ONEOK works to minimize the impact of our operations on the environment while maintaining safe and reliable service and following applicable environmental laws and regulations.

Our efforts are largely focused on reducing emissions, land and water conservation and remediation. Using an integrated, systems-based approach to manage the environmental aspects of our operations helps us to identify, assess and control risks.


ONEOK may be subject to physical and financial risk associated with climate change. Our company’s environmental actions focus on minimizing the impact of operations on the environment while providing safe and reliable essential energy solutions for our customers.

For more information on potential risks associated with climate change, see ONEOK’s 2019 Annual Report at

ONEOK looks for opportunities to reduce emissions through strategic programs and initiatives, and company leadership has identified greenhouse gas (GHG) emissions as a material area of focus.

In 2020, ONEOK joined Our Nation’s Energy Future Coalition (ONE Future), a natural gas industry-led organization dedicated to voluntarily achieving meaningful reductions in methane emissions across the natural gas value chain. The coalition, made up of more than 25 natural gas companies, surpassed its original goal to lower methane emissions intensity to 1% by 2025 for the entire natural gas value chain, but continues to work toward further reducing emissions and promoting a sustainable energy future. Through the coalition, ONEOK has committed to achieve a methane emissions intensity target for our natural gas transmission and storage operations by 2025.

For more information on ONE Future, visit

In addition to developing and maintaining an emissions inventory in accordance with the U.S. Environmental Protection Agency (EPA), ONEOK works to reduce emissions by:

  • Improving the efficiency of various pipelines, natural gas processing facilities and NGL fractionation facilities.
  • Evaluating opportunities and implementing, where practical, emissions control and carbon capture technologies.
  • Implementing best practices around equipment and engineering controls to reduce the loss of methane from facilities.
  • Using electric power at many compressor stations across ONEOK’s operations, which reduces potential GHG emissions that may result from combustion in natural gas-powered compressor engines.
  • Partnering with electric generation facilities transitioning from coal to natural gas-powered operations, which provides reliable service while reducing emissions.

ONEOK uses technology to support these efforts, including:

  • Periodic use of optical gas imaging (OGI) cameras that rapidly scan large areas and visually pinpoint leaks in real time, enabling the fast detection of carbon emissions.
  • Ultrasonic technology that uses sound frequency to identify any escaping gases.
  • Photoionization detectors (PIDs) and flame ionization detectors (FIDs), generally used with OGI cameras, to help detect a variety of gases, including volatile organic compounds at operating facilities.


When producers drill for crude oil and natural gas, flaring, or the controlled burning of natural gas at the wellhead, may occur if there isn’t sufficient capacity to gather and process the natural gas and NGLs that are produced along with the crude oil. As the largest operator of midstream infrastructure in the Williston Basin, ONEOK is committed to helping producers reduce the amount of natural gas being flared by investing in infrastructure to capture, process and transport these essential products to markets.

Our long-standing commitment to the region has resulted in adding nearly 1.4 billion cubic feet per day (Bcf/d) of natural gas processing capacity over the last 10 years, with 400 million cubic feet per day (MMcf/d) added in 2019 and 2020 alone. Total natural gas flaring in the region has decreased from an all-time high of 36% in September 2011 to 11% in May 2020, with additional reductions expected by year-end 2020.


The natural gas gathering and processing segment recently completed a project to replace natural gas compressors, which pressurize natural gas and enable it to efficiently flow through pipelines, with electric equipment at ONEOK’s Lindsay, Oklahoma, compressor site. The new electric engines, which produce no combustion emissions, are expected to reduce emissions by approximately 40,000 metric tons of CO2e annually. The project reduced sitewide GHG emissions at Lindsay by more than 94% and enabled additional compressor shutdowns on ONEOK’s system.


ONEOK is a member of the Interstate Natural Gas Association (INGAA) and participates in INGAA’s commitment to continuously improving practices to minimize methane emissions from interstate natural gas transmission and storage operations in a prudent and environmentally responsible manner.

INGAA member companies commit to the following:

  1. Minimizing methane emissions from natural gas pipelines and pneumatic controllers. This commitment includes evaluating and implementing voluntary practices, such as those found in the EPA’s Natural Gas STAR Program, which ONEOK has participated in since 2000.
  2. Minimizing methane emissions from natural gas storage wells and compressor stations.
  3. Developing effective practices and sharing information.

For more details on INGAA’s methane emissions commitment, see the association’s website at


ONEOK uses several different metrics to track our impact on the environment.

Visit for details.

We strive to be a zero-incident workplace, and our company’s commitment to evaluating opportunities for increasing efficiencies and emissions control is evident in continuing improvements to our Agency Reportable Environmental Event Rate (AREER).

AREER is an internal environmental metric that promotes continued reduction of releases and emission events reportable to a state or federal agency, and is an element of the short-term incentive program for all ONEOK employees.

ONEOK has achieved AREER improvements each year since the rate was established. The 2019 AREER of 0.79 beat that year’s target of 0.95 and showed a 25% improvement over the 2018 results of 1.05. ONEOK’s 2020 AREER target is 0.71.

AREER is defined as the total number of releases and excess emission events that trigger a federal, state or local environmental reporting requirement (with some exceptions to account for events outside ONEOK’s control, planned maintenance and disparities in reporting requirements across the company’s operations) per 200,000 work hours.


As a midstream service provider, ONEOK gathers, transports, fractionates, processes and stores hydrocarbon products and delivers those products into the marketplace. Based on 2019 EPA greenhouse gas reporting threshold levels, ONEOK reported emissions of approximately 64.2 million metric tons (MMT) of carbon dioxide equivalents (CO2e).2

Greenhouse Gas Emissions Million Metric Tons (MMT) CO2e20152016201720182019
Scope 1

Carbon Dioxide

Methane (CO2e)

Nitrous Oxide (CO2e)

Scope 2
Scope 345.947.549.658.157.4

The increase in year-over-year greenhouse gas emissions is primarily due to system expansions through new capital projects, debottlenecking and increased utilization.
Scope 1 emissions as reported to the EPA under the Mandatory Greenhouse Gas Reporting Rule. Total Scope 1 emissions, including estimates from facilities outside of the reporting rule, can be found in ONEOK’s ESG Performance Data Table.

SCOPE 1 EMISSIONS: Emissions that directly result from ONEOK’s operations, such as natural gas combustion from compressor engines and process heaters; methane and carbon dioxide that escape from operating equipment; venting sources (valves, connectors, open-ended lines, flanges, relief valves and meters); and other processes common to natural gas systems.

SCOPE 2 EMISSIONS: Indirect GHG emissions that occur from energy consumption, where the energy is generated by another entity, such as emissions from the generation of purchased electricity, steam, heat or cooling. These emissions physically occur at the utility where the energy is being generated and would be considered Scope 1 direct emissions for the utility.

SCOPE 3 EMISSIONS: Emissions as reported to the EPA under the Mandatory Greenhouse Gas Reporting Rule that would result assuming complete combustion or oxidation of NGL products that ONEOK delivers to customers, calculated using the annual volume of each fractionated product and multiplying it by an emission factor. Products covered under the rule include ethane, propane, butane, isobutane and natural gasoline. If the products are combusted or oxidized by downstream customers, that portion would be considered Scope 1 direct emissions for the customer. Scope 3 does not include the sale of natural gas to end users.

1 ONEOK’s operations do not result in the emitting of ozone-depleting substances, such as those used in aerosols and refrigerants, into the atmosphere. 2 Carbon dioxide equivalent (CO2e) is a metric used to compare the emissions from various greenhouse gases and is determined by multiplying the tons of a specific greenhouse gas by its associated global-warming potential.


As part of our commitment to environmental sustainability and transparency, ONEOK tracks and discloses emissions data for nitrous oxides (NOx), sulfur oxides (SOx), hazardous air pollutants (HAPs) particulate matter-10 (PM10) and volatile organic compounds (VOCs) for all facilities required to report air emission inventories.

Thousand Tons20152016201720182019


ONEOK uses a variety of sustainable practices to minimize and offset effects our operations and capital-growth projects may have on ecosystems and terrestrial biodiversity.

Our approach to land and water management includes evaluating sites that reduce impacts; activities focused on restoring habitats affected during construction; and assessing water use and opportunities for reduction. Additional focus areas related to conservation include improving natural habitats and public use areas, employing extensive leak detection processes to monitor assets, and implementing programs to manage waste reduction, recycling and energy use.


Facility and pipeline construction planning often requires ONEOK to adopt a scalable approach to site selection and pipeline routing. We are committed to evaluating project sites and pipeline routes designed to minimize the impacts on communities and the environment, while also allowing for economic viability of the project, and safe construction and operation once complete. The environmental evaluation of a proposed project involves identification of high conservation value (HCV) factors within a proposed route that include the following:

• Threatened and endangered (T&E) species presence (federal and state listed).
• Proximity to T&E species critical habitats.
• Protected lands (state, federal and tribal).
• Documented resources of historical or cultural significance.
• Land use (e.g., forests, farmland and rangeland).
• Proximity to populated areas.

Wherever possible, ONEOK refrains from site selection in protected areas and areas of high conservation value. We seek to avoid and minimize impacts to sensitive resources by considering alternate locations or adjusting construction methods and site design.

Preliminary route and site locations undergo extensive environmental reviews and permitting where applicable before construction begins. Our minimization approach is specific to each project and location and may include construction timing restrictions, project alteration, buffered exclusion zones and alternative construction methods. Where possible, we also co-locate projects with existing pipeline routes to limit habitat fragmentation.


Water use, supply and resource conservation are important components of ONEOK’s operations. By assessing water use through benchmarking and monitoring equipment, we identify opportunities for water reduction and reuse; potential inefficiencies across operations, including undetected repairs like buried leaks; and cost savings.

Wherever possible, we strive to minimize water use by reclaiming it in operations processes and construction projects. During hydrostatic testing of new pipeline assets, our project teams reuse water for testing multiple pipe segments or recycle it where appropriate. Water is a valuable resource in the fractionation of NGLs. Our facilities have adopted processes to maximize water efficiency and reduce wastewater generation by recovering water for reuse.

During construction, ONEOK takes proactive steps to assess and lessen potential effects to water resources. This includes a three-tiered conservation approach:

Avoidance: In the early stages of a project, water resource data is reviewed to identify water crossings that may need to be avoided.

Minimization: We hold employees and contractors to high standards and require them to follow what we believe to be best management practices during construction. When avoidance is not possible, we attempt to reduce impacts by narrowing the right of way and identifying the best crossing method to minimize disturbances to stream beds or surface water. We also use various environmental controls like sediment barriers, storm water filtration devices and refueling offsets, and follow regulations for stream bank stabilization and restoration.

Mitigation: Where avoidance and minimization cannot be accommodated, we work with local, state and federal regulators to mitigate impacts appropriately.

This three-tiered conservation approach was critical during the planning and construction of approximately 1,200 miles of pipeline during 2019 as part of our capital-growth projects in the Rocky Mountains, Mid-Continent and Texas Gulf Coast regions.

ONEOK avoided 60% of the waterbodies and wetlands along planned pipeline routes. This included fully rerouting construction to avoid 922 waterbodies or wetlands, and using trenchless boring technology to install pipe under 342 waterbodies and wetlands without disturbing the environment above. This technique is a common form of avoidance, which greatly reduces potential temporary crossing impacts.

When unable to be avoided, ONEOK uses best management practices designed to minimize any potential temporary impacts of crossing waterbodies and wetlands, including installing barriers to protect sediment from entering the waterbodies and constructing temporary bridges that allow workers and equipment to cross waterbodies with limited impact.


Pipeline system integrity is key to our operational success. ONEOK dedicates considerable resources to the evaluation, development and implementation of leak detection systems.

Leak detection methods are broadly classified into two categories:

  • External leak detection methods: aerial patrol and on-site inspection.
  • Internal leak detection methods: pressure flow monitoring and computational pipeline monitoring.

Some segments along transmission pipelines have been designated as high consequence areas (HCAs) in accordance with the Pipeline and Hazardous Materials Safety Administration (PHMSA) guidance and federal regulations. HCAs for hazardous liquid pipelines are defined as populated areas, drinking water sources and unusually sensitive ecological resources. ONEOK has implemented additional hazard assessment and prevention programs for HCAs that help manage asset integrity risks.


We work closely with regulators to develop appropriate mitigation and conservation approaches that serve to offset potential environmental impacts from our projects.

The restoration of habitats that may be affected during the construction of large infrastructure projects remains a key focus, and during 2019 we restored 13,700 acres of habitat. This includes determining the appropriate seed mixes and plant species in the area as well as properly separating topsoil to restore the right of way following construction. ONEOK takes into account landowner concerns during restoration and communicates restoration expectations to contractors.

Arbuckle II Pipeline construction (top) and completed restoration (bottom) in southern Oklahoma


Coating application on the Arbuckle II Pipeline in OklahomaCoating application on the Arbuckle II Pipeline in Oklahoma

Coating application on the Arbuckle II Pipeline in Oklahoma


ONEOK has significantly reduced waste and improved reliability on pipeline construction projects by using an automated multicomponent spray technology to apply epoxy coating to pipe joints. The coating application is necessary to protect welded pipeline connections from corrosion but is traditionally applied by hand, which requires the use of liter pails and single-use application equipment. The spray application technology is faster, more reliable and produces less waste.

Over the past two years, implementing the technology has eliminated:

  • The use of 60,000 plastic pails.
  • Approximately 20% of epoxy coating waste.
  • Related waste associated with hand application, including brushes, rollers, mixers and gloves.


ONEOK is nearing completion on a multiyear initiative to build a remote monitoring network on our current cathodic protection system, which reduces pipeline corrosion. Installing solar-powered remote monitoring units on pipelines to monitor cathodic protection systems, rather than relying on physical monitoring, has reduced vehicle mileage by approximately 200,000 miles per year and reduced CO2 emissions by 122 tons annually. Remote monitoring also has increased system knowledge by allowing daily monitoring of locations and improved data accuracy.


Continually improving waste reduction and recycling programs helps divert waste from landfills and isimportant to our sustainability efforts.

ONEOK uses a resource management software system to streamline reporting and provide anunderstanding of recycled materials and waste quantities. By analyzing data in the system, we can more easily identify opportunities for reducing waste, recycling materials when possible and improving processes for more sustainable approaches to waste management.

Tracking data in this single software solution has allowed for transparency and visibility in waste volumes and recycling.

For data, visit


ONEOK purchases and works to use electricity efficiently to operate facilities, equipment and offices across our businesses. Electricity purchases from various third-party utility providers across our operations include electricity from renewable resources, such as wind and solar, in addition to natural gas-fueled and other types of generation resources. ONEOK tracks the fuel supply from third-party electricity purchases to determine our energy usage from renewable resources.


Renewable fuel sources include wind, solar, hydroelectric, biomass and other renewable resources. Nonrenewable sources include coal, natural gas, nuclear, oil and all unknown or unspecified wholesale market supplied electricity.
Until the specific generation resources are known, and where the organized wholesale market is known by ONEOK’s utility providers, ONEOK electric consumption data uses generation data reported by the wholesale marketplace as a proxy. The disposition by our utility providers of any Renewable Energy Credits associated with these generation resources is undetermined.


Formed in 2019, ONEOK’s Energy Strategy Task Force is made up of representatives from across the company’s sustainability, environmental, engineering and commercial optimization groups. The task force is charged with enhancing the company’s sustainability performance related to energy consumption and usage by sharing information and expertise across company business segments and helping to identify opportunities for strategic energy projects.

Current focus areas for the group include:

  • Fuel source and electricity consumption reporting.
  • Renewable energy and other electric generation opportunities.
  • Electrification and efficiency improvements.