-replaceable batteries are used, 

document the sensor’s use so you know when 

to remove them from circulation and 

budget/plan for their replacement. Perform 

accuracy checks (Sections 2.2.1 and 2.6.1) to 

ensure that sensors meet the specifications 

quoted by the manufacturers. If these steps are 

taken, any errors associated with equipment 

differences will be extremely small compared 

to the temperature variability within and 

among sites.

Table 1. Specifications for temperature sensors used in the RMNs

Characteristic Water sensor Air sensor

Submersible/waterproof yes1 optional

Programmable start time and date yes yes

Minimum accuracy2 ±0.5°C3 ±0.5°C

Resolution4 <0.5°C <0.5°C

Measurement range – able to capture 

the full range of expected temperatures 

−5 to 37 ̊C will 

typically work

depending on the location, 

−20 to 50 ̊C might be necessary 

(a typically available range)

Memory Sufficient to record measurements at 30-minute intervals 

during deployment period 

Battery life Sufficient to remain active during deployment period

1

Sometimes sensors that are not waterproof are used to measure water temperature. This is done by housing them in 

waterproof, non-drilled PVC canisters. However, laboratory trials suggest a time lag between changes in water 

temperature and air temperature within a canister (Dunham et al. 2005).

2

Accuracy varies depending on temperature range; make sure the sensor can accurately record measurements over 

the temperature range that you expect the sensor to commonly experience. 3

Water temperature sensors with accuracies of ±0.2°C are currently available. Their use at RMN sites is encouraged. 4

Resolution is the smallest detectable increment that the sensor can measure; it needs to be less than the accuracy.

If the pressure transducer that I am purchasing can measure water temperature, do I need to 

purchase a separate temperature sensor?

It depends. If the temperature sensor in the transducer meets the minimum accuracy of ±0.5°C and the 

sensor placement conditions described in Section 2.3.1 are met, deploying a separate temperature 

sensor is unnecessary. Having a separate temperature sensor, however, does have some advantages. 

For one, it can serve as a back-up if the transducer unexpectedly fails. Data from the temperature 

sensor can also be used for quality control checks on the transducer data. 

4
The same sensors that are used for measuring water temperature can be used to measure air 

temperature provided they capture the full range of air temperatures that are expected to occur at 

a site (depending on the location, a range of −20 ̊C to 50 ̊C might be necessary). Less expensive, 

non-waterproof sensors can also be used to measure air temperature, provided the sensors are 

protected from the elements (see Table 2). Radiation shields, which are discussed in Section 

2.1.4, can serve this purpose. 

Examples of some commercially available temperature sensors are found in Table 2, and pictures 

of these sensors are shown in Figure 1.

Figure 1. Numerous temperature sensors are commercially available. Examples include: A) 

Onset Hobo© Water Temp Pro v2; B) Onset Tidbit© v2; C) Gemini Tinytag Aquatic 2; D) 

Thermoworks LogTag; E) MadgeTech Temp 101A; and F) Maxim Integrated Products 

Thermochron ibutton.

If different sites have different makes and models of temperature sensors, how much variability 

will this introduce? 

Not much, provided the proper accuracy checks are performed to ensure that sensors meet the 

specifications quoted by the manufacturers. Any errors associated with equipment differences are 

extremely small compared to the temperature variability within and among sites. 

2.1.3. Considerations when choosing portable data offload devices

A data offload device is typically a pocket-sized device called a base station that is sold by the 

manufacturer of a sensor. For example, the Onset sensors use a coupler specific to the model of 

the sensor, which must be attached to the sensor before the sensor can be connected to the base 

station. The base station is then connected to a computer via a cable (Figure 2). To view the data, 

the appropriate software must be installed on the computer. 

5
Table 2. Examples of commercially available temperature sensors

Manufacturer (website) Sensor model Waterproof Temperature range Accuracy1 Resolution1

Battery life 

(typical use) 

and 

replaceability

Approximate 

price2 ($) 

Onset (onsetcomp.com)

Hobo© Water 

Temp Pro v2 

(U22-001)

yes

–40° to 70°C (air); 

maximum sustained 

water = 50°C 

0.2°C from 

0° to 50°C 

0.02°C at 

25°C 

6 years, 

factoryreplaceable123 

TidbiT© v2 Temp 

Sensor (UTBI001)yes

–20° to 70°C (air); 

maximum sustained 

water = 30°C

0.2°C from 

0° to 50°C 

0.02°C at 

25°C 

5 years, nonreplaceable 133 

Hobo© U20 Water 

Level Logger 

(U20-001-04)

yes –20° to 50°C (air) 0.44 from 0° 

to 50°C

0.10°C at 

25°C

5 years, 

factoryreplaceable495 

Gemini 

(geminidataloggers.com) 

Tinytag Aquatic 2 

(TG-4100) yes –40° to 70°C 0.5°C from 

0°C to 50°C 0.01°C 1 year, userreplaceable 170 

Maxim Integrated 

Products 

(maximintegrated.com)

Thermochronibutton (DS1922L) no –40° to 85°C 

0.5°C from –

10°C to 

+65°C (with 

software 

correction)

0.5°C 

(8-Bit) or 

0.06°C (11-

Bit)

4 years, nonreplaceable 35 

Thermoworks 

(thermoworks.com) Log Tag no –40° to 85°C 0.5°C from –20 to 40°C <0.1°C 

2 to 3 years, 

technicianreplaceable35 

MadgeTech 

(madgetech.com) Temp101A no –40° to 80°C 0.5°C 0.01°C 10 years, userreplaceable 89 

1

Accuracy and resolution over additional temperature ranges can be found on the manufacturer specification sheets. 2

As of January 2013 and subject to change; reduced prices might be available for bulk orders.

6
Figure 2. Additional equipment is needed to offload data from the temperature sensors onto 

a computer. This figure depicts the coupler, base station, and USB cable needed to download 

data from the Onset Tidbit© v2 sensor (www.onsetcomp.com). A waterproof shuttle can also 

be used in place of the base station for on-site data offload and temporary data storage. 

These devices must be compatible with the make and model of the sensor.

Some manufacturers make small, portable waterproof devices (often referred to as shuttles) that 

can offload data while the sensor remains in the stream. These devices, which can be used to 

temporarily store the data and can also serve as base stations, are more expensive than the nonwaterproof base stations. At RMN sites, instream data offloads are generally not possible 

because sensors are housed in radiation shields (Section 2.1.4) and the sensors must be removed 

from these shields before they can be attached to the data offload device. Thus, the main benefits 

of the waterproof shuttles are that, after sensors are removed from the stream, field personnel can 

work with them in inclement weather, and they are easy to carry in and out of remote sites where 

bringing a laptop is impractical. 

Consider compatibility when purchasing equipment. Ensure that the data offload device and 

software are compatible with the model of the temperature sensor. If purchasing multiple 

sensors, buying the same model is often the most cost-effective because reduced prices might be 

available for bulk orders and only one data offload device and one software package are 

necessary for that particular model of sensor. The non-waterproof data offload device/base 

station for the Onset Tidbit© v2 Temp Sensor costs approximately $118, software costs $89–99, 

and the waterproof shuttle costs $237 (these represent approximate prices on the Onset website 

[http://www.onsetcomp.com/] as of June 2013). 

2.1.4. Considerations when choosing radiation shields 

Temperature sensors should be outfitted with radiation shields so that sunlight striking the 

sensors will not bias temperature readings (Figure 3) (Dunham et al. 2005, Isaak and Horan 

2011). These shields can also serve as protective housings and provide secure attachment points 

for the temperature sensors. Radiation shields can be purchased from a manufacturer or 

constructed less expensively from materials purchased at a local hardware store. 

7
Figure 3. Stream temperature measurements from four sensors at the same site during eight 

days in July 2010. All sensors had solar shields during the first four days when temperature 

measurements overlap. The solar shield was removed from one sensor on day 5 (black arrow) 

and temperature spikes became apparent when sunlight struck the sensor (reproduced from 

Isaak and Horan 2011).

As an example, a polyvinyl chloride (PVC) 

canister, which is simple and inexpensive to 

construct, can be used to shield the water 

temperature sensors. The one shown in Figure 4

consists of two pieces, including a flat, solid 

bottom and a screw-top cap. Several holes are 

drilled into the canister to make it neutrally 

buoyant and to facilitate water circulation. The 

threads are wrapped with Teflon tape, and then 

a small piece of neoprene is zip-tied to the 

temperature sensor to hold it inside the cap 

(Isaak et al. 2013). If using the underwater 

epoxy installation method (described in Section 

2.3.2), the PVC canister must have a lip at the 

bottom around which the epoxy can be wrapped 

or else the epoxy will not hold the PVC to the 

rock. More details on how to construct PVC 

canister shields, including specific part 

numbers, can be found in Isaak et al. (2013). An 

alternative method for constructing PVC 

canisters is described in Appendix A (Mauger 

2008). 

8

Does the color of the radiation shield 

matter?

Clear shields have been shown to cause 

erroneously high readings (Dunham et al. 

2005). For opaque shields, there is no 

evidence that color affects temperature 

readings, likely because the shield comes in 

minimal contact with the sensor and 

flowing water removes effects of heat 

conduction. 

Color does, however, affect visibility. 

White shields facilitate sensor retrieval 

because they are easily seen but their 

increased visibility could also increase 

vandalism rates, especially in heavily 

trafficked areas. If vandalism is a concern, 

use radiation shields that are neutral in color 

or paint them to reduce their visibility. 
Figure 4. Unassembled components of an inexpensive PVC canister radiation shield for water 

temperature sensors (described in more detail in Isaak et al. 2013). 

For air temperature sensors, the most effective radiation shields are mechanically aspirated, with 

a small fan located within the shield that maintains air flow through the shield in low wind 

conditions. Because these devices require power, passive/non-aspirated designs are more suitable

for remote deployment. 

A wide range of passive radiation shields are commercially available, and their effectiveness

varies with the type or brand of funnel. The standard shield used in most weather/climate stations 

is called a Gill radiation shield (Gill 1979). This shield is a series of plates that reflect incoming 

radiation and passively radiate accumulated heat via conduction (see Figure 5A). In areas with 

persistent winter and spring snowpack, the radiation shield should block incident radiation not 

just from above, but also from below, because radiation reflecting off the snow can directly 

strike sensors and bias temperature readings (Holden et al. 2013).

Commercially available, passive shields (e.g., Decagon Devices Inc., Campell Scientific, Onset 

Inc.) can be purchased for approximately $50–80 each. The custom-made version developed by 

Zachary Holden (Appendix B; Figure 5B) costs approximately $2.50–3.00 per shield. Holden 

tested his design and found that it performed well compared to commercially available shields 

(Holden et al. 2013). A YouTube video (accessed 15 June 2013) with instructions on how to 

construct the custom-made shield can be found at: www.youtube.com/watch?v=LkVmJRsw5vs.

Other designs for air temperature shields are also available. For example, some entities use a 

modified version of the PVC canister shown in Figure 4. The modified version differs in that it 

has larger, more numerous holes. When selecting a design, consider whether the performance of 

the shield has been tested and documented (e.g., compared against “known” validation 

temperature records to determine error rates). 

2.2. Pre-Deployment

2.2.1. Accuracy check

Before deploying the temperature sensors in the field, perform an accuracy check to verify that 

the sensors meet the accuracy quoted by the manufacturer. Also check the battery life and make 

sure the sensors are launching and downloading data properly. Temperature sensors with low 

battery levels should be removed from circulation. 

9
Figure 5. Examples of radiation shields for air temperature sensors include A) the Gill-style 

Onset RS1 solar radiation shield (www.onsetcomp.com) and B) custom design by Zachary

Holden (Appendix B).

Perform either a single- or multi-point accuracy check. A simple and effective procedure for 

performing single-point accuracy checks on water temperature sensors is the “ice bucket” 

method, in which sensors are placed in an ice bath for several hours and sensor readings are 

checked against readings from a National Institute of Standards and Technology (NIST)-certified 

thermometer. Table 3 contains step-by-step procedures for the “ice bucket” method that the 

Maryland Department of Natural Resources (MDDNR, no date) uses. Similar techniques are 

described in Onset Computer Corporation (2014) and Dunham et al. (2005). 

Table 3. The “ice bucket” method can be used for single-point pre-deployment accuracy 

checks (MDDNR, no date) 

Task Procedure

Setup

1. Prepare an ice bath in a large cooler (e.g., 48 quart). Fill the cooler half full with water 

and add 10 lbs. of ice. Be sure to use fresh water (dissolved minerals can alter the 

thermal properties of water). Place an air stone in the bottom of the ice bath to ensure 

mixing of the water. 

2. Allow the ice bath to sit for 2 hours to allow water temperature to stabilize. 

3. Measure the temperature of the ice bath using a NIST-certified thermometer. The 

temperature should read 0°C.

4. Prepare the sensors by connecting them to a computer and programming them to record 

at 2-minute intervals.

Test

5. Put sensors in the cooler (sensor side down). The sensors should be fully submerged.

6. Leave the sensors in the ice bath for a minimum of 1 hour. 

7. Remove the sensors from the cooler.

Accuracy 

check

8. Download the data from each sensor and plot the measurements

9. The final sensor measurements should be within ±0.5°C of the NIST-certified 

thermometer readings. If the sensors are outside that range, separate them out for further 

testing or return them to the manufacturer.

10. Record the data on an accuracy check datasheet (see example in Appendix C).

10
The multi-point check, which is described in Table 4, is more rigorous. First, sensors are set up 

to record at the same sampling intervals that will be used in the field (e.g., every 30 minutes at 

RMN sites). Next, the sensors are exposed to alternating warm and cold cycles that approximate 

the temperatures and duration of diurnal fluxes to which the sensors will be exposed in the field. 

At various points during this process, temperature measurements are taken with a NIST-certified 

thermometer. After the sensors complete these cycles, the data are downloaded onto a computer 

and values from the sensors are checked against: 1) readings that are taken with the NISTcertified thermometer; and 2) mean values obtained from the other sensors (any one sensor 

recording a value far from the other sensors is likely inaccurate, according to Sowder and Steel 

2012). The mean is used for the calibration accuracy check because it is based on multiple 

measurements and is generally more stable than single-point measurements like the minimum 

and maximum. The same procedures can be used for waterproof and non-waterproof sensors, 

except the non-waterproof sensors should not be placed in water baths. 

Table 4. Multi-point pre-deployment accuracy check

Task Procedure

Setup

1. Connect sensor to computer.

2. Check battery health. 

3. Program sensor to record at 30-minute intervals. 

Test bath

4. Put sensors in an open container/s; for the water temperature sensors, fill container with 

enough water to fully submerge the sensors. 

5. Put the container/s in a room that is at room temperature (near 20°C) for at least 4 hours

(the objective is to have the temperatures to equilibrate). 

6. As close as possible to a time when the sensor is recording a measurement, gently mix 

the water in the container and measure the water temperature with a NIST-certified 

thermometer; record the value on an accuracy check datasheet (see sample form in 

Appendix C). 

7. Put the container with the sensors in the refrigerator (near 0°C) for at least 4 hours. 

8. Remove the container from the refrigerator as close as possible to a time when the sensor

is recording a measurement; gently mix the water and measure the water temperature 

with a NIST thermometer; record the value on a datasheet (Appendix C). 

9. Repeat steps 5 through 8 several times to create multiple warming/cooling cycles. 

10. Remove the sensors from the container/s. 

Accuracy 

check

11. Download the data from the sensors onto a computer as soon as possible so that the 

sensor can be shut off to conserve battery life. 

12. Calculate the overall average temperature of each individual sensor for the entire 

calibration period as well as the maximums and minimums of each temperature cycle. 

Compare the mean temperature value to the group average. For the dates and times 

when measurements overlapped, compare the sensor temperature values to the NIST 

thermometer values. Calculate the average difference between these values. It should not 

exceed the accuracy quoted by the manufacturer of the temperature sensor, which should 

be ±0.5°C or, in some cases, ±0.2°C for sensors deployed at RMN sites. Sensors that 

have anomalous readings should be set aside and returned to the manufacturer for 

replacement. 

13. Record all accuracy check information on a data sheet (see sample form in Appendix C).

11
Whichever technique is used, differences in readings from the sensors and NIST-certified 

thermometers should not exceed the accuracy quoted by the manufacturer. For sensors deployed 

at RMN sites, that number is ±0.5°C or, in some cases, ±0.2°C. Sensors that have anomalous 

readings should be set aside for further testing or returned to the manufacturer for replacement. 

All accuracy check data should be recorded on a datasheet like the one shown in Appendix C. 

These records should be properly archived and stored in a place that can be easily accessed for 

future reference (these data will eventually be used for QA/QC procedures, as discussed in 

Section 2.6.1). Equipment needs for this procedure are listed in Table 5. 

Table 5. Equipment needs for the pre-deployment accuracy check

Task Supply list

Performing the 

calibration 

procedure 

• Temperature sensor/s

• National Institute of Standards and Technology (NIST) traceable or calibrated 

reference thermometer with an accuracy of ±0.2°C

• Field (e.g., red liquid) thermometers (optional) 

• Containers to hold the sensors 

• Water

• Refrigerator

• Clock or watch

Recording 

measurements

• Accuracy check data sheet (Appendix C)

• Computer that has the appropriate software for reading the temperature sensor

2.2.2. Sensor configuration and launch

Sensors can be programmed to start before or after the planned deployment time, or can be 

launched on site. Whatever the launch time, the exact time the sensor is correctly positioned 

should be recorded so that observations recorded before and after that time can later be removed 

during data processing (Section 2.6.2). Configure the sensors to record point temperature 

measurements in degrees Celsius at intervals of 30 minutes. If the sensor has insufficient 

memory capacity to record at 30-minute intervals for the deployment period, program the sensors 

to record point measurements every 60 or 90 minutes. Figure 6 suggests that 60-minute intervals 

are likely sufficient, although 30-minute intervals might more closely match other continuous 

data collection efforts, such as the hydrologic data being collected by the pressure transducers.

The following practices will make data processing and screening easier and more efficient:

• Set the sensors up so that they start recording on the hour (xx:00) or half hour (xx:30) 

• Set the units to degrees Celsius

• Set the air and water temperature sensors up so that they record at the same time

• Consider using military time (if this is an option) to avoid potential confusion with 

a.m./p.m. 

12
• Consider using local standard time (e.g., UTC-5 for sites in the Eastern Time zone) 

instead of daylight savings time. Regardless of which you choose, when doing accuracy 

checks, make sure any discrete measurements taken are consistent with this setting.

Considerations when choosing a sampling interval

Choosing a sampling interval is a balancing act. If long intervals are used, you could miss the 

maximum and minimum daily temperatures because they might occur only briefly within a day. 

Missing them would underestimate the warmest temperatures and overestimate the coldest 

temperatures. If too short an interval is used, too much memory could be used, requiring more site 

visits, data management, storage, and cleaning. 

Dunham et al. (2005) compared the amount of bias in daily summary metrics that is incurred by using 

different recording intervals. As shown in Figure 6, until intervals longer than 2 hours are used, bias

generally is not an issue. Sites with larger diel fluctuations have a greater probability of missing the 

true maximum than those with smaller diel fluctuations.

At RMN sites, the 30-minute interval will be reevaluated after the first or second year of data collection

to determine whether a longer interval (i.e., 60 or 90 minutes) can adequately capture the thermal 

regimes at sites.

Figure 6. Probability of underestimating the maximum daily temperature at least 1°C in 

relation to daily range of temperature and sampling interval (Dunham et al. 2005).

13
Record the configuration and launch information for each sensor on a datasheet, similar to the 

one shown in Appendix D. Include serial number, programmed deployment time, and recording 

interval. If the sensor has “sensor high, low, and multiple sampling” features and “wrap-aroundwhen-full, overwrite oldest data” functions, turn these functions off.

2.3. Deployment of Water Temperature Sensors 

Deploy at least one water temperature sensor at each RMN site. Place sensors in locations that 

can be safely accessed and waded by crew members during different flow conditions. If possible, 

avoid reaches with very high gradients (>7%) because sensor retention rates are inversely related 

with slope (Isaak et al. 2013). Prior to installing the sensors, obtain permission from all relevant 

parties (e.g., property owners if site access will involve crossing private property, the local 

Department of Public Works if the water temperature sensor will be attached to a bridge 

abutment). Try to minimize site impacts.

This document describes techniques that can be used to attach sensors to natural objects in 

streambeds at remote sites, and also covers installations in which sensors are attached to built 

structures like bridges. Provided the sensor is collecting data that are representative of the 

characteristics of the reach from which the biological data are being collected, the sensor need 

not be sited in the exact location from which biota are being collected.

2.3.1. Guidelines for placement within the stream

No simple, straightforward formula for selecting a location exists because each site is different. 

In general, however, areas of well-mixed water moving through runs and pools are preferable 

over riffles. Deploy sensors in locations with as many of the following characteristics as 

possible, prioritized in this order: 

• Representative of the characteristics of the 

reach from which the biological data were 

collected (e.g., not below additional warm 

or cold water sources) 

• Well-mixed horizontally and vertically 

• Of sufficient depth to keep the sensor 

submerged year round 

• Stable, accessible, and easy to relocate 

• Protected from physical impacts 

associated with high flow events (e.g., the 

downstream side of a large landmark rock 

or log) 

• Low human activity to reduce vandalism 

and accidental snagging

14

How do I know if the water is wellmixed?

In general, any moving water will be well

mixed. To verify this, take numerous 

instantaneous temperature measurements 

near the deployment location. If the stream 

can be easily waded, a simple crosssectional temperature survey, consisting of 

at least 10 measurements, can be done. If 

crews have access to a multi-probe meter, it 

is helpful to measure dissolved oxygen and 

conductivity as well, because variability in 

these measures could indicate sources of 

thermal variation (Dunham 2005). If these 

measures exhibit a high degree of 

variability, consider moving to a different 

deployment location. 
Do not select locations that:

• Are areas of high use, visibility, or fishing access 

• Have heavy beaver activity

• Have backwater pools, eddies, or standing water that might stratify during low flow 

conditions 

• Are influenced by localized warm or cool water sources, such as

o a tributary confluence

o an impoundment (including beaver ponds) 

o a lake outlet

o point-source discharges

o streamside wetland areas

o hot springs 

o groundwater seeps

When possible, deploy sensors approximately 6 inches (<0.15 meters) above the stream bottom 

(per Schuett-Hames et al. 1999). In some small, shallow streams you may have no choice but to 

place a sensor near the stream bottom to ensure that it remains submerged during low flows. If 

this happens, noting this on the field form is important because: 1) the temperature readings 

could be influenced by groundwater and subsurface flow (Stanford and Ward 1988, Baxter and 

Hauer 2000, Edwards 2001); and 2) sensors on or near the streambed are more susceptible to 

burial by moving substrates (sensors should never be intentionally buried).

If conditions permit, install sensors on the downstream side of the structure to which the sensor 

is being attached (e.g., a large rock or log). Doing so will help protect the sensor from high water 

velocities and associated substrate movement and transport of debris that commonly damage or 

dislodge sensors (Dunham et al. 2005). Ideally, the structure will also hide the sensor from 

potential vandals. 

2.3.2. Installation

If possible, install the sensor during low flow conditions to enable field personnel to check 

whether the water is well-mixed and of sufficient depth year round. Flow conditions can be 

determined by studying the hydrographs of local streams. In the next two sections, we briefly 

describe two installation methods: the underwater epoxy method (Isaak and Horan 2011, Isaak et 

al. 2013) and a method in which sensors are cabled to rebar or stable instream structures such as 

large rocks or boulders, woody debris, or roots (Mauger 2008, Ward 2011). Equipment needs for 

both techniques are listed in Appendix E. Site-specific conditions will dictate which installation 

technique is most appropriate. The best technique ultimately will be the one that is easiest to use 

and has the highest sensor retention rates over time. The pros and cons of each method are 

discussed in Sections 2.3.2.1 and 2.3.2.2. 

15
2.3.2.1. Underwater epoxy

The underwater epoxy method can be used in multiple environments provided a suitable anchor 

point is available, such as a large rock or cement structure (e.g., bridge support). Table 6

describes the step-by-step procedure for completing underwater epoxy installations. The first 

step is to select an appropriate rock or cement structure. The structure must have a relatively flat 

downstream attachment surface and must be in water that is moving and deep enough to remain 

submerged for the entire year. The best structures are those that not only remain immobile during 

floods, but also are wide and protrude well above the low flow water surface to provide an 

effective shield against moving rocks and debris. (Note: do not move rocks into the channel to 

serve as attachment sites—if you can lift the rock, high flows will certainly dislodge it, not to 

mention the safety risk associated with lifting large boulders). Ideally, on the downstream side of 

the attachment point, pockets of relatively calm water with smaller substrate sizes will be present 

(if large rocks and cobbles occur on the downstream side, similarly large substrates likely will 

move there again during the next flood, and these could dislodge or break the sensor). Cement 

bridge pilings at road crossings are also good attachment points for this protocol. Photos of good 

attachment points are shown in Figure 7. Research has shown that heat conduction through 

attachment structures like these does not bias temperature measurements if installations are done 

in keeping with the protocols described below (Isaak and Horan 2011). 

Table 6. Quick guide for doing underwater epoxy installations (Isaak et al. 2013) 

Task Procedure

Select 

attachment 

point 

1. The attachment point should have the following features:

• Is protruding a foot or more above the water surface at low flows (rocks of this size 

can be easily seen and relocated during subsequent field visits, and are large enough 

to prevent other rocks from sliding over them and potentially hitting the sensors 

during high flows) 

• Is wide enough to protect sensor from moving rocks/debris during floods 

• Has flat attachment site on downstream side and relatively deep water with flow

• Has small substrate on downstream side and 8 inches of space for shuttle attachment

Installation

2. Check sensor for blinking indicator light. Record sensor serial number and metal 

forestry tag number on field form (Appendix D). 

3. Put on gloves and use wire brush to clean surface of attachment site (approximately 6 

inches above stream bed). Place a few cobbles or suitably sized rocks near the sensor 

site to later lean against the attached sensor.

4. Moisten gloves and scoop out small amount (about quarter-size in diameter, 1/8 in 

thick) of white and black epoxy from each container, and mix together for at least 1 

minute. Apply epoxy to back of sensor (or PVC canister) and metal forestry tag.

5. Gently push and slightly twist sensor (or PVC solar shield holding the sensor) onto 

attachment site.

6. Lean a rock against the face of PVC to hold it in place while the epoxy sets and check 

attachment site with plastic viewing box. 

Monument 

7. Attach forestry tag on boulder directly above sensor (above water line).

8. Mark the site as a waypoint on GPS and record coordinates on data sheet 

(Appendix D). Take several photos of site, and record photo numbers on data sheet. 

16
17

Figure 7. Examples of large rocks (a, b) and cement bridge pilings (c, d) that provide good 

sensor attachment sites. Each site has a flat downstream attachment surface that is shielded 

during floods from bedload and debris. Arrows point to the solar shield containing a sensor; 

circles highlight metal forestry tags epoxied above the sensor to monument the site (photos 

from Isaak et al. 2013). 

After selecting an attachment point, use epoxy to attach the sensor to the structure, and lean a 

rock against the face of the PVC canister to hold it in place while the epoxy sets (Figure 8). Use 

of a specific underwater epoxy is critical to the success of this method. Isaak and Horan (2011) 

tested several types of epoxy and found that only Fox FX-764 epoxy provided durable cementlike attachments that worked well in field conditions. Installations with the Fox FX-764 epoxy 

work well in a wide range of temperatures (2 to 20°C), but the epoxy becomes less cohesive in 

water temperatures exceeding 20°C. Installations done in especially warm streams might need to 

be done when water temperatures are relatively cool to allow the epoxy to set (Isaak et al. 2013). 

Once the epoxy sets, it will hold the sensor across the full range of annual and daily water 

temperatures. 

If you are inexperienced with this technique, complete some practice runs in the laboratory first, 

and then perform your first field installations at a few easily accessible locations that can be 

checked after a few days. If a sensor needs to be reattached to a structure that has old Fox 

bonding agent on it, using a different attachment point is best if possible. 
18

Equipment needs for underwater epoxy 

installations are summarized in Table 7

and Figure 9. Additional details on 

underwater epoxy installations are 

available in Isaak et al. (2013) and in a 

YouTube training video (accessed 15 

June 2013): 

http://www.youtube.com/watch?v=

vaYaycwfmXs&feature=youtu.be

The epoxy can also be used to attach a 

metal forestry tag near the sensor 

location. This can make the sensor 

easier to relocate during subsequent 

site visits (Figure 9). The numbers on 

the tags can be used as unique site 

identifiers. This is useful for data 

organization, especially if different 

sensors are used at a site over time 

(Isaak and Horan 2013). 

Table 7. Equipment list for doing underwater epoxy installations (Isaak et al. 2013) 

Figure 8. Close-up of a PVC solar shield with a 

temperature sensor glued to a rock in a stream. The 

rocks propped against the front of the solar shield 

holds it in place while the epoxy sets during the first 

24 hours.

Task Supply list

Installation

• Temperature sensor

• Radiation shield (PVC canister, 1-1/2” with screw top, mid-section, base)

• Underwater epoxy (FX-764 Splash Zone Epoxy) 

• Jars for mixing the epoxy 

• Underwater viewing box 

• Lead weights, 1⁄4 oz 

• Neoprene, 3 mm 

• Rubber gloves 

• Plumber’s tape

• Wire brush 

• Zip ties, 4” 

• Metal mirror

Monument1

• Metal forestry tags

• Spray paint 

• GPS

• Camera

• Data sheet (similar to Appendix D)

1

Monumenting is discussed in Section 2.3.3.
Figure 9. Equipment needed to permanently install temperature sensors in streams using 

underwater epoxy. The equipment includes: (a) two-part FX-764 epoxy from Fox Industries, 

(b) PVC solar shield, (c) temperature sensor, (d) cable ties, (e) plumber’s tape, (f) rubber 

gloves, (g) plastic viewing box, (h) wire brush, and (i) metal forestry tree tag (Isaak and Horan 

2013).

Pros and cons of the underwater epoxy method are summarized below. 

Pros:

• It requires minimal effort and materials. 

• It provides durable installations that have been shown to withstand floods and associated 

bedload movement (based on field trials, 80–90% of sensors installed correctly remained 

in place after 1- and 2-year intervals [Isaak et al. 2013]). 

• Retention rates have been formally tested and documented in a wide variety of streams 

and are based on several years of field trials (Isaak et al. 2013).

• Once a sensor site is successfully established, it is easily maintained in years thereafter 

simply by replacing sensors in PVC housings that remain in place. 

19
Cons 

• Finding suitable attachment sites within appropriate macrohabitats (runs) might be 

difficult, particularly in smaller streams that lack large rocky substrates.

• The technique is used primarily with Onset Tidbit© v2 sensors. The design would have 

to be modified to accommodate larger sensors like the Onset Hobo© Water Temp Pro v2 

sensors. 

• Obtaining the epoxy might be difficult. 

2.3.2.2. Cabling the sensor to rebar or stable instream structures 

Sensors may be cabled to rebar or stable instream structures like large rocks or boulders, roots, or 

woody debris. If site conditions permit, attach the sensors to the downstream side of the instream 

structure, as this will shield the sensor from moving rocks or debris during floods. Use heavyduty (e.g., 120-lb tensile strength) cable ties or wire to attach the sensors to the structures. If 

conditions permit, attach the sensor at two points, as shown in Figure 10. If you think the 

structure might move during high flow events, consider cabling or chaining the structure to an 

object on the nearest bank (or to another stable instream structure). 

If a site lacks these types of stable 

instream structures and the stream 

bottom is such that a metal stake can 

be driven into it (e.g., no near-surface 

bedrock or consolidated sediments), 

the rebar method can be used. An 

appropriately sized piece of rebar

(generally 2–4 feet) is driven into the 

streambed, deep enough to stay in 

place during high stream flow events. 

The sensor and its protective housing 

are attached to the rebar via heavyduty cable ties or wire. 

If possible, use rebar that is bent as 

shown in Figure 11 (design provided 

by Christopher M. Harbourt, 

Principal Engineer, Waterborne 

Environmental, Inc. Champaign, IL.

www.waterborne-env.com). If one 

leg of the rebar is a little longer than 

the other, the installations will be easier because you can start the longer leg first and then pound 

the rest into place. Using bent rebar has several advantages. For one, it is more secure because 

the metal bar is anchored in two places. A second benefit is that it poses less safety risk for 

people wading through the stream because no sharp points protrude upward into the water 

column (Personal communication, Christopher Harbourt, May 2, 2014). 

Figure 10. If conditions permit, attach sensors in two 

places, using heavy-duty (e.g., 120-lb tensile strength) 

cable ties. This picture was provided by MDDNR 

Monitoring and Non-Tidal Assessment. 

20
Various techniques can be used to attach the sensor and 

its protective housing to the rebar. Some examples are 

shown in Figure 12 and Figure 13. Appendix F contains 

detailed descriptions of two additional installation 

techniques. One describes the cable/rebar method that is 

used in Cook Inlet salmon streams in Alaska (Mauger 

2008), and the second is a technique the Delaware River 

Basin Commission (DRBC) developed that uses a low 

profile concrete base. 

Figure 11. Using bent rebar for

rebar installations has several 

advantages. It is more secure 

because the metal bar is anchored 

in two places. It also poses less 

safety risk for people who are 

wading through the stream because 

no sharp points protrude upward 

into the water column. This design 

was provided by Christopher M. 

Harbourt, Principal Engineer, 

Waterborne Environmental, Inc. 

Champaign, IL. www.waterborneenv.com. Installations are easier if 

one leg is a little longer than the 

other because you can start the 

longer leg first and then pound the 

rest into place.

Figure 12. Example of how a cable and rebar 

installation is configured for large streams in 

Maryland. During the field installation, the cable is 

tightened so that the sensor sits within the PVC 

housing. Heavy-duty cable ties are then run 

through two of the side holes in the PVC housing to 

secure the sensor to the side of the PVC. This 

picture was provided by MDDNR Monitoring and 

Non-Tidal Assessment.

21
Figure 13. Example of a rebar installation 

in a small stream in Shenandoah National 

Park, VA. The sensor is located inside the 

PVC housing, which has several holes 

drilled into it to facilitate water 

circulation. Two additional holes are 

drilled into the PVC housing to serve as 

attachment points for the rebar. The 

housing slides over the rebar as shown in 

the picture. The housing is then secured 

to the rebar with a metal clamp. Hex 

head screws are preferred over flat heads 

because using a socket-end screwdriver is 

easier if you are working under water, 

especially if you are working by feel. In 

larger streams where flooding is more of 

a risk, consider using two metal clamps: 

one on the top and one on the bottom. 

That way, if the sensor becomes displaced, the housing will stay with the rebar, and an 

underwater metal detector can be used to help find the sensor. In larger streams, the rebar is 

driven deeper into the substrate than in the photo shown here. This lessens the chances of its 

catching on logs and other debris during high flow events and also poses less safety risk for 

people who are wading through the stream. This picture was provided by Craig Snyder, USGS

Survey (csnyder@usgs.gov).

Pros and cons of the cabling method are summarized below. 

Pros:

• Provides more flexibility in placement location than the underwater epoxy method. 

• If the rebar method is used and a high flow or other event occurs that causes the sensor to 

become displaced, you could use a metal detector to relocate the sensor. 

Cons 

• For year-round deployments in streams that experience annual high flow events, sensors 

might be more prone to being buried or dislodged by moving substrates than sensors 

installed using the underwater epoxy technique. 

• Retention rates are not as well documented as for the underwater epoxy method. 

2.3.3. Documentation

One of the most common reasons for the loss of temperature sensors is failure to relocate the 

sensor after initial field deployment (Dunham et al. 2005). Thus, accurately georeferencing each 

sensor is critical as is documenting sensor placement in a way that enables field personnel to 

22
relocate the sensor during subsequent visits. Table 8 contains a list of guidelines for documenting 

sensor locations. First, record global positioning system (GPS) coordinates (latitude and 

longitude) for the exact site at which each sensor is deployed, as well as the datum of the GPS. If 

you are unable to obtain GPS coordinates in the field, note the sensor location on an accurate 

map and determine the coordinates later. Although GPS coordinates are useful for getting close 

to the site, they are insufficient alone, so digital photos should also be taken at each site and 

archived in a centralized database for future use. Photographs are important for relocating the 

instruments, documenting any changes to the monitoring location during the course of the study, 

and showing the near-stream habitat of the location where the sensor is deployed. 

Table 8. Guidelines for documenting the installation

Task Procedure

Initial deployment

• Use GPS to georeference the site.

• Take photographs from different perspectives; at least one photo should have 

a visual marker pointing to the temperature sensor. Archive photos in a 

central database for future use.

• Make detailed hand-drawn maps with landmark references (e.g., unique rock, 

log, root, flagging, or tree), sensor locations, direction of stream flow, places 

to park, paths to the stream, and any other characteristics that might be 

appropriate, annotate photographs when viewing them later on a computer, 

or both. 

• Complete the field form.

• Take an instantaneous stream temperature at the location of the sensor with a 

NIST-calibrated field thermometer. Note: this measurement should be taken 

as close as possible to the time when the sensor will be recording a reading. 

Take the photos from different perspectives (e.g., upstream and downstream). Include at least 

one shot with a visual marker (e.g., someone pointing to the underwater location of the sensor). 

Later, when viewing these photos on a computer, annotate them with notes about landmark 

references (e.g., unique rock, log, root, flagging, tree), sensor locations, direction of stream flow, 

places to park, paths to the stream, and whatever else might be appropriate. Detailed hand-drawn 

maps like the one shown in Figure 14 (Ward 2011) are also helpful. Relocation success can also 

be improved by using metal forestry tags to enhance the visibility of the structures to which the 

sensors are attached (where suitable) (Figure 15). The use of signage at RMN sites is optional. If 

your agency has specific policies regarding signage, follow those protocols. Be aware, however, 

that using signs could increase the chance of vandalism.

23
Figure 14. Example of a hand-drawn map from a field form used by the Washington State 

Department of Ecology (taken from Ward 2011). 

Figure 15. Metal forestry tags can be attached to 

the downstream side of large rocks to monument 

sites and air in relocation of sensors (Isaak et al. 

2013).

Record all documentation information 

on a field form, like the sample form

shown in Appendix G. Field forms 

should include information on station 

number, waterbody name, date, time, 

crew members, driving directions, serial 

number of sensor/s, time of deployment, 

sensor installation technique, image 

numbers/file names for the photographs, 

and detailed descriptions of sensor 

placement. Accurately recording the 

time and date of deployment is very 

important, as this information will be 

used in the error screening procedure 

described in Section 2.7.2. 

24
If the stream can be easily waded, take an instantaneous stream temperature measurement with a 

NIST-calibrated thermometer at the location of the sensor. This measurement will be used for an 

accuracy check (Section 2.6.1). To minimize the chance of a faulty measurement, take the 

measurement as close as possible to the sensor and as close as possible to the time when the 

sensor is recording a measurement. Make sure sufficient time has passed to allow the NISTcalibrated field thermometer to stabilize before recording the measurement and note whether the 

time is standard or daylight savings time. Equipment needs for taking these measurements and 

for documenting sensors are summarized in Table 9. 

Table 9. Equipment list for documenting sites

Task Supply list

Georeferencing and 

monumenting 

• GPS

• Camera

• Map or gazetteer, or both

• Metal forestry tags

• Field form (similar to Appendix D, Figure 3.3-4)

Measuring 

temperature • NIST-calibrated field thermometer or multi-probe meter, or both

2.3.4. Common problems

As summarized in Dunham et al. (2005), the three most common problems that cause sensors to 

be damaged or lost are:

• failure to relocate the temperature sensor after initial field deployment 

• human tampering or vandalism; and 

• natural disturbances, such as flooding, substrate movement, and animal influences (e.g., 

trampling by livestock or wildlife, beaver pond construction) 

Tips for minimizing the chances of losing sensors are summarized in Table 10. If there are sites 

where problems such as vandalism are expected to occur, consider deploying more than one 

sensor so that one can serve as a back-up. If you are using metal cables, clamps or rebar for 

installations and the sensor becomes displaced, consider using an underwater metal detector to 

help relocate the sensor. 

25

Does ice affect the sensors?

Not if the sensors are properly installed and remain submerged during winter. Ice in a stream is 0°C, 

so it will not bias winter water temperature readings, which are also near 0°C when ice is present. If 

the sensor is securely attached to the downstream side of a large boulder or other protective structure, 

chunks of ice moving downstream will not affect it. 
Table 10. Tips for minimizing the chance of sensors being lost or damaged

Problem Tips for minimizing chance of damage or loss

Failure to relocate sensor

after initial deployment

Follow the documentation steps described in Section 2.3.3, which include:

• Georeferencing all sensors 

• Monumenting sites with metal forestry tags

• Taking photographs 

• Creating detailed maps and notes 

Disruption or vandalism 

from humans or livestock

• Do not put sensors in areas of high use, visibility, or fishing access

• Camouflage the sensors (this is generally the least expensive option, 

but could also make the data sensor more difficult to relocate)

• Secure the sensor in locked and signed housing that is relatively 

impervious to physical vandalism or disruption 

• Actively coordinate with ongoing research, monitoring, or management 

efforts in the study area, not only to minimize duplication of 

temperature sampling efforts, but also to minimize problems with 

unintentional interference

Natural disturbances 

• Where possible, install sensors on the downstream side of a large 

landmark rock or log, as this will protect the sensor from moving rocks 

or debris during floods 

• Do not site sensors in areas with known beaver activity

• House the sensor in a protective case

2.4. Deployment of Air Temperature Sensors 

Air temperature plays an important role in controlling stream temperature (Hill et al. 2013). As 

discussed in Section 2.1.4, unbiased air temperature measurements can be difficult to obtain. If 

the sensor is located in an open area with full sun, unless a mechanically aspirated radiation 

shield is used (which requires power to run a small fan), bias will be associated with the radiation 

shield. If the sensor is located in a shady area near a stream, air temperature will be affected by 

the distance from the water (the closer the sensor is to the stream, the more the water buffers the 

air temperature because energy goes into evaporating stream water rather than warming the 

ground and air). 

The objective at RMN sites is to measure streamside temperature. The streamside air temperature 

data will be used to gain a better understanding of the relationship between air and water 

temperature at each RMN site. These data will provide important insights about the 

responsiveness of stream temperatures to air temperatures and the differing vulnerabilities of 

streams to thermal change. To capture this relationship effectively, the location of the air 

temperature sensor in relation to the water temperature sensor must remain constant throughout 

the period of data collection. Although air temperature has a strong effect on stream temperature,

many other controls, such as groundwater discharge, affect stream temperature. Although these 

other controlling factors are of interest, due to resource limitations, only air temperature can be 

consistently collected at RMN sites at this time. 

26
At least one air temperature sensor should be deployed at each RMN site. If the riparian zone is 

forested (which is likely—most of the RMN sites are located in forested watersheds), mount the 

air temperature sensor to the tree that is: 1) nearest the water temperature sensor, and 2) large 

enough to support the radiation shield and sensor (ideally >12 inches (0.305 meters) in diameter). 

Trees generally make the best attachment points because they provide stability, some degree of 

shade, and can help hide the sensor from potential vandals. If a suitable tree is present, attach the 

radiation shield and sensor to its north side, out of direct sunlight, using the simple four-step 

process described in Appendix B. Outfitting the temperature sensors with radiation shields is 

critical so that sunlight does not strike the sensor and bias the temperature readings (Dunham et 

al. 2005, Isaak and Horan 2011) (Section 2.1.4). Do not rely on vegetation alone as the primary 

radiation shield. 

To be consistent with typical meteorological observations, air sensors should be placed at a 

height of 2 meters, or approximately 6 feet, off the ground. Because trees, vegetation, and the 

ground create radiation microenvironments, try to minimize the amount of other vegetation near 

the sensor. If the air temperature sensor is not waterproof, ensure that the radiation shield 

provides sufficient protection from the elements. 

If trees or other suitable, stable existing structures (e.g., fence posts) are absent, mount the 

radiation shield and air temperature sensor to a 10-foot piece of 1/2-inch diameter PVC pipe, 

which can be purchased at a local building supply store. Using a drill, create a 1/8-inch hole in 

the PVC pipe at a height of 2 meters above the ground. Next, insert a 12-inch piece of heavygauge steel wire (a metal coat hanger works well) through the hole. This metal wire can be 

inserted through one of the small corrugated tubes at the top of the solar radiation shield. Plastic 

zip ties can then be used to stabilize and secure the solar radiation shield to the PVC pipe. Then, 

pound a 3- to 4-foot piece of metal rebar into the ground to a depth of approximately 1-foot, and 

slide the PVC pipe onto the rebar. This method has limitations. For one, it has only been used 

experimentally and has not been extensively tested. Another is that sensors installed in the open 

are more likely to be vandalized, and may also be more prone to destruction by animals. 

Installations should be documented per the procedures outlined in Section 2.3.3. After 

installation and during subsequent site visits, instantaneous air temperature measurements should 

be taken with a NIST-calibrated thermometer at the location of the sensor, as close as possible to 

the time of the expected sensor recording. These data will later be used to check the accuracy of 

the sensor (Section 2.6.1). 

If an air temperature sensor cannot be installed at a site, compile daily air temperature 

observations from the nearest active weather station. Online resources like Utah State 

University’s Climate Database Server (http://climate.usurf.usu.edu/mapGUI/mapGUI.php) can 

be used to locate the nearest weather station and to obtain data. How well the weather station 

data approximate on-site conditions depends on factors such as distance between the site and 

weather station and differences in topography and weather patterns. Local surface air 

temperatures can vary substantially (5–10°C) from nearby weather stations in mountainous 

terrain. This is particularly true in valleys, where temperature can become decoupled from the 

free atmosphere as a result of cold air drainage and pooling (Holden et al. 2011). 

27
Obtaining data from the nearest weather station is of value even if an air temperature sensor is 

installed at a site. The data could be used for QA/QC purposes (e.g., a comparison of the two 

datasets that reveals differences in patterns could indicate that the on-site sensor is

malfunctioning). Or, if the comparison shows little difference between data sets, the weather 

station data could be used in place of the data from the on-site sensor. This would free up a 

temperature sensor for use elsewhere, which could be important if resources are limited. 

2.5. Maintenance/Mid-Deployment Checks and Data Offload

After equipment is installed at a RMN site, try to revisit the site within the first month to confirm

that the installation is holding properly and that the sensor remains fully submerged in flowing 

water. After these initial deployment checks, visit the sites as frequently as your schedule permits

to check the condition of the sensors, gather data for mid-deployment accuracy checks and 

offload data. More frequent site visits will help ensure the longevity of the sensors as well as data 

quality. At a minimum, try to visit the RMN sites annually, ideally during low flow conditions. 

To gather data for the mid-deployment accuracy checks, collect instantaneous stream 

temperature measurements near the sensor with a NIST-calibrated field thermometer. To 

minimize the chance of a faulty measurement, take the measurement as close as possible to the 

sensor and as close as possible to the time when the sensor is recording a measurement, make 

sure sufficient time has passed to allow the NIST-calibrated field thermometer to stabilize before 

recording the measurement and note on your field form whether the time is standard or daylight 

savings time.

A biofouling check can also be performed but is optional at RMN sites. To perform this check, 

remove the sensor and gently clean it (per manufacturer’s instructions) to remove any biofilm or 

sediment, then return the cleaned sensor to the stream. Note on your field form the time at which 

the “pre-cleaning” measurement was made and the time of the first “post cleaning” 

measurement. Compare the readings. 

If possible, bring a laptop (with the appropriate software) and base station or waterproof shuttle 

into the field so that the data can be offloaded onto the computer on-site. This allows field 

personnel to: 

• quickly screen the data for atypical results (if any readings are unusual, consider 

replacing the sensor or moving it to a different location, e.g., perhaps the sensor is 

coming out of the water during baseflow conditions) 

• check the battery life on certain types of sensors (batteries in some sensors should be 

replaced each year, while others, like the Onset TidbiT v2, last five years or longer under 

normal use) 

• back up the data (e.g., onto a flash drive) before clearing the sensor memory

Table 11 and Appendix G contain checklists for performing these maintenance/mid-deployment 

checks and data downloads. Note things that could affect the quality of your data, such as signs 

of physical damage, vandalism, or disturbance. Also ensure that the sensor is not buried by 

sediment and remove anything that could foul the sensor and bias the temperature readings (e.g.,

28
debris, aquatic vegetation, algae). Take photographs to document any changes to the monitoring 

location during the course of the study. 

Table 11. Checklists for performing maintenance/mid-deployment checks and data 

downloads

Task Procedure

Maintenance/ 

middeployment 

checks

• Check the security of the housing and deployment equipment and adjust if 

necessary. 

• Look for signs of physical damage, vandalism, or disturbance. 

• Ensure that the sensor is submerged. If it is not, move it to a location where it is 

covered by water and will remain so during periods of base-flow. 

• Ensure the sensor is not buried in sediment. If it is, remove the sediment and 

reinstall the sensor where it will not be buried during future high flow events. 

Note on the datasheet that the sensor was buried because temperature recordings 

are likely to be significantly biased toward cooler temperatures by hyporheic 

flows. In many cases, temperature recordings from buried sensors should be 

discarded because of high bias and because accurate adjustments are difficult to 

apply. 

• Remove anything that could bias the temperature readings (e.g., debris, aquatic 

vegetation, algae). Note: if sensors have protective housings with fine screens or 

small flow-through holes, they can be easily fouled in eutrophic systems with 

abundant periphyton or algal growth. 

• Take photos to document any changes to the monitoring location (particularly 

those that could influence readings).

• Take instantaneous stream temperature measurements at the location of the sensor 

with a NIST-calibrated field thermometer. Note: this measurement should be 

taken as close as possible to the time when the sensor will be recording a reading. 

• Record observations on the field form (like the one shown in Appendix G). 

• OPTIONAL: Biofouling check. Remove the sensor and gently clean it (per 

manufacturer’s instructions) to remove any biofilm or sediment, then return the 

cleaned sensor to the stream. Note on your field form the time the ‘pre-cleaning’ 

measurement was made and the time of the first ‘post cleaning’ measurement. 

Compare the readings.

Data offload

• Before connecting the sensor to the data offload device, gently wipe the sensor 

with a soft wet cloth or soft bristled brush to remove any biofilm or sediment that 

could affect its ability to connect.

• Attach the sensor to a base station or shuttle and then connect the data offload 

device to a computer with the appropriate software. 

• Once the connection is established, follow manufacturer’s downloading 

procedures. 

• Clear the sensor memory as necessary to ensure sufficient capacity for continued 

deployment.

Sensor retrieval

• If a sensor is removed from a site, before leaving the site, mark it with a 

temporary tag identifying the site, date, and time of retrieval.

• Be sure to record the exact times of deployment (in proper position) and 

recovery. This information is needed for trimming data after retrieval.

29
Table 11. Checklists for performing maintenance/mid-deployment checks and data 

downloads (continued)

Task Procedure

Data offload

• Before connecting the sensor to the data offload device, gently wipe the sensor 

with a soft wet cloth or soft bristled brush to remove any biofilm or sediment that 

could affect its ability to connect.

• Attach the sensor to a base station or shuttle and then connect the data offload 

device to a computer with the appropriate software. 

• Once the connection is established, follow manufacturer’s downloading 

procedures. 

• Clear the sensor memory as necessary to ensure sufficient capacity for continued 

deployment.

Sensor retrieval

• If a sensor is removed from a site, before leaving the site, mark it with a temporary 

tag identifying the site, date, and time of retrieval.

• Be sure to record the exact times of deployment (in proper position) and recovery. 

This information is needed for trimming data after retrieval.

To gather data for the mid-deployment accuracy checks, collect instantaneous stream 

temperature measurements near the sensor with a NIST-calibrated field thermometer. To 

minimize the chance of a faulty measurement, take the measurement as close as possible to the 

sensor and as close as possible to the time when the sensor is recording a measurement, make 

sure sufficient time has passed to allow the NIST-calibrated field thermometer to stabilize before 

recording the measurement and note on your field form whether the time is standard or daylight 

savings time.

A biofouling check can also be performed but is optional at RMN sites. To perform this check, 

remove the sensor and gently clean it (per manufacturer’s instructions) to remove any biofilm or 

sediment, then return the cleaned sensor to the stream. Note on your field form the time at which 

the “pre-cleaning” measurement was made and the time of the first “post cleaning” 

measurement. Compare the readings. 

If possible, bring a laptop (with the appropriate software) and base station or waterproof shuttle 

into the field so that the data can be offloaded onto the computer on-site. This allows field 

personnel to: 

• quickly screen the data for atypical results (if any readings are unusual, consider 

replacing the sensor or moving it to a different location, e.g., perhaps the sensor is 

coming out of the water during baseflow conditions) 

• check the battery life on certain types of sensors (batteries in some sensors should be 

replaced each year, while others, like the Onset TidbiT v2, last five years or longer under 

normal use) 

• back up the data (e.g., onto a flash drive) before clearing the sensor memory

30
If bringing a laptop into the field is impractical, offload the data onto a portable data storage 

device (like the Onset waterproof shuttle) and view it later when you have access to a computer. 

Data should be transferred from the data offload device to a computer as soon as possible. 

If the sensor is functioning properly and has sufficient battery life, it can be redeployed at the 

site. If the sensor is removed from the site, before leaving the site, mark the sensor with a 

temporary tag identifying the site, date, and time of retrieval, and replace it with another sensor

that has passed a pre-deployment accuracy check (Section 2.2.1). Accurately recording the time 

and date of retrieval is critical, as this information will be used in the error screening described in 

Section 2.7.2. When you replace a sensor, if the original one was not permanently attached to a 

structure, put the sensor as close as possible to the original location to minimize potential sources 

of variability in the long-term record. That comprehensive field notes be taken during every site 

visit is essential. Sample field forms can be found in Appendix G. Equipment needs for 

maintenance, mid-deployment checks, and data downloads are summarized in Table 12. 

2.6. Quality Assurance and Control

Perform QA/QC procedures after data are offloaded to verify the quality of the data and to check 

for potential errors. Document these procedures (e.g., on a form like the one shown in Appendix 

H). Any forms and other documentation should be organized, easily accessible, and archived in a 

way that allows for safe, long-term storage. The series of data cleaning steps described in Section 

2.6.2 can improve data quality, reduce the time and effort of data processing, and increase 

collaboration and comparability across projects, streams, and regions (Sowder and Steele 2012). 

Table 12. Equipment list for conducting maintenance/mid-deployment checks and data 

downloads

Task Supply list

Relocating sensor

• GPS

• Map, gazetteer, or both

• Annotated photos or hand-drawn map with landmark references (see 

Section 2.3.3) 

Documenting on-site

conditions 

• Camera

• Field form (similar to Appendix E)

Data offloads • Base station or portable shuttle

• Laptop (if practical) and data back-up device (e.g., flash drive)

Measuring temperature • NIST-calibrated field thermometer, multi-probe meter, or both

Back-up equipment (in 

case a sensor needs to be 

replaced)

• Calibrated replacement sensors and other necessary deployment 

equipment 

31
2.6.1. Mid- and post-deployment accuracy checks

After sensor data are downloaded, compare the instantaneous NIST-calibrated field thermometer 

measurements from the mid-deployment checks to the corresponding sensor readings. The sensor 

readings should not exceed the accuracy quoted by the manufacturer. If a sensor fails this check, 

repeat the procedure. If it fails a second time, flag the data with an appropriate data qualifier, and 

review the field notes to look for comments about situations that could cause the NIST-calibrated 

field thermometer measurement to be faulty (e.g., perhaps the crew could not take the 

measurement in close proximity to the temperature sensor due to high flow conditions, or used 

daylight savings time instead of standard time when recording the time of the measurement). If 

no issues with the NIST-calibrated field thermometer measurement are documented, consider 

replacing the sensor. After the sensors are retrieved and brought back to the office or laboratory, 

conduct a post-deployment accuracy check on each sensor, using one of the pre-deployment 

accuracy check procedures described in Section 2.2.1. 

2.6.2. Error screening

Erratic readings with temperature sensors can occur for a number of reasons, including: 

• they could become dewatered during low flow conditions 

• high flow events could bury them in sediment 

• high flow events could move them 

• they could become fouled from debris, aquatic vegetation, or algae 

• humans could cause interference

Therefore, a standard set of procedures should be performed to ensure the quality of the data and 

make necessary corrections. A series of error screening checks based on guidance from Dunham 

et al. (2005) and Sowder and Steel (2012) is described in Table 13, and Appendix H contains a 

data screening checklist. The first step involves removing observations recorded before and after 

the sensor is correctly positioned. This can be done via a visual inspection of data and by 

referencing field notes indicating the exact times of deployment and recovery. While reviewing 

the field notes, also look for comments about situations that could cause the sensor to record 

questionable readings (e.g., during a mid-deployment check, the sensor was found to be 

dewatered or buried in the sand) and flag those data accordingly.

Next, plot all temperature measurements versus date/time and visually check the data. Look for 

missing data and abnormalities, Consider plotting air and stream temperature on the same graph, 

as well as stream temperature and stage (depth) data (if available). Specific errors to watch for 

include missing data; a close correspondence between water and air temperature (this indicates 

that the stream sensor might have been out of the water); and diel fluxes with flat tops (this 

indicates that the sensor might have been buried in sediment). In addition, consider performing 

the following optional checks: graphically compare data across sites; graphically compare data 

across years (dramatically different data from one year indicates possible errors); graphically 

compare with data from the nearest active weather station (if appropriate). If discrepancies occur, 

use the plots to specify the time and duration of errors in the raw data files.

32
Table 13. Error screening procedure (Dunham et al. 2005, Sowder and Steel 2012, Personal 

communication, Michael Kashiwagi (MDDNR), April 17, 2014, Personal communication, 

Dustin Shull (PADEP), February 2, 2014)

Task Procedure

Remove pre- and 

post-deployment 

observations 

• Use field notes indicating the exact times of deployment and recovery to 

remove observations recorded before and after the sensor is correctly 

positioned in the stream channel. 

Visual checks

• Plot individual data points versus date/time to look for missing data and 

abnormalities 

• Graphically compare stream to air temperature (if available); a close 

correspondence between water and air temperature is a strong indication that 

the stream sensor was out of the water

• Optional: Graphically compare data across sites 

• Optional: Graphically compare data across years; when data from one year 

are dramatically different, data errors might be present 

• Optional: Graphically compare with stage data (if available)

Automated checks

• Calculate upper and lower 5th percentiles of the data

• Flag data points for potential errors if they:

o Exceed a thermal maximum of 25°C*

o Exceed a thermal minimum of −1°C*

o Exceed a daily change of 10°C*

o Exceed the upper 5th percentile of the overall distribution 

o Fall below the lower 5th percentile of the overall distribution

*These values should be adjusted to thermal limits appropriate for each location.

Additional checks are described in Table 13 and Appendix H. These include flagging data points 

for potential errors if they fall outside expected thermal limits (e.g., if water temperature 

measurements exceed a thermal maximum of 25°C or a daily change of 10°C). Thresholds 

should be adjusted to thermal limits that are appropriate for each site.

Various software applications can be used to help with the error screening checks, data 

management, and calculation of various summary statistics. The software purchased with the 

temperature sensors is likely to have some applications like this. Other options include free 

applications that can be downloaded from the U.S. Forest Service, Rocky Mountain Research 

Station stream temperature website (2014) 

(http://www.fs.fed.us/rm/boise/AWAE/projects/stream_temperature.shtml), which include a SAS 

temperature data processing macro and the Thermo Stat 3 software package (Jones and Schmidt 

2012). The Washington State Department of Ecology also has developed the Freshwater 

Monitoring Unit (FMU) Access® Data Logger Database, available upon request (Ward 2011). 

Errors should be addressed on a case-by-case basis. In general, three possible actions can be 

taken: 1) leave data as is; 2) apply correction factor; or 3) remove data. If you are inexperienced 

at addressing errors with continuous temperature data, consider seeking guidance from someone 

33
with more experience and consult references like Wagner et al. (2006). Table 14 provides a 

general summary of different types of problems that can occur (e.g., missing data, failed 

accuracy check) and recommended actions for addressing them. 

Table 14. General summary of different types of problems that can occur with continuous 

temperature data and recommended actions for addressing them

Problem Recommended action

Missing data Leave blank

Water temperature sensor was 

dewatered or buried in sediment for part 

of the deployment period

Use the plot to determine the period during which the problem 

occurred. Exclude these data from analyses. 

Recorded values are off by a constant, 

known amount (e.g., due to a 

calibration error)

Adjust each recorded value by a single, constant value within 

the correction period. 

A large amount of drift is present. It is 

unknown when and by how much the 

sensor was “off” (when drift occurs, the 

difference between discrete 

measurements and sensor readings 

increases over time)

The data should be removed. 

Discrepancy between sensor reading 

and discrete measurement taken during 

an accuracy or fouling check 

General rules:

• If the errors are smaller than the sensor accuracy quoted 

by the manufacturer and cannot be easily corrected (e.g., 

they are not off by a constant amount), leave the data as 

is.

• If the sensor fails a mid-deployment accuracy check, 

review field notes to see if any signs of disturbance or 

fouling were noted, and also look for notes about the 

quality of the QA/QC measurement (e.g., was the 

measurement taken by a National Institute of Standards 

and Technology [NIST] traceable or calibrated reference 

thermometer? Did environmental conditions prevent the 

measurement from being taken in close proximity to the 

sensor?). Also check whether the same time setting was 

used for both the sensor and discrete measurements 

(daylight savings time vs. standard time). Based on this 

information, use your best judgment to decide which 

action is most appropriate (leave as is, apply correction, or 

remove).

• If a sensor fails a post-retrieval accuracy check, repeat the 

procedure. If it fails a second time, use your best 

judgment to decide which action (leave as is, apply 

correction, or remove) is most appropriate. 

34
Corrections should not be made unless the cause(s) of error(s) can be validated or explained in 

the field notes or by comparison with information from nearby stations. Accurate field notes and 

accuracy check logs are essential in the data correction process. Any discrepancies should be 

documented in your data file and any actions you take should also be carefully documented. 

2.6.3. Record keeping

Even if the set of standardized procedures described in Section 2.6.2 is followed, the data 

cleaning process is inherently subjective, so both the original and the cleaned data files should be 

maintained and archived. Large amounts of stream temperature data will accumulate quickly so a 

central database should be developed and maintained from the initial stages of monitoring. Any 

changes you make to the data should be carefully documented, and all forms should be 

organized, easily accessible, and archived in a way that allows for safe, long-term storage. 

3. HYDROLOGY

The protocols in this section describe how to install and maintain pressure transducers and staff 

gages to measure continuous stage (depth). If additional measurements are taken, stage data can 

be converted to discharge (flow). Section 3.8 contains a brief description of how to collect the 

discharge measurements that are used to develop stage-discharge curves. Protocols and methods 

discussed in the following sections are based on those used by Massachusetts Division of 

Ecological Restorations River Instream Flow Stewards Program (RIFLS) (Chase 2005, Division 

of Ecological Restoration 2010), the USGS (Rantz et al. 1982), and the Washington Department 

of Ecology (Shedd 2011, Shedd and Springer 2012). 

3.1. Equipment

This section describes equipment used to collect stream stage data, using a combination of 

sensors for making continuous measurements and graduated staff gages for making discrete field 

measurements. Many different types of sensors can provide continuous monitoring and logging 

of stream stage. In this document, we focus on pressure transducers because most entities will be 

using these at RMN sites. 

3.1.1. Basic components

Two basic components are required to measure stream stage over time: 

• A submersible pressure transducer, which provides continuous monitoring and logging of 

water level (Section 3.1.4) 

• A staff gage, which is a graduated measuring instrument from which stage can be 

visually read (Section 3.1.3) 

Pressure transducers record absolute pressure (air pressure + water pressure), from which air 

pressure must be subtracted to yield water pressure. Software programs can then be used to 

convert water pressure to water level using the density of water. Because atmospheric pressure 

changes with weather and altitude, compensating for barometric variations is necessary; failure 

to account for these variations could result in errors of 0.6 m (2 ft) or more. 

35
Adjustments can be made in two ways: 1) if the transducer is vented, it has a vented cable that 

references and automatically corrects for atmospheric pressure; or 2) if the transducer is nonvented, barometric pressure readings must be obtained from a separate device that is located 

nearby on land, and after both sets of data are downloaded, software is used to correct the water 

level data for the barometric variations. Vented and non-vented transducers are discussed in 

more detail in Section 3.1.2. 

To access the data, a data offload device is required. This device can be a cable supplied with the 

transducer that connects directly from the data logger to a computer or a data shuttle that is 

purchased separately. The data shuttle used for the Onset temperature sensors (shown in Section 

2.1.3 and Figure 2) can also be used with Onset pressure transducers by attaching a different 

coupler. Additional software, specific to the pressure transducer, is necessary to view the data.

Additional equipment needed for installation can be found in Section 3.3 and Appendix I.

3.1.2. Considerations when choosing pressure transducers

Pressure transducers are of two main types: 

• Vented pressure transducers, which collect and automatically correct data for 

barometric pressure. These typically have transducers that are connected via vented 

cables to data loggers that are installed on land. 

o Pros:

The transducer does not need to be removed from the stream to download data (data 

are downloaded directly from the on-land logger). Data downloads are quick and 

convenient. You do not risk accidentally putting the transducer back at a different

elevation, which would necessitate the collection of new correction data. 

 Data are automatically corrected for barometric pressure, allowing for an 

immediate comparison of transducer data to gage data. This facilitates immediate 

detection and troubleshooting of any data quality issues in the field. 

o Cons:

 Maintenance of the vented cable can include changing desiccant and ensuring the 

cable is not damaged (e.g., ensuring animals did not chew cable). Extra 

precautions must be taken to ensure ice does not crimp vented cable in streams 

with ice cover. 

 Cable lengths are fixed, meaning that cables might not be long enough to allow 

the logger to be placed in a convenient location or might be so long that long 

loops must be stored in unwieldy coils. 

 The transducer can be subject to higher rates of vandalism compared to nonvented transducers due to visibility of the on-land data sensor and cable. 

36
• Non-vented pressure transducers, which do not automatically correct data for 

barometric pressure. This type of transducer typically has an internal data logger. 

o Pros: 

 Data loggers are internal and the transducer can be easier to hide in the stream 

than a vented transducer. 

 There is no vented cable to maintain. These transducers might be easier to use in 

streams with extended ice cover due to the lack of cable. 

o Cons: 

 A second, identical pressure transducer must be installed on land to collect 

barometric pressure for the correction. 

 Data must be corrected for barometric pressure post-download using the 

manufacturer-provided software. Data cannot be viewed in real time and unless 

data correction is done in the field, stage data cannot be viewed immediately.

 Data loggers are typically located inside the transducer and therefore must be 

removed from the stream to download data. If the transducer is not returned to the 

same location and elevation, new correction data will need to be collected.

Transducers at RMN sites should meet the 

following specifications: 

• Accuracy of ≤ 0.015 ft. Accuracy is 

a function of the operational range of 

the pressure transducer. As the range 

increases, the accuracy decreases. 

Manufacturers specify a full-scale 

accuracy for a given transducer; 

multiply this by the expected range of 

depths to be experienced by the 

transducer to assess whether the 

equipment will provide an 

appropriate level of accuracy. For 

example, a transducer with a full 

scale accuracy of ±0.1% should not 

be used over a range of depths 

greater than 15 feet. 

• Range to encompass the maximum 

expected range of stream stages for 

that location. A site visit prior to 

purchasing the transducer will help 

determine the expected range of 

flows. Because accuracy decreases as 

range increases, choose the smallest 

possible range. A depth range of less 

than 15 feet should be suitable at most RMN sites. 

If I am using a non-vented transducer, is it ok 

to use barometric pressure data from the 

nearest active weather station instead of 

deploying an on-land transducer?

Barometric pressure can vary over very small 

distances due to factors such as elevation and 

topography, so this should be evaluated on a siteby-site basis. The best way to evaluate how well 

the weather station data approximate on-site 

conditions is by collecting on-land transducer data 

for a year and comparing those data to the weather 

station data. If the two datasets are closely 

matched, the on-land transducer could be removed 

from the site. Additional considerations should be 

taken into account as well (e.g., Is the weather 

station expected to remain in operation during the 

period of deployment? What quality assurance and 

control measures are performed on the weather 

station data? At what rate are data collected, and 

do they need to be matched or interpolated to 

match with the in-stream transducer data?). 

Whichever data source is used, it is critical that the 

barometric pressure readings accurately represent 

on-site conditions because failure to account for 

pressure variations will result in erroneous water 

level measurements.

37
• Sufficient cable length to meet installation requirements (vented transducers only). 

Some transducers come with a standard 25-foot cable while others must be specified. A 

site visit prior to purchase will determine the length needed. If a site visit is not possible, 

a 50-foot cable is typically sufficient (see Section 3.3.2.2). 

Examples and pictures, respectively, of some commercially available pressure transducers are

found in Table 15 (on the next page) and Figure 16. Research your options carefully, and be sure 

to account for the fact that non-vented transducers might require purchasing a second transducer 

to measure barometric pressure on land. Also consider battery type (replaceable vs. nonreplaceable) and memory capacity. 

A) B) C)

D)

Figure 16. Numerous pressure transducers are commercially available. Some examples 

include: A) Onset Hobo© Water Level Data Logger; B) Global Waters Water level logger 

(WL16); C) INW Submersible Pressure & Temperature Smart Sensor (PT2X); and D) In-Situ 

Level TROLL.

3.1.3. Staff gage

Staff gages allow for instantaneous readings in the field, verification of transducer readings, and

correction of transducer drift. In addition, if securely installed, the staff gage can potentially 

provide an attachment point for the transducer. Gages at RMN sites should be USGS style 

(Type A) and marked every 0.02 feet (Figure 17).

38
Table 15. Examples of commercially available pressure transducers

Manufacturer and 

sensor model Type1

Ranges available 

(ft) that meet 

accuracy 

standards2

Accuracy3

Battery life 

(typical use) and 

replaceability

Logger 

memory

Approx. price4

($) Website

Onset Hobo© Water 

Level Data Logger 

(U20) 

Nonvented 0–13, 0–30 

±0.05% Full 

Scale (typical);

±0.1% Full scale 

(maximum)

5 years with 1 

minute or greater 

logging interval; 

factory replaceable

 Approx. 

21,700 records5

(64K bytes) 

$495 

(instream) + $495 

(on land) 

www.onsetcomp.com 

Global Waters 

Water Level Logger 

(WL16)

Vented 0–3, 0–15 

±0.1% Full Scale 

at constant 

temperature, 

±0.2% over 35°F 

to 70°F

Up to 1 year 

(depending on 

recording intervals); 

user replaceable 

(9V DC batteries)

Approx. 81,759 

records 

$989 (with 25 ft of 

cable) www.globalw.com 

INW Submersible 

Pressure & Temp. 

Smart Sensor with 

Datalogging (PT2X)

Vented 

or NonVented

Vented: 0–2.3, 0–

5.8, and 0–12 

Non-vented: 0–12 

±0.05% Full 

Scale (typical),

±0.1% Full scale 

(maximum)

18 months at 15-

minute interval; 

user replaceable

(AA batteries)

Available in 

130,000-, 

260,000-, and 

520,000-record 

versions

$1,095 (plus 

$2.35/ft cable) http://inwusa.com 

In-Situ Level TROLL 

500 & 700 Vented 0–11.5 

±0.05% Full 

Scale (at 15° C), 

±0.1% Full Scale 

(maximum)

10 years or 2 

million readings

130,000 

records (2.0 

MB)

$1,170 (plus cable 

if needed) www.in-situ.com 

1

Transducers can be either vented or non-vented (see Section 3.1.2 for more information). Non-vented transducers require an additional transducer to collect barometric 

pressure data. Some manufacturers sell both vented and non-vented versions of the same transducers. 2

Only ranges that meet accuracy standards are included in this table. Smaller depth ranges have higher accuracy.

3

Accuracy will vary based on selected depth range of transducer. Accuracy is calculated as a percentage of the “full scale” (depth range) of the transducer. Small depth 

ranges will have the highest accuracy. 4

As of January 2013 and subject to change; reduced prices might be available for bulk orders. 5

Readings can be taken at 15-minute intervals for approximately 112 days before the memory capacity is reached. 

39
3.1.4. Protective housing

Figure 17. Example of a USGS style staff gage 

(Type A) marked in 0.02-foot increments.

Instream pressure transducers at RMN sites 

should be encased in housings to protect them 

from currents, debris, ice, and other stressors. 

Inexpensive housings can be constructed from 

1.25-in or 1.5-in diameter Schedule 40 (or 

stronger) PVC pipe. Multiple 1/2-inch or larger 

holes should be drilled into the PVC to allow 

water to fluctuate at the same rate as in the 

stream (Figure 18). Factory-slotted PVC pipe 

with 0.010 slots, which is widely available for 

use in monitoring wells and piezometers, would 

also work well because it allows the free 

exchange of water while also keeping out fine 

sediments, debris, and biota. Some transducers, 

like the one shown in Figure 19, come in 

protective metal cases and do not need to be 

encased in an additional housing. In streams that 

are subject to extended ice cover, the entire 

length of the transducer and the vented cable 

can be encased to prevent potential damage. If 

vandalism is a concern, the housings can be 

painted black or camouflage to make them less 

visible. 

Figure 18. Example of a protective housing made of PVC pipe. This one is for a 

vented pressure transducer, which is secured inside the pipe with zip ties. 

40
3.2. Pre-Deployment

Prior to deploying the pressure transducer, check the 

transducer to ensure the batteries will last until the 

next field visit. If the sensor has previously been 

deployed, gently clean it (see transducer manual for 

cleaning methods) prior to redeployment. 

3.2.1. Accuracy Check

Figure 19. Some transducers come in a 

protective metal case and do not need 

to be encased in an additional housing.

Most transducers will be factory calibrated prior to 

being shipped. The accuracy of the transducers 

should be checked over time by comparing transducer 

data to staff gage data or by measuring the depth of 

water over the transducer with a stadia rod or other 

measuring device. Data should be compared over a 

variety of water depths to ensure the transducer is 

accurate over the full range of depths. Most entities

lack access to the type of facility that is needed to 

calibrate the transducers, so post-deployment field 

checks are typically used to check the accuracy of the 

transducers. 

Figure 20 illustrates how staff gage readings can be 

used to check the accuracy of the transducer data over 

time. The pressure transducer data are compared with 

the staff gage readings at similar times to determine 

the offset between the two. If transducer data do not 

correspond to staff gage data and water depth, the 

transducer might be fouled, it might need to be 

recalibrated, or it might need to be resurveyed (Section 3.5). Consult the transducer manual for 

details on how to calibrate transducers when recorded data are not accurate. If you recalibrate the 

transducer, record detailed notes on pre- and post-calibration values and changes that were made. 

If a transducer cannot be calibrated and appears to be recording inaccurate data, contact the 

manufacturer for further instructions, as it might need to be returned for service.

3.2.2. Sensor configuration and launch

Configure the pressure transducer and data logger to record temperature and pressure every 15 

minutes, starting on the hour. This is the same recording interval that is used at USGS gages. 

Some transducers allow the user to enter an offset value so that logged data are automatically 

adjusted to the staff gage. If using this option, record the details in the field notebook. Consult 

the transducer manual for specific details on configuration and launch. 

The following practices will make data processing and screening easier and more efficient:

• Set the transducers up so that they start recording on the hour (xx:00), half hour (xx:30), 

or quarter hour (xx:15 or xx:45).

41
Figure 20. Staff gage readings provide a quality check of transducer data. In this example, 

staff gage readings stopped matching transducer readings in November, indicating that the 

transducer or gage could have changed elevation.

• If you are using unvented pressure transducers, set both transducers up so that they 

record at the same time.

• Consider using military time (if this is an option) to avoid potential confusion with 

a.m./p.m.. 

• Consider using standard time (e.g., UTC-5 for sites in the Eastern Time zone) instead of 

daylight savings time. Regardless of which you choose, make sure that any discrete 

measurements taken for accuracy checks are consistent with this setting.

Bringing a computer into the field is helpful to launch the transducer and check the logged data 

once it is installed. Alternatively the transducer may be launched prior to deployment provided 

you note the date and time of actual deployment in the stream (this is important for data 

screening; see Section 3.7.2). 

42
3.3. Deployment of Instream Pressure Transducers

Installation of both staff gages and pressure transducers are covered in this section because they 

are typically installed during the same visit and pressure transducers are sometimes attached to 

the staff gages. During deployment, safety should always be a consideration, and transducers 

should only be placed in streams that can be safely accessed and waded by crew members. Install 

staff gages where they can safely be read at all stages. This might require that you install two 

sections of a staff gage in different locations (e.g., one in the low flow channel and one in the 

high flow channel) if the stream experiences a wide range of stages. Prior to installing the 

equipment, obtain permissions from all relevant parties. This often includes the local Department 

of Public Works (particularly for bridge installations), the local conservation commission (or 

equivalent), and abutting property owners if accessing sites will involve crossing private 

property. Field crews should make efforts to minimize site impacts. 

3.3.1. Selecting a location

Prior to gage and transducer installation, conduct a site reconnaissance survey to identify suitable 

stretches of river for installation. At some sites, natural streambed installations will be most 

appropriate, while at others, attaching equipment to built structures like bridges might be best. 

During the site visit, determine what type of installation is best so that appropriate equipment can 

be obtained prior to installation. If the transducer is collecting data that are representative of the 

characteristics of the reach from which the biological data are being collected, the transducer 

does not have to be located in the exact area where the biological data are being collected (e.g., 

perhaps the best attachment point for the transducer is a bridge or other built structure, and the 

biological sample is collected 200 meters upstream from the bridge). 

Key considerations for siting instream transducers are listed below. These considerations are 

similar to those for water temperature sensors (see Section 2.3.1). More detailed information on 

site selection and controls can be found in Rantz et al. (1982). 

• The water level data should be representative of the characteristics of the reach from 

which the biological data were collected. Note that for general monitoring purposes, the 

sensor need not be placed in the exact location where biological data are being collected. 

• Ensure that the site is not in the immediate vicinity of tributaries entering the river, and 

that no water is entering or exiting between the pressure transducer and the biological 

sampling site (e.g., through tributaries, pumping, or diversions). The goal is to minimize 

potential impacts from backwater during high flows (tributary downstream) or unevenly 

distributed streamflow across the channel (tributary upstream).

• The gaging equipment should be installed in a pool where turbulence is minimal to 

increase accuracy of gage and transducer readings. The pool should have a downstream 

control feature that allows for stable stage measurements and ensures that the equipment 

will be submerged during low flows (Figure 21, Rantz et al. 1982). Natural controls 

might include a downstream riffle, bedrock outcrop, or other stream feature that controls 

flow. Unnatural controls might include a bridge or culvert that is narrower than the 

stream channel and constricts flow. Note that the feature controlling the stage-discharge 

relationship can change at different flow levels; such changes will be reflected in the 

rating curve. 

43
• The site should not have extensive aquatic vegetation, beaver activity, or unstable 

streambeds and banks. These factors can change or result in unstable stage 

measurements. 

Figure 21. Examples of controls downstream of staff gages include A. riffle and B. culvert. 

3.3.2. Staff gage installation

Staff gages and pressure transducers are typically installed during the same site visit, and 

transducers are sometimes attached to the staff gages. Staff gages can be attached to a fixed 

object in the stream (e.g., bridge, boulder, or weir) or installed in the streambed (Figure 22). If 

suitable conditions are present and proper equipment is available, attaching gages to a bridge or 

other fixed structure is preferable, as this minimizes the chance that the gage will shift in high 

flows or in the presence of large debris. The streambed installation method works best in smaller, 

higher order streams that do not experience extreme high flows that could knock over the gage. 

A list of equipment needed for installation is in Table 16. 

Figure 22. Examples of gage installation techniques include A. streambed, B. fixed object – 

bridge wing wall, and C. fixed object – boulder.

44
Table 16. Equipment list for staff gage installation

Location Supply list

All • Staff gage

• Gage board

• Screws (stainless steel or brass)

• Screwdriver

• Assorted drill bits for wood 

• Level

• Stepladder (if installing more than one section of a staff gage)

• Datasheets and field notebook

• Survey equipment (auto level or laser level and stadia rod, paint 

marker or nails for marking benchmarks)

Fixed Object –

additional items

• Concrete wedge anchor and nuts (stainless steel or galvanized)

• Hammer or rotary drill 

• Concrete drill bit

• Hammer 

Streambed –

additional items

• Galvanized or stainless steel pole with cap

• Galvanized or stainless steel conduit straps

• Pole driver or sledge hammer

• Pry bar

Gages are typically available in 3.33-foot sections; multiple gage sections can be combined to 

encompass the entire range of stages expected to occur in that section of the stream (additional 

sections can be added if the river tends to rise higher than expected). Stream gages should be 

attached to a board that is at least as high and wide as the gage and able to withstand being 

submerged in water (good materials include oak, plastic wood, or pressure-treated wood). Use 

screws and a level to attach the gage to the board. Care should be taken to level the combined 

board/gage before it is attached to the fixed object or pole. 

For fixed object installations, the gage and board are directly attached to a bridge or other 

permanent structure, using the following procedure: 

• Level the gage board on the fixed object and mark locations for concrete wedge anchors 

(Figure 23). Use concrete anchors on both sides of the board and at varying elevations to 

ensure the board’s stability. Two anchors are typically sufficient for a 3-foot gage and 

three for a 6-foot gage.

• Use a hammer drill or rotary hammer with a concrete drill bit to drill holes in the marked 

locations. 

• Pound concrete wedge anchors (bolts) into the holes using a hammer until they are 

secure. 

• Drill holes in the gage board for concrete wedge anchors. 

Place the board over the bolts and screw it into place using the nut. 

45
For streambed installations, the gage and board are attached to a pole that has been driven into 

the streambed, using the following 

procedure: 

• Use a pry bar to test the 

streambed in the pool for 

locations where the pole can be 

driven into the bed. 

• Drive a galvanized steel pipe 

with cap into the streambed 

using a pole (fencepost) driver 

or sledgehammer. Poles of 6 

feet and 9 feet are generally 

sufficient for 3.33-foot and 

6.66-foot gages, respectively. 

The pole should be driven into 

the streambed at least 3 feet or 

until it is very stable and 

unlikely to be knocked over in high flows. The pole should be as straight as possible so 

that when the board and gage are attached, they can be leveled. A step ladder can be 

helpful for driving the pole. 

• Attach the combined board/gage to the pole using galvanized or stainless steel conduit 

straps (use at least two for a 3.33-foot gage). The board should be parallel to the flow 

and, if possible, positioned so that it can be read from the stream banks. 

Figure 23. Example of a 0.5-inch by 3.75-inch wedge 

anchor with bolt and washer.

If a tree is nearby on the stream bank, a metal bracket or brace can be attached from the gage to 

the tree to increase stability. 

3.3.3. Pressure transducer installations

This document describes two installation techniques for pressure transducers: the fixed object 

method, in which the transducer is attached vertically to the staff gage board or to an object like 

a bridge, boulder, or weir; and the streambed method, in which the transducer is laid horizontally 

on the streambed and is held in place by rebar and rocks. Site-specific conditions dictate which 

technique is most appropriate. 

3.3.3.1. Fixed object

With the fixed object installation, the pressure transducer is attached vertically to the staff gage 

board or to an object like a bridge or boulder. Before the pressure transducer can be attached to 

the fixed object, it must be enclosed in a protective housing (Section 3.1.4). For vented 

transducers, which do not need to be removed from the stream to download data, the housing 

should be cut to a length at least slightly longer than the transducer. If PVC pipe is used, attach 

the transducer to the housing with heavy-duty zip ties to ensure it does not move (Figure 24). Do 

not leave slack in the zip ties. If the unit can move, it can wear through the zip tie. 

46
Figure 24. Non-vented pressure transducer installation. A. Non-stretch cable is attached to 

the transducer, B. A loop is made at the non-transducer end of the cable, C. A cable with 

transducer is suspended over the bolt from the top of the PVC pipe.

Non-vented pressure transducers typically should be removed from the stream to download data. 

To facilitate data removal and downloading during high water periods, install the transducer into 

a PVC pipe as follows: 

• Use a PVC pipe that is approximately the same height as the gage board.

• Attach a non-stretch cable or rope (e.g., coated stainless steel cable) to the transducer and 

make a loop at the non-transducer end (Figure 24). The cable should be long enough that 

the transducer will always be under water but not so long that it will come into contact 

with the streambed. 

• Place the looped cable over a long bolt with a wing nut that runs through the top of the 

PVC (Figure 24). Clearly mark the holes for the bolt so that the transducer is placed back 

at the same elevation every time it is removed.

Once the pressure transducer has been installed in the protective housing, the transducer/housing 

can be attached vertically to the staff gage board (Figure 25), a bridge abutment, or fixed object, 

or horizontally to rebar or other pipe in the stream bed. An equipment list for installations is

found in Table 17. 

47
Figure 25. Non-vented (left) and vented (right) pressure transducers attached to staff gage 

board using conduit hangars.

Table 17. Equipment list for transducer installation

Location Supply list

All (continued) 

• PVC pipe for transducer (drilled with 1/2-in or larger holes)

• PVC pipe for data logger or barometric pressure logger

• Galvanized or stainless steel conduit straps, hangars, and hose clamps 

• Zip ties/cable ties

• Screws (stainless steel or brass)

• Screwdriver

• Drill

• Assorted drill bits for wood and PVC 

• Level

• Datasheets and field notebook

• Survey equipment (see Section 3.3.5)

48
Table 17. Equipment list for transducer installation (continued)

Location Supply list

If using a non-vented transducer, you also need:

• Non-stretch cable or wire

• Wire rope clamps

• Long bolt and wing nut 

• Extra-long PVC (should extend out of water in high flows) 

• Solar shield (if using barometric logger for air temperature data, see 

Appendix B for instructions)

• PVC with caps for barometric transducer

If using a vented transducer, you also need: 

• Garden staples 

• PVC pipe for data logger 

• PVC cap or locking well cap 

• Stainless steel conduit straps

• Long lag screws

• Wire cable

• Replacement desiccant (if necessary)

Fixed object – 

additional items 

• Hammer or rotary drill 

• Concrete drill bit

• Concrete wedge anchor and nuts (stainless steel or galvanized)

• Hammer

To install the transducer/housing on a staff gage board: 

• Place the PVC pipe with transducer on the downstream side of the board directly next to 

the galvanized steel pole, or whichever side is the least turbulent. 

• Attach the PVC pipe to the board vertically using galvanized or stainless steel conduit 

straps or hangars. 

• Ensure that the PVC pipe and transducer are installed slightly above the streambed to 

reduce chances of fouling by fine sediments.

To install the transducer/housing on a fixed object (e.g., bridge abutment): 

• Install the transducer close to the staff gage so that stage changes are comparable. 

• Use concrete anchors and conduit straps, hangars, or hose clamps to attach the PVC 

vertically to a bridge or boulder. 

• Ensure that the PVC pipe and transducer are installed slightly above the streambed to 

reduce chances of fouling by fine sediments.

49
3.3.3.2. Streambed/rebar

With the streambed installation, the transducer is laid horizontally on the streambed and is held 

in place by rebar and rocks (Figure 26). Compared to the fixed object method, transducers are 

more prone to moving or being swept away during high flows, and ensuring that transducers are 

returned to the exact same location after being removed for data downloads can be more 

difficult. 

Figure 26. Examples of streambed installations of pressure transducers using rebar.

Streambed installations require rebar stakes and a sledgehammer in addition to the equipment 

listed in Table 16. Installation instructions are as follows:

• Find a pool location close to the staff gage and protected from turbulence and debris 

(behind a large rock is ideal). 

• Drive two rebar stakes into the ground (spaced apart slightly less than the length of the 

PVC housing). 

• Use cable ties or steel hose clamps to attach the PVC to the rebar in a relatively 

horizontal position. 

• For added stability, pin the PVC pipe between the rebar and the rock, or place large rocks 

over the PVC pipe, or do both. 

• Ensure that the PVC pipe and transducer are installed slightly above the streambed to 

reduce chances of fouling by fine sediments.

50
3.4. Deployment of On-Land Components

Both vented and non-vented transducers have components that must be installed on land. Vented 

transducers are typically connected to data loggers on land via a vented cable. When using nonvented transducers, a separate, identical transducer must be deployed on land to measure 

barometric pressure. This section describes a general installation approach for both components 

and concludes with specific considerations for data loggers and for barometric pressure sensors. 

Both devices should be located well above where high flows or the snow pack will reach, but not 

so high that they are inaccessible for data downloads. Trees are generally the most suitable

attachment points for these devices. If no trees are present, install a stainless steel pole (with a 

cap) and attach the data logger to it. Use the same type of pole used for the streambed staff gage 

installations. Hide the devices from view to reduce the chance of vandalism.

The devices should be encased in a PVC pipe. The device may sit on the bottom of the pipe or be 

suspended on a wire or cable. If the data logger is not supported by the PVC pipe, suspend it on a 

wire or cable so no pressure is placed on the vented cable. Leave enough slack in the data logger 

cable to allow the logger to be lifted slightly out of the PVC pipe to download data.

Installation instructions are as follows:

• Attach a PVC pipe to a fixed object on the bank. The pipe can be attached to a tree with 

U-shaped conduit straps and long screws or zip ties (Figure 27). Adjust the length of the 

pipe to adequately cover the device with some extra room. 

Figure 27. Vented transducer data logger installation. The transducer is attached to the 

tree with stainless steel conduit straps. 

51
• Place the device inside the PVC pipe. 

• Place a PVC cap or a locking well cap on top of the PVC pipe to protect the equipment 

and discourage vandalism. 

Specific considerations for the data logger include: 

• For vented transducers with excess cable, coil the cable and zip tie it to the tree or PVC 

pipe. 

• Use garden staples (4-inch U-shaped steel staples), rocks, and leaf litter to hide the data 

logger cable. For extra protection, the cable can be encased in a PVC pipe.

Specific considerations for the barometric pressure sensor include: 

• Place the device as close as possible to the instream pressure transducer. 

• The PVC housing should be drilled with holes to facilitate air flow (similar to those used 

to protect the instream pressure transducer [Figure 28]). 

Figure 28. Barometric pressure sensor installation for a non-vented transducer, A. 

without the PVC cap and B. with the PVC cap. Holes should be drilled into the bottom 

cup of the PVC housing. This prevents condensation and laterally blown rain and snow 

from filling the cup to a depth sufficient to inundate the ports through which the 

barometric pressure is compensated. Another option is to deploy the barometric 

pressure sensor upside down, so that the port tip is on top.

52
• Holes should also be drilled in the bottom of the PVC housing to prevent condensation 

and laterally blown rain and snow from filling the cup to a depth sufficient to inundate 

the ports through which the barometric pressure is compensated. If this occurs, the 

“barometric pressure” becomes barometric pressure plus a small amount of pressure due 

to this accumulated water, and the data cannot be used. This issue can also be addressed 

by deploying the barometric pressure sensor upside down, so that the port tip is on top. 

3.5. Elevation Surveys and Documentation

After the installation is complete, georeference and document the pressure transducer location in 

a way that enables field personnel to relocate the sensor during subsequent visits. Take 

photographs from different perspectives (e.g., upstream and downstream); photos are important 

for relocating the transducers and documenting changes to the monitoring location during the 

course of the study. Record all documentation information on a field form that includes 

information such as station number, waterbody name, date, time, crew members, driving 

directions, serial number/s of transducer/s, time of deployment, transducer installation technique, 

image numbers/file names for the photographs, and detailed descriptions of transducer

placement. Be sure to record the time and date of deployment accurately, as this information will 

be used in the error screening procedure described in Section 3.7.2. 

In addition, survey the elevation of the staff gage and pressure transducer to establish a reference 

point for the gage and transducer. This allows for monitoring of changes in the location of the 

transducer, which is important because if the transducer moves, stage data will be affected and 

corrections will need to be applied. If possible, conduct elevation surveys at least once a year to 

identify if and when movement occurs. This is particularly important after high flow events and 

periods of extended ice cover. Steps for conducting elevation surveys using an auto level are 

summarized in Table 18, and Table 19 contains a list of equipment needs. For additional 

information on surveying techniques see Harrelson et al. 1994.

Table 18. Quick guide for elevation surveys of staff gages and transducers using an auto level

Procedure

1. Set up tripod and auto level in location where you can view benchmark and all survey points. 

Level auto level by centering the level bubble using the foot screws. 

2. Have person hold stadia rod on top of benchmark. Rod must be level. 

3. Read elevation at which crosshairs in auto level cross the stadia rod.

4. Record this elevation as the starting backsite (B.S.). 

5. Have person hold stadia rod on survey point #1. Rod must be level. 

6. Read elevation at which crosshairs in auto level cross the stadia rod.

7. Record this elevation as the foresite (F.S.).

8. Repeat steps 6 to 8 for additional survey points (including the top of the staff gage and 

transducer).

9. Have person hold stadia rod on top of benchmark. Rod must be level. 

10. Read elevation at which crosshairs in auto level cross the stadia rod and record as final B.S.

11. If final B.S. does not match starting B.S. (within 0.01 ft), repeat the entire survey.

53
Perform the elevation survey on the day of staff 

gage and transducer installation. Identify and 

establish a benchmark and one or two other 

permanent markers at the site. The benchmark 

will serve as the predominant reference point for 

the gage/transducer; the additional permanent 

marker(s) provide a backup in case the benchmark 

is destroyed and allows for a check of benchmark 

movement. Knowing the absolute elevation of the 

benchmark is unnecessary as the purpose is to 

detect changes in elevation of the equipment 

relative to the benchmark. The benchmark 

therefore can be given a relative elevation 

(e.g., 100 feet) as part of the calculations. Reliable 

permanent markers can be found on bridges and other permanent structures (e.g., a specific 

corner on a part of the bridge structure) (Figure 29); nails in trees are less stable but a good 

alternative in relatively secluded sites. Boulders should be used only if they are very unlikely to 

shift and if a clear point on the boulder can be identified and marked with survey paint. All 

permanent markers should be visible and accessible during all expected stream stages and 

vegetation covers. 

Table 19. Equipment list for elevation 

surveys

Supply list

• Auto level or laser level

• Tripod 

• Stadia rod

• Survey paint 

• Survey nails 

• Datasheet

Figure 29. Examples of auto level and tripod used for elevation survey (A) and permanent 

structure used as a benchmark (B). 

54
Once markers are established, sketch their location on the data sheet (see example in Figure 30), 

clearly documenting both markers and relevant site features that can be used to locate the 

markers in subsequent surveys. Take pictures of the benchmark with clear identifying features. 

Survey the benchmark, permanent marker(s), and gage and transducer elevations, repeating the 

survey of the benchmark after all other points (see Table 18). If the benchmark height is different 

at the end of the survey compared to the beginning, repeat the entire survey. For surveying the 

staff gage, hold the stadia rod on the top of the metal gage (not the board). For surveying the 

transducer, make clear notes of where the stadia rod was placed on the PVC pipe (e.g., top, river 

right, river left). Calculate the elevations of all points relative to the benchmark using the 

following equations: 

Height of instrument (H.I.) = Backsite (B.S.) + Elevation of benchmark (B.M.)

Elevation of survey point = H.I. – Foresite (F.S.),

where B.S. is the height of the stadia rod at the benchmark and F.S. is the height of the stadia rod 

at each survey point (e.g., permanent marker, top of gage, transducer housing) and the elevation 

of benchmark is the relative elevation (e.g., 100 feet). To calculate the actual elevation of the 

transducer, subtract the distance from the transducer housing (at the point where the stadia rod 

was placed) to the sensor face from the elevation of the transducer housing. 

After elevations of all survey points are calculated, compare beginning and end H.I. to ensure no 

movement of the auto level during the survey. Next, compare elevation of all survey points to 

previously surveyed elevations to determine if movement occurred.

3.6. Maintenance/Mid-Deployment Checks and Data Offload

After a transducer is installed at a site, try to revisit the site within the first month to confirm that 

the installation is holding properly. After these initial deployment checks, at a minimum, visit 

sites annually (e.g., in conjunction with the biological sampling events). More frequent visits are 

encouraged, however, particularly to check for movement of the staff gage and transducer after 

high flow events and periods of extended ice cover. More frequent site visits will help ensure the 

longevity of gaging stations and data quality. 

During site visits, field personnel should:

• Check the condition of the transducer and perform necessary maintenance.

• Take staff gage readings or measure the depth of water over the transducer with a stadia 

rod or other measuring device, ideally at different flow conditions, to check the accuracy 

of the transducer data. To minimize the chance of a faulty measurement, take the 

measurement as close as possible to the time that the pressure transducer is recording a 

measurement, and get as stable a reading as possible (if flows are fluctuating rapidly at 

the time of the measurement, note this on your field form and try to record the depth as 

accurately as possible). Be sure that no one is standing upstream during these 

measurements, as this will affect the readings.

• Offload data.

55
56

Figure 30. An example of a completed elevation survey form.
Typical maintenance issues include:

• Ensuring that the instream pressure transducer is submerged and not buried in sediment.

• Clearing leaf litter and debris that might pile up against the gage, transducer, and 

downstream control. At the beginning of a site visit, clear this material as it could impact 

gage height. Note the stage before and after debris clearing to check for any changes. 

Stage data may be corrected if changes are detected.

• Checking for transducer and staff gage movement after high flows and floods. The 

difference in elevation between the staff gage and the transducer can change if sediment 

accumulation or scour occur near the gage and transducer. If movement is detected, 

secure the equipment (if necessary) and resurvey. Note any differences in gage and 

transducer elevation in a field notebook along with the date and time. If a gage is 

constantly shifting, consider an alternative location.

• Checking for impacts from ice cover. Water temperature and stage data should be 

evaluated for potential impacts from ice cover and data should be flagged accordingly.

• Cleaning sediment or algae from the pressure transducers. These can cause fouling and 

inaccurate readings. Consult the transducer manual for specific instructions on cleaning 

and maintenance. 

• Cleaning the staff gage with a scrub brush, especially during the summer months, so that 

the gage can be accurately read. For especially dirty gages, baking soda or native sand (if 

available in situ) can help in cleaning the gage. Paint over any rust marks on the gage 

with enamel paint to improve durability.

• Checking the condition of desiccant packets (vented transducers only). These are needed 

to keep the vented cable dry. Different transducers use different types of packets, and the 

lifespan of these packets varies depending on site-specific conditions (e.g., how much 

moisture is present in the air). 

If possible, download data during each site visit. Frequent data downloads, as well as frequent 

stage measurements from the staff gage, will help in early identification of transducer drift. To 

download data, a computer and a cable or data shuttle (to connect the transducer to the computer) 

is typically needed in the field (see Figure 31). Prior to download, record the stage at the staff 

gage and note any factors that might have affected the data since the previous deployment. After 

download, spot-check the data for accuracy. If no cleaning or troubleshooting is necessary, relaunch the transducer following procedures outlined in Section 3.2.2. Each time data are 

downloaded, complete a form like the one shown in Figure 32.

Also check battery life. Batteries in some sensors need to be replaced each year, while others last 

5 years or longer under normal use. Plan for these replacements.

Record information from mid-deployment checks in a field notebook or on a field form. That 

good field notes be taken during every site visit is essential. Entries should include notes about 

the condition of the transducer, staff gage (or other water level) readings, and whether any

unusual measurements appeared during the data spot-check (if available). Taking photos during 

57
each site visit is also good practice, as this will help document changes to the monitoring 

location during the course of the study. 

Figure 31. Data download from vented transducer with external data logger on land using 

computer and cable (left) and non-vented transducer with internal data logger using 

computer and data shuttle (right).

Figure 32. Example of a transducer download field data sheet.

3.7. Quality Assurance and Control

Proper QA/QC is essential to collecting accurate long-term data. The procedures discussed in the 

following sections will help detect and correct for errors in transducer and stage data.

3.7.1. Accuracy checks

Pressure transducer readings can drift over time, which can result in deviation of transducer data 

from that observed at the staff gage. As mentioned in Section 3.2.1, making periodic staff gage 

readings to detect any shift or drift in the transducer data is important. The stage should be 

recorded every time the site is visited for a discharge measurement or data download. Ideally, 

gage readings should be done at least every month, if possible, to ensure a variety of stages are 

58
captured throughout the deployment period. Frequent gage readings facilitate error screening and 

early detection and correction of transducer problems that help minimize data loss. If this 

frequency is not possible due to the remoteness of the field site, local volunteers or other state 

agency collaborators could assist with gage readings. Local watershed groups or other 

organizations might be able to help to identify local volunteers. At the minimum, try to visit sites 

after large storm events, which could impact the transducer.

3.7.2. Error screening

Pressure transducers might record erroneous readings during deployment for a variety of reasons, 

including:

• they can become dewatered during low flow conditions

• high flow events can bury them in sediment

• high flow events could move them

• they might become fouled from debris, aquatic vegetation, or algae 

• humans might cause interference

• they could become encased in ice

• if moisture enters the cable of a vented transducer, it could result in erratic readings or 

readings of zero water depth

• if the cable of a vented transducer becomes kinked or plugged, it could result in the data 

not being corrected for barometric pressure

Because these errors may occur, data should be screened. A series of error screening checks is 

described in Table 20, and Appendix K contains a data screening checklist. Various software 

applications can be used to help with the error screening checks (e.g., Microsoft Excel, Aquatic 

Informatics’ AQUARIUS (http://aquaticinformatics.com/products), including software that is 

purchased with the transducers(s)).

The first step in the error screening process involves removing observations recorded before and 

after the transducer is correctly positioned. This can be done via a visual inspection of data and 

by referencing field notes indicating the exact times of deployment and recovery. While 

reviewing the field notes, also look for comments about situations that could cause the transducer 

to record questionable readings (e.g., during a mid-deployment check, the transducer was found 

to be buried in the sand) and flag those data accordingly.

Next, plot all of the measurements and visually check the data. Look for missing data, outliers 

and other abnormalities, Specific errors to watch for include: missing data; values of 0 (which 

could mean that the pressure transducer was dewatered, or in the case of vented transducers, 

could mean that moisture entered the cable); values flat-lining at 0°C/32°F (the stream pressure 

transducer is likely encased in ice); negative values (if unvented transducers are being used, this 

could indicate that the barometric pressure correction is off ); and outliers or rapidly fluctuating 

values (the stream pressure transducer could have moved (e.g., due to a high flow event or 

vandalism). Also consider performing the following additional checks: graphically compare data 

59
Table 20. General summary of different types of problems that can occur with pressure 

transducer data and recommended actions for addressing them

Problem Recommended action

Missing data Leave blank

Stream pressure transducer was 

dewatered or buried in sediment 

for part of the deployment period

Use the plot (and temperature data, if available) to determine the 

period during which the problem occurred. Exclude these data when 

calculating summary statistics.

Recorded values are off by a 

constant, known amount (e.g., 

due to a calibration error)

Adjust each recorded value by a single, constant value within the 

correction period. 

Drift is large and when and how 

much the sensor was ‘off’ cannot 

be determined (when drift occurs, 

the difference between staff gage 

or depth readings and pressure 

transducer readings increases over 

time)

The data should be removed. 

Discrepancy between pressure 

transducer reading and discrete 

measurement taken during a staff 

gage or depth check 

General rules:

• If the errors are smaller than the accuracy quoted by the 

manufacturer and cannot be easily corrected (e.g., they are not 

off by a constant amount), leave the data as is, and include the 

data in summary statistics calculations.

• If the transducer fails a staff gage or depth accuracy check, 

review field notes to see if any signs of disturbance or fouling 

were noted, and also look for notes about the quality of the gage 

measurement (Were flows fluctuating rapidly at the time of the 

measurement?). Also check whether the same time setting was 

used for both the transducer and gage or depth measurements 

(daylight savings time vs. standard time). Based on this 

information, use your best judgment to decide which action 

(leave as is, apply correction, or remove) is most appropriate.

A shift is detected and an 

elevation survey reveals that the 

stream pressure transducer has 

moved

Stage readings can be adjusted by adding or subtracting the difference 

in elevation. If the exact date of the elevation change is unknown, 

compare gage data to transducer data to observe any shifts. If no gage 

data for the time period are available, transducer data should be 

examined for any sudden shifts in stage. Changes in the elevation 

typically occur during high flows, so closely examine all data during 

these time periods. 

The sensitivity of the pressure 

transducer changes with stage 

(e.g., the transducer is less 

sensitive or accurate at high 

stages)

Sensitivity drift can be detected by graphing the difference between 

transducer and staff gage readings against the gage height and plotting 

a linear trend line through it. A strong correlation between the data 

sets and a positive or negative trend line as stage increases or 

decreases could indicate a sensitivity shift. Based on this information, 

use your best judgment to decide which action (leave as is, apply 

correction, or remove) is most appropriate.

60
across years (when data from one year are dramatically different, errors might be present); 

graphically compare with precipitation data from the nearest active weather station; and 

graphically compare with data from the nearest USGS stream gage, if appropriate. If 

discrepancies occur, use the plots to specify the time and duration of errors in the raw data files.

Additional checks (e.g., for accuracy and drift) are described in Table K1 and Appendix K. If 

you are inexperienced at addressing errors with continuous stage data, consider seeking guidance 

from someone with more experience and consult references like Wagner et al. (2006). Table 20

provides a general summary of different types of problems that can occur (e.g., missing data, 

failed accuracy check) and recommended actions for addressing them. Corrections should not be 

made unless the cause(s) of error(s) can be validated or explained in the field notes or by 

comparison with information from nearby stations. 

Any changes or corrections that are made to the data should be noted, and both the original and 

the “cleaned” data files should be maintained and backed up. Large amounts of data will 

accumulate quickly so a central database should be developed and maintained from the initial 

stages of monitoring. Also, all field forms should be organized, easily accessible, and archived in 

a way that allows for safe, long-term storage. Accurate field notes and accuracy check logs are 

essential in the data correction process.

3.8. Developing Stage-Discharge Rating Curves

The previous section describes how to install and maintain pressure transducers to measure 

continuous stage (depth). Taken alone, stage measurements yield some information about 

streamflow patterns, including the timing, frequency, and duration of high flows (McMahon et 

al. 2003, Roy et al. 2005). Stage data per se, however, do not provide quantitative information 

about the magnitude of streamflows or flow volume, which makes comparing data between 

streams difficult. Furthermore, the channel shape can change from year to year, such that a 

similar stage measured in a given location during two separate years could represent different 

flows. Thus, to assess patterns and changes in stream hydrology, converting stage measurements 

into streamflow is most useful. Different approaches are available for converting stage to 

discharge. The most common approach is to develop a stage-discharge rating curve, which we 

present here.

A rating curve enables the user to convert stage measurements to streamflow. To develop a 

rating curve, a series of discharge (streamflow) measurements is made at a variety of stages, 

covering as wide a range of flows as possible. In this section, we briefly describe how to take 

discharge measurements in wadeable streams. This involves measuring the depth and velocity of 

the water passing through several segments along a given cross-section of stream. Each 

measured velocity is multiplied by its contributing flow area; the resulting flows are summed 

across the cross-section to produce a total flow. A full treatment of this topic is beyond the scope 

of this document. For more detailed guidance consult Rantz et al. (1982), Chase (2005), or Shedd 

(2011). 

3.8.1. When to measure discharge

Five to ten discharge measurements should be made to establish a rating curve at a new site. To 

construct a rating curve that accurately predicts flow under most conditions, take measurements 

61
over as wide a range of flows as possible. After establishing a rating curve, measure discharge at 

least once annually, and if possible, also after large storms or any other potentially channeldisturbing activities, to verify or (if needed) update the curve (see Figure 33. for an example of a 

channel-disturbing activity). If new measurements are more than 15% off the rating curve, 

follow-up measurements should be made to identify whether a shift has occurred and, if 

necessary, to establish a new rating curve.

 

Figure 33. A culvert replacement downstream of a stream gage on Gulf Brook in Pepperell, 

MA caused enough of a channel change to necessitate a new rating curve.

3.8.2. Equipment

This section covers measuring discharge using current meters, which is generally the most lowcost approach (compared to using acoustic doppler-based instruments, for example). The basic 

equipment includes: 

• Current meters measure point velocity. Many different types are available, including 

mechanical meters (e.g., Price and Pygmy meters, which are vertical-axis meters) and 

electromagnetic meters (e.g., Hach/Marsh-McBirney). 

• Wading rods are used to measure water depth at verticals and to set the current meter at 

the appropriate depth. 

• A measuring tape and stakes are used to define the exact location of the cross section at 

which depth and velocity are measured. 

3.8.3. Site selection

Site selection is critical for making a good discharge measurement. An ideal cross section will 

have the following characteristics (see Figure 34 for examples):

• A relatively straight stream channel with defined edges and a fairly uniform shape 

• Limited vegetative growth, large cobbles, and boulders 

62
Figure 34. Examples of good cross-sections for making discharge measurements.

• No eddies, slack water, or turbulence 

• Depths greater than 0.5 feet and velocities greater than 0.5 feet per second

• Similar flow to that at the gaging station (e.g., no tributaries or drainpipes should be 

located between the cross section and the gaging station) 

Meeting all of these criteria is often not possible (neither cross-section depicted in Figure 34 is 

perfect). Some minor alterations of the streambed, such as removing excessive aquatic plants or 

large rocks, can significantly improve the quality of a cross section. Rocks can also be moved to 

create a more defined stream edge. All such changes must be made before starting 

measurements. The location of the “best” cross section will likely vary depending on flow 

conditions. Often a culvert or bridge meets many of the above criteria and provides a good 

location to measure flow. 

3.8.4. Measurements

Streamflow is calculated by summing individual discharge measurements at numerous segments 

of the cross section. A measuring tape (tagline) is stretched across the stream perpendicular to 

streamflow and anchored at both banks. Distance along the tagline, channel depth, and stream 

velocity are measured and recorded at a minimum of 20 points along the cross section. Be sure 

that no one is standing upstream during these measurements, as this will affect the flow readings.

Measurement points should be closer together in portions of the cross section where flow is more 

concentrated and depths are greatest, in order to ensure that no more than 5% of the total 

discharge passes through any single segment. Measurements may be farther apart where the flow 

is lowest and depths are shallowest (Figure 35). Include additional segments where velocity or 

bottom irregularities are the greatest. 

63
Figure 35. Layout of a channel cross-section for obtaining discharge data, using the velocityarea procedure.

The exact methodology for making velocity measurements is somewhat specific to the 

instrument being used. For more details refer to Rantz et al. (1982), Chase (2005), City of Salem 

(2007), or Shedd (2011), and to instrument manuals.

In addition to measuring streamflow, field personnel should also estimate the gage height of zero 

flow (GZF), which provides information about the low end of the rating curve. The GZF is the 

water level at the gage at which the stream would cease flowing. To find it, locate the low flow 

channel through the hydraulic control downstream of the sensor. Measure the depth of water at 

the lowest point in the control and subtract that depth from the stage to calculate the GZF. 

Measuring the GZF at each discharge measurement is best, but locating this point at lower flows

might be most practical and effective. 

3.8.5. Documentation

At the time of the discharge measurement, take photographs of the staff gage, upstream of the 

gage, and downstream of the gage. Detailed notes about the discharge measurements should 

include the following, as applicable: 

• Date, weather conditions, field team members

• Start and end times

• Stage at the beginning and end of discharge measurements

• Current meter check (e.g., spin tests for Pygmy/Price) 

• Equipment used 

• Whether the gage and transducer elevation were surveyed 

64
• Description of the cross section location and characteristics, description of any observed 

changes that may impact the rating curve or streamflow

• Edge of bank location

• Discharge measured (if calculated automatically by meter), or width, depth, and velocity 

for each measurement (if calculating discharge in the lab/office)

• Point of zero flow (PZF, if measured) and location of PZF measurement

Examples of discharge datasheets for different flow meters can be found in Appendix J.

3.8.6. Quality assurance and control

As with other parameters, careful attention to QA/QC procedures is necessary to ensure accuracy 

of discharge measurements. Some good resources for discharge QA/QC include Rantz et al. 

(1972), Chase (2005), and Shedd (2011). Some major points to keep in mind are as follows:

• Make duplicate measurements, ideally with a different person making each measurement. 

The measurements may be along the same or different cross-sections. The difference 

between the two measurements should be less than 15%. Be sure that no one is standing

upstream during these measurements, as this will affect the flow readings.

• Periodically check the accuracy of your measurements by making measurements that you 

can compare to a standard, such as a real-time USGS gage, or to those obtained by an 

experienced hydrographer from the USGS or another agency.

• Major, channel-disturbing events (e.g., floods, new culverts) can alter the rating curve. If 

a major event occurs and subsequent points are not aligned with the original rating curve, 

a new rating curve might need to be developed and used to convert stage to discharge for 

points following that event.

3.8.7. Making flow rating curves

The rating curve is produced by plotting instantaneous flow measurements and stage heights. 

They can also be plotted in a basic spreadsheet program such as Microsoft Excel, or using 

software designed to produce rating curves, such as Aquatic Informatics’ AQUARIUS

(http://aquaticinformatics.com/products). The curve can include one or more break-points to 

account for changes in channel morphology at different stages. When drawn on a log-log scale, 

the rating curve should be a straight line. If the rating curve does not cover the full range of the 

stage recorded, the curve can be extended to equal twice the highest or half the lowest 

measurement recorded. For more detail, see Kennedy (1984). An example of a rating curve is 

shown in Figure 36.

65
Figure 36. Example of regular (left) and log-log scale (right) rating curves created using 

Aquatic Informatics’ AQUARIUS software.

4. LITERATURE CITED

Baxter, C.V., and F.R. Hauer. 2000. Geomorphology, hyporheic exchange and selection of 

spawning habitat by bull trout (Salvelinus confluentus). Canadian Journal of Fisheries and 

Aquatic Sciences 57:1470–1481. 

Bilhimer, D. and A. Stohr. 2009. Standard Operating Procedures for continuous temperature 

monitoring of fresh water rivers and streams conducted in a Total Maximum Daily Load 

(TMDL) project for stream temperature, Version 2.3. Washington State Department of 

Ecology, Environmental Assessment Program. Available online: 

http://www.ecy.wa.gov/programs/eap/qa/docs/ECY_EAP_SOP_Cont_Temp_Monit_TM

DL_v2_3EAP044.pdf. 

Chase, R. 2005. Standard Operating Procedure: Streamflow Measurement. Massachusetts 

Department of Environmental Protection, Division of Watershed Management. CN 68.0. 

Division of Ecological Restoration. 2010. River Instream Flow Stewards (RIFLS) Quality 

Assurance Project Plan. Massachusetts Department of Fish and Game. (Available on-line 

soon). 

City of Salem, OR. 2007. Quality Assurance Project Plan: City of Salem Stormwater Services, 

Continuous Water Quality Monitoring Program. Available online: 

http://www.cityofsalem.net/Departments/PublicWorks/Operations/StormwaterServices/D

ocuments/qapp_and_sop_4-07.pdf. 

Danielson, T. 2006. Protocols for Measuring Continuous Water Temperature Using an Onset 

Data Logger. Report DEPLW0700. Maine Department of Environmental Protection. 

66
Division of Ecological Restoration. 2010. River Instream Flow Stewards (RIFLS) Quality 

Assurance Project Plan. Massachusetts Department of Fish and Game. 

Dunham, J., G. Chandler, B. Rieman, and D. Martin. 2005. Measuring stream temperature with 

digital data sensors: A user’s guide. Gen. Tech. Rep. RMRSGTR-150WWW. Fort 

Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research 

Station. 15 p. Available online: ttp://fresc.usgs.gov/products/papers/1431_Dunham.pdf.

Durance I., and S.J. Ormerod. 2007. Climate change effects on upland stream macroinvertebrates 

over a 25-year period. Global Change Biology 13:942–957.

Edwards RT. 2001. The hyporheic zone. Pages 399–429 in Naiman RJ, Bilby RE, editors. River 

ecology and management. New York: Springer.

Fulford, J.M., K.G. Thibodeaux, and W.R. Kaehrle. 1994. Comparison of Current Meters used 

for Stream Gaging. Proceedings of the Symposium on Fundamentals and Advancements 

in Hydraulic Measurements and Experimentation, Buffalo, NY. Available online: 

http://water.usgs.gov/osw/pubs/CompCM.pdf.

Gill, G.C. 1979. Development of a small rugged radiation shield for air temperature 

measurements on drifting buoys. Report to NOAA Data Buoy Office for Development 

Contract #01-7-038-827 (IF). Bay, St. Louis, MO.

Gordon, N.D., T.A. McMahon, B.L. Finlayson, C.J. Gippel, and R.J. Nathan. 2004. Stream 

hydrology: an introduction for ecologists. Second edition. John Wiley and Sons, 

Hoboken, NJ.

Harrelson, C.C., Rawlins, C. L. and J.P. Potyondy. 1994. Stream channel reference sites: an 

illustrated guide to field technique. Gen. Tech. Rep. RM-245. Fort Collins, CO: U.S. 

Department of Agriculture, Forest Service, Rocky Mountain Forest and Range 

Experiment Station. 61 p.

Hill, R.A., Hawkins, C.P., and D.M. Carlisle. 2013. Predicting thermal reference conditions for 

USA streams and rivers. Freshwater Science 32(1):39–55.

Holden, Z.A., Klene, A., Keefe, R., and G. Moisen. 2013. Design and evaluation of an 

inexpensive solar radiation shield for monitoring surface air temperatures. Agricultural 

and Forest Meteorology180:281-286.

Holden, Z.A., J. Abatzoglou, C. Luce, and L.S. Baggett. 2011. Empirical downscaling of 

minimum air temperature at very fine resolutions in complex terrain. Agricultural and 

Forest Meteorology 151(8):1066–1073.

Holden, Z. 2010. Temperature Sensor Installation Instructions. Available online:

http://www.fs.fed.us/rm/boise/AWAE/projects/stream_temp/blogs/06ThoughtsOn%20mo

nitoringAirTemperaturesInComplexForestedTerrain.pdf

67
Isaak, D. J., D.L. Horan, and S.P. Wollrab. 2013. A Simple Protocol Using Underwater Epoxy to 

Install Annual Temperature Monitoring Sites in Rivers and Streams. Gen. Tech. Rep. 

RMRS-GTR-314. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, 

Rocky Mountain Research Station. 21 p. Available online: 

http://www.treesearch.fs.fed.us/pubs/44251

Isaak, D. J., and D.L. Horan. 2011. An assessment of underwater epoxies for permanently 

installing temperature in mountain streams. North American Journal of Fisheries 

Management 31:134-137. Available online: http://www.treesearch.fs.fed.us/pubs/37476. 

Isaak, D.J., S. Wollrab, D. Horan, and G. Chandler. 2012. Climate change effects on stream and 

river temperatures across the northwest U.S. from 1980–2009 and implications for 

salmonid fishes. Climatic Change 113:499–524. Available online: 

http://www.treesearch.fs.fed.us/pubs/39783. 

Jackson, J.K., and L. Fureder. 2006. Long-term studies of freshwater macroinvertebrates – a 

review of the frequency, duration, and ecological significance. Freshwater Biology 

51:591-603. 

Jones, N.E., and B. Schmidt. 2012. ThermoStat Version 3.0: Tools for Analyzing Thermal 

Regimes. Ontario Ministry of Natural Resources, Aquatic Research and Development 

Section. Available online: http://people.trentu.ca/nicholasjones/thermostat.htm. 

Kennedy, E.J. 1984. Discharge Ratings at Gaging Stations. Techniques of Water Resource 

Investigations of the USGS, Book 3: Applications of Hydraulics, Chapter A10. Available 

online: http://pubs.er.usgs.gov/publication/twri03A10. 

Kennen, J.G., D.J. Sullivan, J.T. May, A.H. Bell, K.M. Beaulieu, and D.E. Rice. 2011. Temporal 

changes in aquatic-invertebrate and fish assemblages in streams of the north-central and 

northeastern U.S. Ecological Indicators 18:312–329. 

MDDNR (Maryland Department of Natural Resources). (nd). Quality Assurance Document for 

Temperature Monitoring. Draft Version 1.3. Available online: 

http://www.dnr.state.md.us/streams/pdfs/QA_TemperatureMonitoring.pdf. 

Mauger, S. 2008. Water temperature data sensor protocol for Cook Inlet salmon streams. Cook 

Inletkeeper, Homer, Alaska. 10 p. Available online: 

http://inletkeeper.org/resources/contents/water-temperature-data-sensor-protocol. 

Mazor, R.D., A.H. Purcell, and V.H. Resh. 2009. Long-term variability in benthic 

macroinvertebrate bioassessments: A 20-year study from two northern Californian 

streams. Environmental Management 43:1269–1286. 

McMahon, G., J.D. Bales, J.F. Coles, E.M.P. Giddings, and H. Zappia. 2003. Use of stage data to 

characterize hydrologic conditions in an urbanizing environment. Journal of the 

American Water Resources Association 39:1529–1536. 

68
Meyer J.L., D.L. Strayer, J.B. Wallace, S.L. Eggert, G.S. Helfman, and N.E. Leonard. 2007. The 

contribution of headwater streams to biodiversity in river networks. Journal of the 

American Water Resources Association 43:86–103.

Onset Computer Corporation. 2014. A Quick Temp Accuracy Check (Ice Bath) [webpage]. 

Accessed 8 August 2014. Available online: http://www.onsetcomp.com/support/technotes/quick-temp-accuracy-check-ice-bath.

Poff, N. L., J.D. Allan, M.B. Bain, J.R. Karr, K.L. Prestegaard, B.D. Richter, R.E. Sparks, and 

J.C. Stromberg. 1997. The natural flow regime: a paradigm for river conservation and 

restoration. BioScience 47(11):769-784.

Rantz, S.E. et al. 1982. Measurement and Computation of Streamflow, Volume I: Measurement 

of Stage and Discharge and Volume II: Computation of Discharge. USGS Water Supply 

Paper 2175. Available online: http://water.usgs.gov/pubs/wsp/wsp2175/.

Roy, A.H., M.C. Freeman, B.J. Freeman, S.J. Wenger, W.E. Ensign, and J.L. Meyer. 2005. 

Investigating hydrologic alteration as a mechanism of fish assemblage shifts in 

urbanizing streams. Journal of the North American Benthological Society 24:656-678.

Schuett-Hames, D., A.E. Pleus, E. Rashin, and J. Matthews. 1999. TFW Monitoring Program 

Method Manual for the Stream Temperature Survey. Washington State Department of 

Natural Resources and NW Indian Fisheries Commission publication #TFW-AM9-99-

005. 

Selker, J. S., L. Thévenaz, H. Huwald, A. Mallet, W. Luxemburg, N. van de Giesen, M. Stejskal, 

J. Zeman, M. Westhoff, and M. B. Parlange (2006), Distributed fiber-optic temperature 

sensing for hydrologic systems, Water Resources Research 42, W12202, 

doi:10.1029/2006WR005326.

Shedd, J. R. 2011. Standard Operating Procedure for Measuring and Calculating Stream 

Discharge. Washington State Department of Ecology, Environmental Assessment 

Program. Available online: http://www.ecy.wa.gov/programs/eap/quality.html.

Shedd, J.R., and C. Springer. 2012. Standard Operating Procedures for Correction of Continuous 

Stage Records Subject to Instrument Drift, Analysis of Instrument Drift, and Calculation 

of Potential Error in Continuous Stage Records. Washington State Department of 

Ecology, Environmental Assessment Program – EAP No. EAP082. Available at: 

http://www.ecy.wa.gov/programs/eap/qa/docs/ECY_EAP_SOP_CorrectionOfContinuous

StageRecords_v1_0EAP082.pdf.

Sowder, C., and E.A. Steel. 2012. A note on the collection and cleaning of water temperature 

data. Water 4:597–606.

Stanford J.A., and J.V. Ward. 1988. The hyporheic habitat of river ecosystems. Nature 335:64–

66.

69
Torgersen, C., et al. 2001. Airborne thermal remote sensing for water temperature assessment in 

rivers and streams, Remote Sensing Environment 76(3), 386–398, doi:10.1016/S0034-

4257(01)00186-9.

U.S. EPA (U.S. Environmental Protection Agency). 2014. Regional Monitoring Networks 

(Internal Review Draft). National Center for Environmental Assessment, Office of 

Research and Development, Washington, DC; EPA/600/R-14/xxx. Available from the 

National Technical Information Service, Springfield, VA, and online at 

http://www.epa.gov/ncea.

U.S. Forest Service, Rocky Mountain Research Station. 2014. Stream Temperature Modeling 

and Monitoring [webpage]. Accessed 8 August 2014. Available online: 

http://www.fs.fed.us/rm/boise/AWAE/projects/stream_temperature.shtml

Vannote, R.L., G.W. Minshall, K.W. Cummins, J.R. Sedell, and C.E. Cushing. 1980. The River 

Continuum Concept. Canadian Journal of Fisheries and Aquatic Sciences 37:130–137.

Wagner, R.J., R.W. Boulger, Jr., C.J. Oblinger, and B.A. Smith. 2006. Guidelines and standard 

procedures for continuous water-quality monitors—Station operation, record 

computation, and data reporting: U.S. Geological Survey Techniques and Methods 1–D3,

51p.+8attachments; accessed August 30, 2011, at http://pubs.water.usgs.gov/tm1d3.

Ward, W. 2003. Continuous Temperature Sampling Protocols for the Environmental Monitoring 

and Trends Section. Publication No. 03-03-052. Washington State Department of 

Ecology Environmental Assessment Program. Available online: 

https://fortress.wa.gov/ecy/publications/publications/0303052.pdf.

Ward, W. 2011. Standard Operating Procedures for Continuous Temperature Monitoring of 

Fresh Water Rivers and Streams, version 1. Washington State Department of Ecology 

Environmental Assessment Program. Available online: 

http://www.ecy.wa.gov/programs/eap/qa/docs/ECY_EAP_SOP_Cont_Temp_Mon_Ambi

ent_v1_0EAP080.pdf.

Wilde, F.D. 2006. Temperature (ver. 2.0): U.S. Geological Survey Techniques of WaterResources Investigations, book 9, chap. A6., sec. 6.1, March 2006, accessed September 6, 

2011, from http://pubs.water.usgs.gov/twri9A6/.

70
Appendix A _____________________________________________________________________________________________

How to construct PVC housings for water temperature

sensors with cable installations

A-1 
Housing Construction 

PVC housings are very simple to make, are inexpensive ($10-$15), provide 

total shade for the logger, protect the logger from moving debris, and provide 

for secure attachment with a cable.

The data logger is suspended in a PVC pipe that allows stream water to flow 

through but prevents the penetration of solar radiation. Black PVC provides 

more camouflage than white PVC for sites where vandalism is a concern. In 

clear water streams, white PVC is recommended because black PVC has a 

tendency to absorb heat from the daylight. 

Materials needed to assemble housing: 

2" Schedule 40 ABS pipe (1' length) 

2" DWV clean out plug 

(2) 2" DWV female adaptor 

(2) 3/8 " x 4" ZC eye bolt 

(1) 8" cable ties

Multipurpose cement

Assorted nuts and bolts

Drill

Using the multipurpose cement, attach the female adapters to each end of the 

PVC pipe. Drill a 3/8” hole for one eyebolt to go through a clean-out plug. 

Drill at least 20 holes in the PVC to allow water flow. Secure the eye bolt 

through the cleanout plug with a nut and bolt. Insert a cable tie through two 

drilled holes to suspend the data logger in the housing. Additional cable ties 

can be used to secure rocks in the bottom of the housing that might be needed 

to weigh it down. Screw the cleanout plugs into the female adapters. 

Reference: Mauger, S. 2008. Water temperature data sensor protocol for Cook 

Inlet salmon streams. Cook Inletkeeper, Homer, Alaska; 10 p. Available online 

at https://inletkeeper.org/resources/contents/water-temperature-data-sensorprotocol.

A-2 
Appendix B

_____________________________________________________________________________________________

How to make and install homemade radiation shields for

air temperature sensors

B-1 
Air Temperature Sensor Installation Instructions

Zack Holden; email: zaholden@fs.fed.us (406) 274.6766

Instructions for building the radiation shield can be found at: www.youtube.com/watch?v=LkVmJRsw5vs

STEP 1: Mount radiation shield cover

The radiation shield should be installed at a height of 6 feet on the north-facing side of a large (> 12 

inch diameter) tree. A coniferous tree that does not lose its leaves in winter is preferred. Bend and 

fold the triangular tabs of the radiation shield cover downward to create angled “wings”. Nail the 

cover to the tree using aluminum nails (FIGURE 1). Hammer nail until nail head touches plastic, or 

for trees with thin bark, bend the nail sideways against the plastic shield to hold the shield firmly 

against the tree. Make sure the nail goes through both the triangular tab and rectangular back 

cover. This will give the shield extra support. Note that the angle of the cover wings can be adjusted 

depending on the size of the tree. The cover should be approximately perpendicular to the bole of the 

tree (level to the ground) as shown in FIGURE 2. However, when mounted on smaller trees, the 

shield will naturally bend downward, point toward the ground, which is not a problem.

FIGURE 1 FIGURE 2

STEP 2: Record Logtag sensor ID number

FIGURE 3

Sensor ID: 9900301054

Each Logtag temperature sensor has a unique 10 digit ID 

number located just above the barcode sticker (FIGURE 3). 

Record the ID number and the GPS location on a 

datasheet (Lat /Long or UTM X/Y, include the DATUM).

STEP 3: Secure Logtag to the 2-plate shield

You will see two holes drilled into the top piece of the 2-plate shield. Using a 4 or 6 inch zip tie, insert 

the zip tie through the top piece, through the logtag hole, then back up through the top piece. Secure 

the zip tie. Make sure to close the zip tie AS TIGHTLY AS POSSIBLE. The top corner of the logtag must 

be pulled snugly against the top of the plastic cover. The opposing corner should hang down and 

touch the bottom piece of the 2-plate shield. It is critical to minimize directsurface contact between 

the sensor and the plastic shield pieces and to allow as much air flow as possible past the sensor.

B-2 
STEP 4: Hang shielded sensor beneath the cover

Using 8 inch zip ties, suspend the 2-plate shield (logtag sensor is now housed inside) from the large 

mounted radiation shield cover as follows: push the 8 inch zip ties through the pre-drilled holes in 

the top cover and loop them through the 6 inch zip ties that are holding the 2-plate shield together 

(FIGURE 4 and FIGURE 5).

FIGURE 4 FIGURE 5

STEP 4: Close and adjust radiation shield

Using an 8 inch zip tie, secure the front of the 2-plate shield to the front of the shield cover (FIGURE 

6) as follows: insert the zip tie through the top of the cover, downward through each of the two 

plates below, and then bring it back up and close the zip tie. It is important that there be adequate 

space between the 2 plates that surround the temperature sensor to allow air flow. Use your hands 

to create a gap between the two lower plates. Adjust as necessary, using the friction of the zip tie 

to maintain space between the 2 lower plates housing the air sensor. There should be 

approximately a 1.25 to 1.5 inch gap between the two plates when you’re finished. The shield 

should be approximately parallel with the ground and sit approximately 6 feet (or higher) off the 

ground. When completed, it should look like FIGURE 6.

FIGURE 6

B-3 
Appendix C _____________________________________________________________________________________________

Forms for temperature sensor accuracy checks

C-1
Table C1. Form for doing temperature sensor accuracy checks. The temperature sensors and field thermometers are checked against a NIST-certified 

thermometer.

# Initials Date Time

Temperature (°C)

NIST

Thermometer

Field 

Thermometer

Field 

Thermometer Sensor Sensor Sensor Sensor Sensor

S/N - S/N - S/N - S/N - S/N - S/N - S/N - S/N -

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

C-2
Table C2. Form for checking mean temperature sensor readings against mean temperature from a NIST-certified thermometer.

Technician:

Date/s of accuracy check:

Overall mean temperature (NIST-certified thermometer) (°C):

Sensor S/N

Mean 

Temperature 

(°C)

Difference from 

NIST-certified 

thermometer (°C)

Minimum 

Temperature 

(°C)

Maximum 

Temperature 

(°C)

Battery 

Level

(Pass/Fail)

Accuracy 

Check

(Pass/Fail)

Notes

C-3
Table C3. Form for checking temperature sensor readings against one another. 

Technician:

Date/s of accuracy check:

Overall mean temperature (all sensors) (°C):

Overall minimum temperature (all sensors) (°C):

Overall maximum temperature (all sensors) (°C):

Sensor S/N

Mean 

Temperature 

(°C)

Difference 

from 

overall 

mean (°C)

Minimum 

Temperature 

(°C)

Maximum 

Temperature 

(°C)

Notes

 

 

 

 

 

 

 

 

 

 

 

C-4
Appendix D 

_____________________________________________________________________________________________

Temperature sensor deployment and tracking forms 

(fill out one for each sensor)

D-1 
S/N:

Water or air: 

Programmed launch date & time: 

Deployment date and time: 

Expected retrieval date:

Battery type: 

Configuration 

Recording interval: 

Units:

Start time:

Station number:

Waterbody name: 

GPS coordinates for sensor 

Longitude (dec. degrees): 

Latitude (dec. degrees): 

Datum:

File names of photos: 

 

 

Installation technique (e.g., underwater epoxy, rebar): 

Description of location (e.g. type of structure it is attached to; type of habitat (riffle, run)) 

 

Hand-drawn map (and/or attach print out of annotated photo) 

D-2 
Task Date Time Technician Notes

Pre-deployment accuracy check 

Launch/start 

Deployment (in position) 

Mid-deployment accuracy check 

(in Notes, write down NISTcalibrated field thermometer 

reading; then compare this to the 

sensor reading)

 

 

 

 

 

 

 

Data download 

 

 

 

 

 

 

 

Sensor Retrieval 

Post-deployment accuracy check

Comments ____________________________________________________________________ 

_____________________________________________________________________________ 

_____________________________________________________________________________ 

D-3 
Appendix E 

_____________________________________________________________________________________________

Equipment lists for temperature sensor procedures

E-1 
These are equipment lists for various phases of deployment. These lists do NOT include health 

and safety equipment or personal gear like waders. 

Equipment needs for the pre-deployment accuracy check. 

Task Supplies List

Performing the 

accuracy check

• Temperature sensor/s

• National Institute of Standards and Technology (NIST) traceable 

or calibrated reference thermometer with an accuracy of ±0.2°C

• Field thermometers (optional)

• Containers to hold the sensors 

• Water

• Refrigerator

• Clock or watch

Recording 

measurements

• Accuracy check data sheet (see sample forms in Appendix C)

• Computer that has the appropriate software for reading the 

temperature sensor

Equipment list for doing underwater epoxy installations (Isaak et al. 2010). 

Task Supplies list

Underwater 

epoxy 

installation

• Temperature sensor

• Radiation shield (PVC canister, 1-1/2” with screw top, midsection and base) 

• Underwater epoxy (FX-764 Splash Zone Epoxy) 

• Jars for mixing the epoxy 

• Underwater viewing box 

• Lead weights, 1⁄4 oz 

• Neoprene, 3mm 

• Rubber gloves 

• Wire brush 

• Zip ties, 4” 

• Metal mirror

E-2 
Equipment list for doing cable installations (Mauger 2008, Ward 2011). 

Task Supplies list

Cable 

installation

• Temperature sensor

• Radiation shield (example in Appendix A)

• Cable or heavy duty cable ties (e.g., 120-lb tensile strength)

• Rebar (3/8 to 1/2", 2-4 ft lengths) 

• Rebar pounder (for custom design, see Ward 2011) 

• For more information, reference Ward 2011 and Mauger 

2008

Equipment list for documenting sites.

Task Supply list

Georeferencing 

& monumenting

• GPS

• Camera

• Map and/or gazetteer

• Metal forestry tags

• Field form (see sample form in Appendix D)

• Spray paint (optional)

Equipment list for conducting maintenance/mid-deployment checks and data downloads.

Task Supply list

Documenting 

on-siteconditions

• Camera

• Field form (see sample form in Appendix G) 

Data offloads • Base station or portable shuttle

• Laptop (if practical) & data back-up device (e.g., flash drive)

Measuring 

temperature for 

accuracy check

• NIST-calibrated field thermometer and/or multi-probe meter

• Field form (see sample form in Appendix G)

Measuring depth 

(optional) 

• Meter ruler or calibrated rod/pole (e.g., surveyor’s rod)

• Measuring tape

• Field form (see sample form in Appendix G)

Back-up 

equipment (in 

case a sensor 

needs to be 

replaced)

• Replacement sensors (that have passed accuracy and battery 

checks) and other necessary deployment equipment

E-3 
Literature Cited

Mauger, S. 2008. Water temperature data sensor protocol for Cook Inlet salmon streams. Cook 

Inletkeeper, Homer, Alaska. 10 p. Available online at

http://inletkeeper.org/resources/contents/water-temperature-data-sensor-protocol. 

Ward, W. 2011. Standard Operating Procedures for Continuous Temperature Monitoring of 

Fresh Water Rivers and Streams, version 1. Washington State Department of Ecology 

Environmental Assessment Program. Available online at

http://www.ecy.wa.gov/programs/eap/qa/docs/ECY_EAP_SOP_Cont_Temp_Mon_Ambient_v1

_0EAP080.pdf. 

E-4 
Appendix F 

_____________________________________________________________________________________________

Examples of alternate installation techniques

F-1 
Rebar Method (Mauger, 2008) 

This method is preferred for streams with moderate movement of the streambed during high 

flows. The protective case or PVC housing is attached by a cable to a rebar stake sunk 3 feet 

into the stream bed. 

Secure an eyebolt to the rebar (approximately 1 foot from an end) with hose clamps. Secure 

one end of the cable to the eyebolt with a wire rope clip. Secure the other end to the 

protective case or PVC housing using a wire rope clip. Use a stake pounder to sink the rebar 

3 feet into the stream bottom near a large rock or other landmark. 

Materials:

1/2" rebar (4' length)

3/8" x 4" ZC eyebolt (1) 

9/16 - 1 1/16 hose clamp (3) 

1/8" wire rope clip (2) 

1/8" RL uncoated cable (2’ length) 

Stake pounder 

Stream Bank-Secured Cable Method (Mauger, 2008) 

This method is preferred for streams with significant movement of the streambed during high 

flows. In this method, the logger in its protective case or PVC housing is secured to the 

stream bank vegetation using plastic-coated wire rope.

The logger is secured to the wire rope (1/8” to 3/8” diameter and 12 

feet long) using a wire rope clip. Upon deployment, the cable is

wrapped around a large tree, rocks, bridge supports, or other secure 

object within or on the stream bank. The logger is then placed within 

the stream channel. Large stream rocks can be placed on top of the 

cable near the logger to hold the logger in place within the stream. 

The cable should be hidden under bank vegetation to avoid

vandalism or accidental disturbance. Try to avoid locations where 

the cable will cross active fishing or wildlife trails.

Sand Bag Method (Mauger, 2008) 

This method is preferred for streams with minimal movement of the streambed during 

high flow events. Sturdy sand bags can be purchased at most hardware stores. Fill the 

bag on-site with any mineral material (large rocks, cobbles, or sand). Avoid organic 

material which is often buoyant. The logger, in its protective case or PVC housing, can 

be attached to the bag by weaving a cable tie through the mesh. The bag can be tied off 

with a rope to the stream bank for extra security. The rope should be hidden under bank 

vegetation to avoid vandalism or accidental disturbance. Try to avoid locations where 

the rope will cross active fishing or wildlife trails.

Delaware River Basin Commission (DRBC) Low Profile Concrete Base Technique

DRBC uses this technique for year-round deployment of conductivity, temperature, and dissolved 

oxygen sensors. Some of their sensors have been deployed for more than 2 years with minimal 

maintenance. Their general protocol is as follows:

F-2 
To make the concrete base, pour 40-lbs of mixed concrete into a saucer snow sled (the sled is 

used as a mold and can be reused). Add some metal to the concrete to provide mounting 

points for the protective shield. 

Using metal straps, mount the protective shield to the concrete base.

Attach the sensor to the protective shield with zip ties. The sensor is affixed to the side of 

the shield such that the sensor face is held in the vertical plane. This is consistent with the 

manufacturer’s recommendations and reduces build-up of silt or bubbles on the sensor 

face.

F-3 
When placing the unit in the water, orient the base in such a way that flowing water will encounter 

the sensor first. This should reduce any mild impacts to water chemistry from water flowing over 

the shield or base. The end of the shield that points upstream should protrude a little further than the 

downstream end. 

Data are downloaded and conductivity and temperature sensors are cleaned about once every 3 

weeks.

Manufacturer’s recommendations for pre- and post-deployment data adjustment are followed.

For more information, contact John Yagecic (John.Yagecic@drbc.state.nj.us) and Eric Wentz 

(Eric.Wentz@drbc.state.nj.us) from the DRBC.

F-4 
Appendix G 

_____________________________________________________________________________________________

Mid-deployment/maintenance check form 

(fill out one for each mid-deployment site visit; information for both the air and 

water temperature sensor at the site can be recorded on this form) 

G-1 
Date:

Time:

Technicians:

Data offload (yes/no):

Battery life:

Station Number: 

Waterbody Name:

Water temperature S/N:

Air temperature S/N:

Photo file names: 

MAINTENANCE CHECK

Are there any signs of physical damage, vandalism or disturbance? If yes, describe. 

_________________________________________________________________________

Is the water temperature sensor dewatered? If yes, describe. 

___________________________________________________________________ 

Is the water temperature sensor buried in sediment? If yes, describe.

___________________________________________________________________ 

Is there evidence of fouling (i.e. debris, aquatic vegetation, algae)? If yes, describe. 

____________________________________________________________________ 

ACCURACY CHECK 

Temperature measurements should be taken with a National Institute of Standards and 

Technology (NIST) traceable or calibrated reference thermometer. 

NIST traceable or calibrated reference thermometer S/N:

Equipment

Water Air

Time Temperature 

(°C) Time Temperature (°C)

Field 

Thermometer 

Sensor 

G-2 
Appendix H 

_____________________________________________________________________________________________

Post-retrieval QA/QC procedures for temperature sensor 

data

H-1 
This appendix is organized into five sections:

1. Record keeping and data storage 

2. Data evaluation

3. Application of data corrections 

4. QA/QC checklist form for temperature sensor data

5. References

H1 Record keeping and data storage

• Make sure you set up a good record keeping and data storage system. Large amounts 

of data will accumulate quickly so a central temperature database should be developed 

and maintained from the initial stages of monitoring. Also, all field and accuracy check 

forms should be organized, easily accessible, and archived in a way that allows for safe, 

long-term storage. 

• Original raw data files should be retained for all sites, and should be kept separate 

from files in which data have been manipulated. The data should be accessible, since 

someone may want to go back and calculate different metrics in the future.

• Carefully document these steps as well as any changes that you make to the data. The 

checks can be conducted using a number of different software packages (e.g., Microsoft 

Excel, Hoboware, Aquarius). 

H2 Data evaluation 

Recommended steps:

1. Save the file that you are manipulating with a different file name so that you don’t 

confuse it with the original raw data file.

2. Format the data so that it is easy to work with. 

3. Trim data (as necessary) to remove measurements taken before and after the sensor is 

correctly positioned. 

4. Plot all of the measurements and visually check the data. Look for missing data and 

abnormalities. Consider doing the following, as data permits: 

• Plot air and stream temperature data on the same graph. 

• Plot stream temperature data with stage data. 

Specific things to watch for: 

• Missing data. 

• A close correspondence between water and air temperature – this indicates 

that the stream sensor may have been out of the water. 

H-2 
• Diel fluxes with flat tops – this indicates that the sensor may have been buried in 

sediment. 

Optional 

• Graphically compare data across sites. 

• Graphically compare data across years; when data from one year are 

dramatically different, there may be errors. 

• Graphically compare with data from the nearest active weather station, if 

appropriate. The closest active weather stations can be located and the daily 

observed air temperature data for those stations can be downloaded from websites 

like the Utah State University Climate Server: 

http://climate.usurf.usu.edu/mapGUI/mapGUI.php.

Additional checks (also optional) 

• If using MS Excel, use pivot tables to check for missing data. If a 30-minute 

interval is used, there should be 48 measurements per day. If there are fewer (or 

more) measurements than expected, check the original data and your field notes 

and try and determine what might have caused this to occur. 

• Flag data points for potential errors if they 

o exceed a thermal maximum of 25°C*

o exceed a thermal minimum of −1°C*

o exceed a daily change of 10°C*

o exceed the upper 5th percentile of the overall distribution 

o fall below the lower 5th percentile of the overall distribution

*These values should be adjusted to thermal limits appropriate for each location.

H3 Application of data corrections

Erratic readings with temperature sensors can occur for a number of reasons: 

• They may become dewatered during low flow conditions. 

• High flow events may bury them in sediment. 

• High flow events may move them. 

• They may become fouled from debris, aquatic vegetation, or algae. 

• Humans may cause interference. 

Errors should be addressed on a case-by-case basis. In general, there are three possible actions: 

1) Leave the data as is. 

2) Apply the correction factor. 

3) Remove the data. 

If you are inexperienced at addressing errors with continuous temperature data, consider seeking 

guidance from someone with more experience and consult references like Wagner et al., 2006. 

Table 14 in the report provides a general summary of the different types of problems that can 

occur (e.g., missing data, failed accuracy check) and recommended actions for addressing them. 

H-3 
H4 QA/QC checklist form for temperature sensor data

Technician conducting QA/QC check:

Sensor S/N:

Water or air:

Station number: 

Waterbody name:

Data trimming Date Time Technician

Programmed launch/start 

Deployment start (in 

position) 

Out of position (e.g., data 

download, maintenance) 

 

Retrieval

Accuracy checks Pass/fail Notes

Pre-deployment 

Mid-deployment 

Post-deployment 

Describe how you addressed questionable data

_____________________________________________________________________ 

Did you save the original data (pre-'cleaned')? If so, what is the file name and where is it located?

______________________________________________________________________ 

What is the file name of the ‘cleaned data’ and where is it located?

_______________________________________________________________________ 

Did you back up both the original and ‘cleaned’ data files? If so, where are the back-up files 

located?

________________________________________________________________________ 

H-4 
Checklist Yes/No Notes

Consistent units - did you check the units to 

ensure that they were consistent throughout the 

period of deployment (should be °C)?

 

Missing data - in the Notes field, describe how 

you addressed these data and why you think they 

occurred.

 

Trimming data - did you remove observations 

that were recorded when the sensor was NOT 

correctly positioned?

 

Graph - did you plot all individual data points and 

look for abnormalities? 

Graph - did you plot air and stream temperature

on the same graph and look for abnormalities? 

Graph - did you plot stream temperature and 

water level (if available) on the same graph and look 

for abnormalities?

Graph – did you graphically compare data across 

sites? 

Graph – did you graphically compare data from the 

same site across different years?

Graph – did you graphically compare with data from 

the nearest active weather station?

Flags - did you flag values if they met the conditions 

below? (If you used different thermal limits, cross out 

the values below and write what you used)

 

 Exceed a thermal maximum of 25°C 

 Exceed a thermal minimum of −1°C 

 Exceed a daily change of 10°C 

 Exceed the upper 5th percentile of the overall 

distribution 

 Fall below the lower 5th percentile of the 

overall distribution 

H-5 
H5 References

Dunham, J., G. Chandler, B. Rieman, and D. Martin. 2005. Measuring stream temperature with digital 

data sensors: a user’s guide. Gen. Tech. Rep. RMRSGTR-150WWW. Fort Collins, CO: U.S. Department 

of Agriculture, Forest Service, Rocky Mountain Research Station. 15 p. Available online at

http://fresc.usgs.gov/products/papers/1431_Dunham.pdf. 

Maryland Department of Natural Resources. (nd). Quality assurance document for temperature 

monitoring. Draft Version 1.3. Available online at

http://www.dnr.state.md.us/streams/pdfs/QA_TemperatureMonitoring.pdf. 

Radtke, D.B., Kurklin, J.K., and Wilde, F.D., eds. 2004. Temperature (version 1.2): U.S. geological 

survey techniques of water-resources investigations. Book 9, chap. A6, section 6.1, 15 p.; accessed July 

28, 2004, Available at http://pubs.water.usgs.gov/twri9A6/ (accessed July 28, 2004).

Shull, D. and J. Lookenbill. 2013. Bureau of point and non-point source management continuous instream 

monitoring protocol. Prepared by the PA Department of Environmental Protection, Harrisburg, PA. 

Sowder, C., and E. A. Steel. 2012. A note on the collection and cleaning of water temperature data. Water 

4: 597-606. 

Wagner, R.J., Boulger, R.W., Jr., Oblinger, C.J., and Smith, B.A. 2006. Guidelines and standard 

procedures for continuous water-quality monitors—Station operation, record computation, and data 

reporting: U.S. Geological Survey Techniques and Methods 1–D3,51p. plus 8 attachments. Available at 

http://pubs.water.usgs.gov/tm1d3 (accessed August 30, 2011). 

Wilde, F.D. 2006. Temperature (ver. 2.0): U.S. geological survey techniques of water-resources 

investigations. Book 9, chap. A6., sec. 6.1, March 2006. Available at http://pubs.water.usgs.gov/twri9A6/

(accessed September 6, 2011).

H-6 
Appendix I 

_____________________________________________________________________________________________

Equipment checklists for pressure transducer protocols

I-1 
Equipment list for staff gage installation. 

Location Supplies list

All ⋅ Staff gage

⋅ Gage board 

⋅ Screws (stainless steel or brass)

⋅ Screwdriver

⋅ Assorted drill bits for wood and PVC 

⋅ Level

⋅ Stepladder (if installing more than one section of a staff gage)

⋅ Datasheets and field notebook

⋅ Survey equipment (auto level or laser level and stadia rod, paint 

marker or nails for marking benchmarks)

Fixed Object –

additional items

⋅ Concrete wedge anchor and nuts (stainless steel or galvanized)

⋅ Hammer or rotary drill 

⋅ Concrete drill bit

⋅ Hammer 

Streambed –

additional items

⋅ Galvanized or stainless steel pole with cap

⋅ Galvanized or stainless steel conduit straps

⋅ Pole driver or sledge hammer

⋅ Pry bar

I-2 
Equipment list for transducer installation. 

Location Supplies list

All 

⋅ PVC pipe for transducer (drilled with 1⁄2” or larger holes)

⋅ PVC pipe for data logger or barometric pressure logger

⋅ Galvanized or stainless steel conduit straps, hangars, and hose clamps 

⋅ Zip ties/cable ties

⋅ Screws (stainless steel or brass)

⋅ Screwdriver

⋅ Drill

⋅ Assorted drill bits for wood and PVC 

⋅ Level

⋅ Datasheets and field notebook

⋅ Survey equipment (see Section 4.3.5). 

If using a non-vented transducer, you also need:

⋅ Non-stretch cable or wire

⋅ Wire rope clamps

⋅ Long bolt and wing nut 

⋅ Extra-long PVC (should extend out of water in high flows) 

⋅ Solar shield 

⋅ PVC with caps for barometric transducer

If using a vented transducer, you also need: 

⋅ Garden staples 

⋅ PVC pipe for data logger 

⋅ PVC cap or locking well cap 

⋅ Stainless steel conduit straps

⋅ Long lag screws

⋅ Wire cable

Fixed object – 

additional items 

⋅ Hammer or rotary drill 

⋅ Concrete drill bit

⋅ Concrete wedge anchor and nuts (stainless steel or galvanized)

⋅ Hammer

Equipment list for elevation surveys.

Supplies list

• Auto level or laser level

• Tripod 

• Stadia rod

• Survey paint 

• Survey nails 

• Datasheet

I-3 
Equipment list for taking discharge measurements.

Supplies list

• Current meter/s

• Wading rods 

• Measuring tape and stakes

• Discharge measurement form

Equipment list for generating a profile of the channel cross-section.

Supplies list

• Automatic level or electronic total station and tripod or a 

clinometer

• Stadia rod 

• Measuring tape and stakes

I-4 
Appendix J _____________________________________________________________________________________________

Field forms for water level and flow measurements

J-1
J-2 
J-3 
J-4 
J-5 
Appendix K _____________________________________________________________________________________________

Post-retrieval QA/QC procedures for pressure transducer

data

K-1
This appendix is organized into five sections:

1. Record keeping and data storage 

2. Data evaluation

3. Application of data corrections 

4. QA/QC checklist form for pressure transducer data 

5. References

K1 Record keeping and data storage

• Make sure you set up a good record keeping and data storage system. Large amounts 

of data will accumulate quickly so a central temperature database should be developed 

and maintained from the initial stages of monitoring. Also, all field and accuracy check 

forms should be organized, easily accessible, and archived in a way that allows for safe, 

long-term storage. 

• Original raw data files should be retained for all sites and should be kept separate 

from files in which data have been manipulated. The data should be accessible, since 

someone may want to go back and calculate different metrics in the future.

• Carefully document these steps as well as any changes that you make to the data. The 

checks can be conducted using a number of different software packages (e.g., Microsoft 

Excel, Hoboware, Aquarius). 

K2 Data evaluation 

1. Save the file that you are manipulating with a different file name so that you don’t 

confuse it with the original raw data file.

2. Format the data so that it is easy to work with. 

3. Trim data (as necessary) to remove measurements taken before and after the pressure 

transducer is correctly positioned. 

4. Plot all stage measurements and visually check the data. Look for missing data and 

abnormalities. 

Specific things to watch for – 

• Missing data. 

• Values of 0 – this could mean that the pressure transducer was dewatered. 

Another possibility (with vented transducers) is that moisture got into the cable 

and caused readings of zero water depth.

• Values flat-lining at 0°C/32°F – the stream pressure transducer is likely encased 

in ice.

K-2 
• Negative values – if unvented transducers are being used, this may indicate that 

the barometric pressure correction is off. This could occur for a number of 

reasons: 

o The land-based transducer is not close enough to the stream pressure 

transducer to accurately capture barometric pressure. 

o If the land-based transducer is housed in PVC pipe that has a solid bottom, 

condensation and laterally blown rain and snow can penetrate through the 

drilled holes and collect in the bottom, filling the pipe to a depth sufficient 

to inundate the ports through which the barometric pressure is 

compensated. Thereafter, “barometric pressure” is actual barometric 

pressure plus a small amount of pressure due to this accumulated water.

• Outliers or rapidly fluctuating values – the stream pressure transducer may 

have moved (e.g., due to a high flow event or vandalism). 

In addition, consider doing the following, as data permits – 

• Plot stage and temperature data on the same graph. Watch for the following 

signals in the temperature data:

o Diel fluxes with flat tops – this indicates that the pressure transducer may 

have been buried in sediment. 

o A close correspondence between water and air temperature (if air 

temperature data are available) – this indicates that the pressure transducer 

may have been out of the water. 

Optional 

• Graphically compare data across years; when data from one year are 

dramatically different, there may be errors. 

• Graphically compare with precipitation data from the nearest active weather 

station, if appropriate. The closest active weather stations can be located and the 

daily observed precipitation data for those stations can be downloaded from 

websites like the Utah State University Climate Server: 

http://climate.usurf.usu.edu/mapGUI/mapGUI.php.

• Graphically compare with data from the nearest USGS stream gage, if 

appropriate. The closest active USGS gage can be located and the daily flow data 

for those gages can be downloaded from the USGS National Water 

Information System (NWIS) website:

http://waterdata.usgs.gov/usa/nwis/rt.

K3 Application of data corrections

Erratic readings with pressure transducers can occur for a number of reasons: 

• They may become dewatered during low flow conditions. 

• High flow events may bury them in sediment. 

• High flow events may move them. 

• They may become fouled from debris, aquatic vegetation, or algae. 

• Humans may cause interference. 

• They may become encased in ice. 

K-3 
• If moisture gets into the cable of a vented transducer, it may result in erratic readings or 

readings of zero water depth. 

• If the cable of a vented transducer gets kinked or plugged, it can result in the data not 

being corrected for barometric pressure. 

Errors should be addressed on a case-by-case basis. In general, there are three possible actions: 

1) Leave the data as is. 

2) Apply the correction factor. 

3) Remove the data. 

If you are inexperienced at addressing errors with continuous temperature data, consider seeking 

guidance from someone with more experience and consult references like Wagner et al., 2006. 

Table 20 in the report provides a general summary of different types of problems that can occur 

(e.g., missing data, failed accuracy check) and recommended actions for addressing them. 

K-4 
K4 QA/QC checklist form for pressure transducer data

Technician conducting QA/QC check: Transducer S/N: 

Station number: Waterbody name:

Data trimming Date Time Technician

Programmed launch/start 

Deployment start (in 

position) 

Out of position (e.g., data 

download, maintenance) 

 

Retrieval

Accuracy 

checks

Date Time Staff gage 

reading

Pressure transducer 

reading

 

Describe how you addressed questionable data. 

_____________________________________________________________________ 

Did you save the original data (pre-'cleaned')? If so, what is the file name and where is it located?

______________________________________________________________________ 

What is the file name of the ‘cleaned data’ and where is it located?

_______________________________________________________________________ 

Did you back up both the original and ‘cleaned’ data files? If so, where are the back-up files 

located?

________________________________________________________________________ 

K-5 
Checklist Yes/No Notes

Consistent units - did you check the units to 

ensure that they were consistent throughout the 

period of deployment?

 

Missing data - in the Notes field, describe how 

you addressed these data and why you think they 

occurred.

 

Values of 0 or negative values - in the Notes 

field, describe how you addressed these data and 

why you think they occurred.

Trimming data - did you remove observations 

that were recorded when the pressure transducer 

was NOT correctly positioned?

 

Graph - did you plot all individual data points and 

look for abnormalities? 

Graph - did you plot temperature data on the same 

graph and look for abnormalities? 

Graph – did you graphically compare data from the 

same site across different years?

Graph – did you graphically compare with discharge

data from the nearest USGS stream gage?

Graph – did you graphically compare with

precipitation data from the nearest active weather 

station?

K5 References

Shedd, J.R., and C. Springer. 2012. Standard operating procedures for correction of continuous stage 

records subject to instrument drift, analysis of instrument drift, and calculation of potential error in 

continuous stage records. Washington State Department of Ecology, Environmental Assessment Program 

– EAP No. EAP082. Available at 

http://www.ecy.wa.gov/programs/eap/qa/docs/ECY_EAP_SOP_CorrectionOfContinuousStageRecords_v

1_0EAP082.pdf. 

Shull, D. and J. Lookenbill. 2013. Bureau of point and non-point source management continuous instream 

monitoring protocol. Prepared by the PA Department of Environmental Protection, Harrisburg, PA. 

Wagner, R.J., Boulger, R.W., Jr., Oblinger, C.J., and Smith, B.A., 2006. Guidelines and standard 

procedures for continuous water-quality monitors—Station operation, record computation, and data 

reporting: U.S. Geological Survey Techniques and Methods 1–D3, 51p. and 8 attachments. Available at 

http://pubs.water.usgs.gov/tm1d3 (accessed August 30, 2011). 

K-6 
National Center for Environmental Assessment 

Office of Research and Development

Washington, DC 20460