Q. What is the Southwest Power Pool and what does it do?
A. The Southwest Power Pool (SPP) is a nonprofit organization that operates the wholesale electricity transmission system—often called “the grid”—across all or part of seventeen states in the Midwest and West. These states include Arizona, Arkansas, Colorado, Iowa, Kansas, Louisiana, Minnesota, Missouri, Montana, Nebraska, New Mexico, North Dakota, Oklahoma, South Dakota, Texas, Utah, and Wyoming. SPP is the regional transmission organization (RTO) for its region, and it also fulfills the operational roles of an independent system operator (ISO). Today, these terms are often used interchangeably because both serve grid operations and wholesale market operations.
It is headquartered in Little Rock, Arkansas.
Figure 1. Southwest Power Pool (SPP) area.
As an RTO, SPP coordinates how electricity flows across high‑voltage power lines that carry electricity long distances. SPP develops rules to keep the grid operating safely and reliably. Without this coordination, parts of the grid could experience elevated “congestion,” meaning too much electricity is trying to flow through a limited area. This can happen during extreme weather, when demand is very high, or when transmission lines are out for maintenance.
SPP manages this flow of power from a control room that constantly monitors grid conditions, similar to how an airport’s air traffic control center guides airplanes. System operators watch for problems, adjust power flows, and work to prevent outages or emergencies as conditions change.
SPP is one of seven RTOs/ISOs overseen by the Federal Energy Regulatory Commission (FERC) (note that another of these seven is ERCOT in Texas, over which FERC has limited authority). These organizations exist to ensure fair, open access to the grid. This open access supports reliability and allows electricity buyers and sellers to participate in competitive wholesale electricity markets. The goal of the markets is to set fair prices that reflect real supply and demand.
In addition to operating the grid, SPP runs such wholesale electricity markets in its region. The markets rely on detailed rules that SPP develops with input from many stakeholders, including utilities, consumer groups, power suppliers, and others. State utility regulators in SPP’s territory, through the SPP Regional State Committee, also play a key role. Any changes to SPP’s rules ultimately require approval from FERC, which regulates SPP’s activities.
Q. What does it mean when you refer to the “wholesale electricity transmission system” or the “grid?”
A. In SPP’s region, the “grid” refers to the high‑voltage transmission system that moves wholesale electricity across long distances and across state lines. These large-scale transmission lines fall under the jurisdiction of the Federal Energy Regulatory Commission (FERC), and SPP is responsible for operating them. By contrast, the lower‑voltage power lines that deliver electricity directly to homes and businesses—often the ones you see on local streets—are called distribution lines. Distribution systems are usually regulated by state or local authorities or operated by federal power marketing administrations but are not overseen by FERC.
A key difference between transmission and distribution lines is thus the voltage. Transmission lines carry electricity at very high voltages so it can travel long distances efficiently. Distribution lines carry electricity at lower voltages so it can be safely delivered to customers.
SPP operates the high‑voltage transmission system and FERC oversees the rates, terms, and conditions for the transmission of electricity that flows across these lines. This entire network of high‑voltage lines is what SPP refers to as the wholesale electricity transmission system, or simply “the grid.”
The following diagram illustrates how electricity travels, including SPP’s operation of transmission lines subject to FERC’s jurisdiction:
Figure 2. Electricity supply and demand process.
You have probably seen tall poles carrying electricity along a strip of land that look like the tall metallic pole above (second from the left); this is an example of high voltage electricity transmission managed by SPP in its territory.
Q. Does SPP own the electric transmission infrastructure that it operates?
A. No. SPP operates the transmission system but does not own the transmission lines, poles, or equipment. When a utility chooses to join SPP, it keeps ownership of its transmission facilities but gives SPP control over how those facilities are operated. Because SPP operates these lines independently of the utilities that own them, it is called an independent system operator (ISO). SPP also functions as the regional transmission organization (RTO) for its territory, as designated by the Federal Energy Regulatory Commission (FERC).
Utilities that join SPP and transfer operational control of their transmission assets are known as transmission owners. They receive compensation—through rates developed in SPP’s stakeholder processes and ultimately approved by FERC—for the use of their transmission lines. These payments follow SPP’s rules for cost allocation.
Q. What does “wholesale electricity” mean, and why does SPP operate a market for it?
A. To understand wholesale sales of electricity, consider the graphic below. In the graphic, the electric generation plant (Generator) sells electricity to a utility or other company (Reseller) who in turn intends to resell that electricity to homes and businesses (Retail Customer). The sale from Generator to Reseller is a wholesale sale of electricity and FERC almost always has jurisdiction over the rates charged for that sale. Wholesale sales in SPP’s territory are in interstate commerce because the electricity moves across a multi-state, interconnected grid.
In contrast, when your local utility sells electricity directly to you—for your home or business—that is considered a retail sale and is not regulated by FERC. Instead, retail rates are usually regulated by state public utility commissions, city governments (for municipal utilities), or cooperative boards (for electric co‑ops). If you have concerns about your electric bill or retail service, the right place to go is your utility or your state or local regulator, not SPP or FERC.
Figure 3. Wholesale and retail process and relationships.
Q. Why are SPP processes and markets important?
A. Even though SPP does not manage your personal electric bill or the service to your home or business, its actions can have a major impact on the price and reliability of electricity in your region. SPP also plays an important role in carrying out state and federal energy and environmental policies.
One of SPP’s most important responsibilities is to keep the grid in constant balance. Electricity supply must always equal electricity demand. To do this, SPP runs a real‑time energy market, which buys electricity for immediate delivery. Prices in this market update every five minutes based on actual grid conditions—such as sudden generator outages, unexpected weather, or changes in electricity demand.
SPP also operates a day‑ahead energy market, where electricity for the next day is bought and sold based on forecasts of demand and the supply offered by generators. Most electricity in SPP’s region is traded in this day‑ahead market. It helps generation companies plan ahead, schedule workers, and arrange fuels. It also lets SPP anticipate and manage excess transmission congestion, which can occur when too much electricity tries to move through part of the grid. By planning one day in advance, SPP can choose the lowest‑cost combination of resources while preventing overloads on transmission lines.
In addition to energy markets, SPP also runs markets to procure ancillary services. These are specialized products that help maintain reliability and power quality. They include reserves that can quickly respond to unexpected events—like a power plant suddenly going offline—and regulation services that support grid frequency and balance.
Together, these processes and markets allow SPP to maintain a reliable grid, support competitive prices, and carry out key regional and national energy objectives.
Day-Ahead Energy Market
The day‑ahead energy market is where SPP schedules electricity production one day before it is needed. In this market, SPP uses forecasts—especially weather forecasts—to estimate how much electricity customers will use the next day. Generators then submit bids offering how much power they can produce and at what cost.
SPP runs a computerized model that matches these supply offers with the expected demand for each hour of the next day. The system selects the lowest‑cost combination of resources that can meet the region’s energy needs. Because power plants often need several hours to start up, this advance scheduling allows generators to plan ahead, arrange fuel, schedule staff, and prepare equipment.
Most electricity in SPP’s region is bought and sold in the day‑ahead market rather than in the real‑time market. Day‑ahead scheduling also helps SPP identify and manage transmission congestion, which occurs when a section of the grid becomes overloaded. Excessive congestion can raise safety risks—like transmission lines overheating and sagging toward nearby structures or vegetation—so SPP uses day‑ahead modeling to prevent these overloads. Sometimes this means scheduling a generator that is not the absolute lowest‑cost option, but is better located to avoid congestion during high‑demand periods.
Through this process, SPP ensures that electricity supply for the next day is reliable, cost‑effective, and aligned with the physical limits of the grid.
Real-Time Energy Market
The real‑time energy market is where SPP balances the grid as conditions change throughout the day. Even though most electricity is scheduled in the day‑ahead market, actual conditions can differ from forecasts. For example, a generator might unexpectedly go offline, temperatures may be hotter or colder than predicted, or demand may rise quickly in one part of the region.
When these changes occur, SPP uses the real‑time market to adjust supply so that electricity production and electricity use stay in balance—something the grid requires at every moment. In this market, SPP buys electricity for immediate delivery from resources that are already connected to the grid and can quickly increase their output. Demand response resources—customers who can reduce usage—may also be used to help balance the system.- Ancillary Services Markets
SPP also operates several ancillary services markets, which supply specialized products needed to keep the grid reliable and stable. These services help SPP maintain the constant balance between electricity supply and demand and ensure high‑quality power across its territory.
The grid must always be prepared for unexpected problems—such as a generator suddenly failing or a rapid change in electricity use. To handle situations like these, SPP buys different types of operating reserves:
- Regulation Up/Down – Resources that quickly adjust output to help keep the grid’s frequency stable. These resources constantly fine‑tune the balance between supply and demand.
- Spinning Reserves – Power plants that are already running (“spinning”) but can rapidly increase output if needed. Because they are already online, they can respond quickly to emergencies.
- Supplemental Reserves – Resources that are not currently operating but can start generating power within about ten minutes when called upon.
- Ramp Capability Up/Down – Resources that can increase or decrease output at a specific rate to help manage sudden changes in system conditions.
- Uncertainty Reserves – Products that help the system adjust to unpredictable variations, such as possible changes in intermittent energy resources or sudden changes in demand.
These ancillary services are essential for maintaining system stability, responding to emergencies, and preserving the quality of electricity across the SPP region.
Note: SPP previously operated the Western Energy Imbalance Service (WEIS) to give certain western utilities access to market benefits even if they were not full SPP members. Some of these utilities have now joined SPP as full RTO members, while others are exploring different options.
With this expansion, SPP has become the first RTO to operate in both the Eastern and Western interconnections of the U.S. power grid—an important milestone. Because so many western utilities have transitioned into full SPP membership, the WEIS program was discontinued on April 1, 2026.
As a result, SPP now operates both an East and West Balancing Authority Area, reflecting its larger geographic footprint and expanded responsibilities.
For additional background and guidance on western markets, please see OPP’s Western Markets Explainer.[1]
Q. Who participates in SPP’s matters?
A. Active participants in SPP are usually companies or organizations that pay an annual fee to become SPP members. Membership gives them voting rights and the ability to take part in SPP’s stakeholder processes, committees, and working groups. As of April 2026, SPP has 147 members, including power producers, investor‑owned and municipal utilities, electric cooperatives, independent transmission companies, power marketers, state agencies, large customers, and public interest organizations.
A subset of these members serves on an important group called the Members Committee, which reports directly to the SPP Board of Directors. This committee plays a major advisory role and helps convey the views of SPP’s membership to the Board.
Q. How is SPP governed?
A. SPP is led by an executive team and overseen by an independent Board of Directors made up of ten members. Nine directors are elected, and the President and CEO of SPP serves as the tenth director automatically. Directors serve three‑year terms, and there are no term limits. Most Board meetings are open to the public, and SPP posts all meeting materials, agendas, and minutes on its website.
When a Board vacancy occurs, the Corporate Governance Committee nominates candidates who must have senior‑level experience in areas like finance, accounting, transmission or generation planning or operations, law and regulation, commercial markets, or risk management. SPP members vote on nominees at an official meeting. The Board then selects its own chair and vice chair for two‑year terms, though the President and CEO of SPP is not eligible for those roles.
The Board oversees several committees, including the Corporate Governance Committee, Finance Committee, Human Resources Committee, Oversight Committee, and Strategic Planning Committee. However, the Members Committee is one of the most significant. This committee can include up to 24 SPP members representing various sectors—such as utilities, power producers, and consumer interests. Although it does not vote on behalf of the Board, it provides key advice and takes “straw votes” that help the Board understand whether the broader membership supports a proposed action.
Q. What is the SPP Regional State Committee?
A. The SPP Regional State Committee (RSC) gives state utility regulators in SPP’s territory a formal way to participate in decisions affecting the regional electric grid. Each state participating in SPP appoints a state utility commissioner to the RSC, and each state gets one vote, regardless of size or population.
The RSC plays a uniquely strong role compared with similar committees in other RTOs/ISOs. In several key areas, decision‑making authority is effectively shared between the RSC and the SPP Board of Directors.
Under the RSC’s bylaws, the committee has primary responsibility for several important regional issues:
- Resource adequacy – making sure the region has enough electric generation to meet demand.
- Whether remote resources are included in the regional transmission plan – determining if resources far from load centers, such as proposed solar arrays, wind farms, or other power resources, should be planned into the system.
- Cost allocation for transmission upgrades – deciding how the costs of new transmission projects should be divided among utilities and customers.
- Allocation of financial transmission rights – overseeing how certain market‑related transmission rights are assigned.
Through these responsibilities, the RSC ensures that states retain authority over major policy issues that affect reliability, costs, and long‑term planning in the SPP region. In practical terms, this means that states—acting through the RSC—continue to shape some of the most influential aspects of how the regional grid operates.
Q. What stakeholder processes does SPP have?
A. SPP, like other RTOs/ISOs, uses a tiered committee structure that allows stakeholders to give input on major issues and advise the SPP Board.
Figure 4. SPP committee structure.
Stakeholders include SPP members, market participants, transmission customers, government staff with jurisdiction over SPP or its members, and SPP staff.
The highest‑level stakeholder body is the Markets and Operations Policy Committee (MOPC) — pronounced “MOP‑see.” Every SPP member appoints one representative to the MOPC. For voting purposes, the committee is divided into two sectors:
- Transmission‑Owning, and
- Transmission‑Using.
Each sector votes, and then SPP calculates a weighted average of the two sector votes. A proposal must receive 66% support in this combined weighted vote to pass.
Below the MOPC are numerous Organizational Groups, which include technical committees, working groups, and advisory groups. These groups examine issues in detail before they reach the MOPC. Examples include the Economic Studies Working Group, the Market Working Group, and the Transmission Working Group.
Members of these groups are appointed by the SPP Board, which aims for balanced representation across different member types and geographic regions. Organizational Groups may also create task forces to study more specific topics. Voting in these groups is typically by a simple majority.
Through this working‑group structure, stakeholders at many levels can participate in shaping market rules, transmission planning processes, and operational policies before they reach the MOPC and ultimately the Board.
Q. How are decisions made in SPP?
A. SPP’s decision‑making process involves both its Board of Directors and its members, with each playing an important role.
The Board has primary responsibility for major decisions, similar to boards at other RTOs/ISOs. But in SPP, the member organizations also have significant influence. The Members Committee, made up of representatives from different sectors, takes straw votes on proposals that are headed to the Board. These votes are not binding, but they help the Board understand whether there is broad support among SPP’s membership before acting.
A central issue in SPP governance, and across all RTOs/ISOs, is who has the right to file proposed changes to tariffs or market rules with the Federal Energy Regulatory Commission (FERC). These rights are authorized under Section 205 of the Federal Power Act. Entities that hold Section 205 filing rights can submit proposals directly to FERC rather than filing a complaint.
In SPP:
- SPP and its transmission owners share Section 205 filing rights.
- Transmission owners hold exclusive filing rights over transmission service for facilities they control.
- SPP holds filing rights over most other tariff provisions.
- For matters involving transmission planning, cost allocation, or resource adequacy, the Regional State Committee (RSC) makes the decisions, and SPP files the proposal with FERC on behalf of the RSC.
Although SPP has the authority to file competing proposals when filing on behalf of the RSC, there is no record of SPP ever doing so. This reflects how closely SPP, its members, and the states coordinate on major policy issues.
Q. How can people keep track of what is going on at SPP?
A. SPP makes it easy to follow its activities through the Events page on its website (SPP.org). The front page includes a link that takes you directly to a monthly calendar showing dozens of meetings and events scheduled throughout the month.
Here is a sample of a monthly events calendar on the SPP website:
Figure 5. Example of SPP monthly events calendar.
When you click on a meeting in the calendar, you will see:
- A contact person for questions
- A registration link
- A documents folder
The documents folder includes materials for the upcoming meeting as well as links to prior meetings. This allows you to review agendas, presentations, minutes, and recent discussions so you can understand the background of an issue.
For example, if you select the April 8, 2:00 p.m. “Markets+ Settlements User Forum Net” meeting, you will find the contact information, the registration button, and access to both current and past meeting documents — all in one place. This streamlined setup helps the public, stakeholders, and anyone interested in SPP matters stay informed and engaged.
Figure 6. Example of information on individual meetings listed in SPP monthly events calendar.
Q. How can a person or group interested in SPP issues influence regional decisions?
A. SPP provides several ways for people and organizations to engage, but the level of influence depends on whether the participant is an SPP member or otherwise recognized stakeholder.
SPP meetings are open to the public, and anyone can attend to listen and learn. However, only members and certain other qualified entities—such as government agencies with jurisdiction over SPP or its members—can formally submit requests for SPP to consider changes to its market rules or tariff. This formal process is known as the Revision Request (RR) Process.
Because SPP’s issues are often technical, detailed, and shaped by more than two decades of stakeholder discussion, newcomers may find it helpful to partner with existing members or stakeholders who share similar concerns or policy goals. These groups already understand SPP’s processes and may welcome collaboration, whether the issue involves rates, environmental policy, reliability, or other topics.
Individuals or organizations can also work with their state public utility commission to understand their state’s positions on regional issues—especially those in areas where the Regional State Committee (RSC) has primary responsibility.
The National Association of Regulatory Utility Commissioners (NARUC) maintains a list of state commissions, which can help interested parties identify the appropriate agency in their state.
Q. How do I learn more about SPP and regional electric affairs?
A. A great place to start is the SPP website at SPP.org. The Stakeholder Center includes a link to Stakeholder Training, where you can access the SPP Learning Center (registration required). The Learning Center offers a wide range of materials, including introductory and advanced training, online classes, self‑study modules, and other educational resources.
The Federal Energy Regulatory Commission (FERC) also provides helpful background on the electric industry, including information about SPP, through its 2024 Energy Primer, a detailed guide to how energy markets work.
If you want more help or have questions about navigating FERC’s website and resources, you can contact the Office of Public Participation (OPP). OPP can provide information about SPP, guidance on engaging in regulatory processes, and help connecting to additional resources. You can reach OPP by email at [email protected] or by phone at (202) 502‑6595. OPP also has its own page on the FERC website at https://www.ferc.gov/OPP.
[1] Western Energy Markets Explainer | Federal Energy Regulatory Commission (ferc.gov)