The Federal Energy Regulatory Commission made headlines this week with one of the most consequential grid policy actions in a generation. On June 18, 2026, FERC issued tailored show cause orders to all six RTO/ISO regions under its jurisdiction, directing them to justify or reform how large loads, including AI data centers and advanced manufacturing facilities, connect to the transmission grid. The move fulfills the DOE’s October 2025 directive to FERC and sets the stage for a dramatic reshaping of large load interconnection policy across two-thirds of the country’s electric load. And it takes its clearest cues from a framework that Southwest Power Pool pioneered: the High Impact Large Load (HILL) process.
Why Show Cause Orders Instead of a NOPR?
When DOE Secretary Chris Wright invoked the rarely-used Section 403 authority in October 2025 to direct FERC to act on large load interconnection, most energy lawyers and grid policy watchers expected the conventional response: a Notice of Proposed Rulemaking (NOPR). A NOPR would have kicked off a formal comment period, followed by deliberation, followed eventually by a final rule. That process routinely takes two to four years. Given that data center developers are signing interconnection agreements today and AI infrastructure investment decisions are being made on quarterly cycles, the traditional rulemaking timeline was essentially a non-answer.
FERC chose a different weapon: Section 206 of the Federal Power Act, which allows the Commission to act when it preliminarily finds that existing tariffs may be unjust and unreasonable. The June 18 orders did exactly that, issuing a preliminary finding against all six RTOs/ISOs and giving each one 60 days to either defend their current tariff or propose revisions.
This approach offers FERC several significant advantages. First, speed. A 60-day compliance window is measured in weeks, not years. Second, regional precision. Rather than imposing a single national interconnection framework that would inevitably fit no one perfectly, FERC issued tailored orders that acknowledge the different market designs, transmission structures, and planning responsibilities across its six jurisdictional regions. Third, legal durability. By anchoring the action in Section 206 and scoping it strictly to FERC-jurisdictional transmission, the Commission minimizes the surface area for state-level legal challenges that might otherwise target a sweeping national rulemaking.
The result is a faster, more targeted, and more legally resilient path to reform, at the cost of some uniformity. As we will argue below, that cost may be lower than it appears, because one RTO has already done the hard work of designing a framework that FERC has explicitly praised as a model.
The SPP HILLS Framework: What It Is and Why FERC Loves It
Southwest Power Pool was not waiting for FERC to act. In September 2025, SPP’s board approved Revision Request 696, creating the High Impact Large Load (HILL) study process and the High Impact Large Load Generation Assessment (HILLGA) process. FERC accepted the tariff revisions on January 14, 2026, with an effective date of January 15, 2026, making SPP the first RTO/ISO in the country to implement a purpose-built large load interconnection framework.
The HILL framework has three core components that work together as an integrated system.
The HILL Definition and Study Process. A High Impact Large Load is defined as a new or increased commercial or industrial load at a single site that reaches either 10 MW or more on transmission systems at or below 69 kV, or 50 MW or more on systems above 69 kV. Once a load qualifies as a HILL, it is subject to enhanced transmission system impact studies and ongoing operational requirements designed to give SPP early visibility into system constraints and coordinate the load’s real-time behavior with grid operators. The goal is to replace the reactive, case-by-case evaluation that previously governed large load requests with a structured, predictable process that surfaces reliability issues before they become crises.
The HILLGA Process. The HILLGA is an optional but powerful mechanism that allows a large load customer to pair its HILL with a new generating resource through an expedited, serial interconnection study process. The key insight here is that large load customers who bring their own generation can bypass the traditional interconnection queue, which in most RTOs is backlogged by years of prior requests. Under HILLGA, the paired study can be completed in as few as 90 days. FERC found that the HILLGA’s eligibility requirements are appropriately structured to deter speculative interconnection requests while still delivering the speed that large load customers need.
Load Limited Resource Interconnection Service (LLRIS). HILLGA-paired generating resources qualify for a new service called LLRIS, which limits the interconnection service to the amount necessary to serve the associated HILL and requires the generator to be in close proximity to the load. This is the “bring-your-own-generation” model: the large load customer builds or contracts for dedicated generation nearby, connects through the expedited HILLGA process, and takes service under LLRIS rather than competing for capacity in the broader transmission queue.
FERC’s response to all of this was notably enthusiastic. Its own June 18 fact sheet called SPP out by name, stating that “SPP stands out with its High Impact Large Load and High Impact Large Load Generation Assessment processes, which are expedited frameworks created to reliably serve massive new power demand from large loads such as data centers.” Commissioner Rosner’s concurrence on the January 2026 SPP approval went even further, explicitly calling on “other transmission providers across the country to consider similar proposals through FPA section 205 filings.” That is about as direct a policy signal as FERC sends.
The SPP HILLS framework effectively pre-solves three of the five reform categories FERC identified in its June 18 show cause orders: an efficient study process with a clear timeline, a co-location and behind-the-meter framework through HILLGA and LLRIS, and new service options for flexible large loads. It is the closest thing to a FERC-blessed template that exists in the market today.
The Case for HILLS as the De Facto National Template
Given the 60-day deadline and the absence of any comparable FERC-approved framework, the remaining five RTOs/ISOs face a straightforward calculus: develop a large load interconnection framework from scratch in two months, or adapt an existing one that FERC has already scrutinized and approved.
The 60-day window effectively forecloses the from-scratch option. Stakeholder comment processes alone, which RTOs/ISOs typically use to develop tariff revisions, routinely take longer than 60 days. MISO, CAISO, ISO-NE, and NYISO could try to file a justification for their existing tariffs rather than propose revisions, but given FERC’s preliminary finding that existing tariffs are unjust and unreasonable, a pure defense filing carries significant risk of rejection and a subsequent directed compliance order.
The HILLS framework, by contrast, already checks the boxes. It has a defined large load threshold, an expedited paired study process with a clear 90-day timeline, a mechanism for bring-your-own-generation, cost protections for existing ratepayers, and ongoing operational requirements. FERC has already reviewed it, asked for and received corrections to ministerial errors, and accepted it as just and reasonable. For a regional compliance team working against a 60-day clock, that record is invaluable.
The question, then, is not really whether MISO, CAISO, ISO-NE, and NYISO will draw on the HILLS framework. They almost certainly will. The question is how they will adapt it to fit the distinct characteristics of their regions. And here the answers are genuinely interesting.
How Each Region Will Likely Adapt the HILLS Model
FERC’s June 18 orders explicitly preserved regional flexibility, acknowledging that the six RTOs/ISOs differ in market design, geography, and planning responsibilities and leaving room for each to define large loads and operational requirements in ways particular to their region. That flexibility is not just polite language. It reflects the real structural differences that will force meaningful divergence from the SPP template.
MISO: Cost Allocation Politics Will Drive the Biggest Changes
MISO spans a massive footprint from Manitoba to Louisiana, with an extraordinarily diverse set of transmission owners, state commissions, and load-serving entities. The HILLS framework’s bring-your-own-generation model will translate reasonably well into MISO’s territory, where land for new generation is available across much of the footprint and MISO already has experience with large load interconnection in its queue.
The adaptation challenge for MISO is almost entirely about cost allocation. MISO uses a multi-zone, multi-Value Transmission Planning (MVP) structure that distributes transmission upgrade costs across its membership in complex ways. SPP’s HILLS framework assumes that large load customers bear the costs of network upgrades needed to serve their HILL, with limited cost shifting to other customers. In MISO, determining which upgrade costs are attributable to a specific HILL versus which flow through the broader MVP cost allocation mechanism will require careful tariff language and will generate significant pushback from existing members who see large load growth as a threat to their transmission cost allocations.
MISO will also likely need to address the distinction between its North and South transmission regions, which operate under different planning frameworks and have different levels of transmission constraint. Expect MISO’s filing to propose a HILLS-adjacent process with a 90-day study timeline, but with more elaborate cost allocation provisions and potentially different load thresholds for its northern versus southern footprint.
CAISO: A Structural Rebuild, Not Just an Adaptation
CAISO is the most structurally distinct of the six RTOs/ISOs, and adapting HILLS for California will require more than filing new tariff language. CAISO does not offer traditional Order No. 888 open access transmission service. Instead, transmission access in CAISO is bundled into the utility distribution company structure, with the large investor-owned utilities, particularly PG&E, SCE, and SDG&E, retaining significant roles in transmission planning and service. This fundamentally changes the procedural architecture of any large load interconnection process.
The HILLGA’s bring-your-own-generation model also faces physical constraints in California that simply do not exist in SPP. Siting new generating resources in California involves CPUC resource planning approval, local air district permitting, and some of the most contested land use processes in the country. The 90-day study timeline is achievable on the transmission study side; it is much less achievable on the generation development side. CAISO’s adaptation will likely need to incorporate a “pre-approved generation zone” or similar concept that allows large load customers to access HILLGA-equivalent expedited study processes for generation in designated areas where siting is already substantially complete.
CAISO’s filing will also need to address the CPUC’s role carefully. California’s state regulatory structure gives the CPUC oversight over retail rates and integrated resource planning that FERC does not have in most other states. Any large load tariff that affects retail rate design or resource adequacy obligations will need to be coordinated with CPUC proceedings, adding a layer of complexity that SPP, operating primarily in states with less aggressive state-level energy regulation, did not have to navigate.
ISO-NE: Capacity Market Integration Is the Central Problem
ISO New England operates in one of the most physically constrained grid territories in the country, with limited transmission import capability into key load centers and generation largely concentrated in certain areas. The bring-your-own-generation model that makes HILLS so attractive in SPP is much harder to execute in New England, where transmission constraints mean that a generating resource “nearby” a large load in geographic terms may still face significant congestion barriers.
ISO-NE’s most significant adaptation challenge is the Forward Capacity Market (FCM). New generation resources seeking to serve a HILL under a HILLGA-equivalent process would typically need to clear the FCM to ensure resource adequacy. But the FCM’s annual auction cycle means that a generating resource developed on a HILLGA-equivalent timeline could face a multi-year gap between project development and capacity market participation. ISO-NE’s filing will likely need to propose either a separate capacity commitment pathway for HILL-paired generation or a modification to the FCM that allows HILL-paired resources to make binding capacity commitments outside the standard auction cycle.
ISO-NE also operates in a region where state policies, particularly in Massachusetts, Connecticut, and Rhode Island, have significant influence over energy procurement and carbon policy. Any large load framework that is perceived as potentially increasing fossil fuel generation to serve data centers will face political friction at the state level, even if FERC has jurisdictional authority. ISO-NE’s adaptation will need to either incorporate carbon considerations into the HILLGA-equivalent process or explicitly carve out the issue as a state policy matter.
NYISO: Urban Load Centers and Transmission Constraints Complicate Everything
New York faces many of the same challenges as ISO-NE, but with the added complexity of serving some of the densest and most constrained load centers in the country. New York City and Long Island are effectively electrical islands, connected to the rest of the state through a limited set of high-voltage transmission corridors. Large load growth in or near these areas cannot be served by nearby generation in the way HILLS contemplates, because there is simply no room to site significant new generation in urban New York.
NYISO’s adaptation will likely focus the HILLGA-equivalent process on upstate New York, where land for new generation is available and transmission constraints are less severe. For downstate large load requests, NYISO may need to propose an alternative pathway that relies on demand response commitments, behind-the-meter storage, or virtual power purchase agreements rather than a co-located generation model.
New York also has an active Climate Leadership and Community Protection Act (CLCPA) compliance process, administered by the NYSPSC, which sets binding targets for renewable energy and carbon emissions. NYISO’s large load framework will need to navigate whether HILL-paired generation must qualify as clean energy under CLCPA standards or can be any fuel type, a question that FERC does not have jurisdiction to answer but that will significantly affect the practical implementation of any NYISO HILLS equivalent.
What to Watch in the Next 60 Days
The 60-day compliance window runs through mid-August 2026. During that period, each of the six RTOs/ISOs will develop and file their responses, and interested parties will have 30 days to respond to each regional filing. A few dynamics are worth watching closely.
First, whether SPP files a defense or proposes further enhancements. SPP’s existing HILLS framework is already FERC-approved, but the show cause order still required a response. SPP may use the opportunity to file targeted enhancements that address any gaps FERC identified in the June 18 order, potentially setting an even higher bar for the other regions to match.
Second, the degree to which the other five RTOs/ISOs coordinate their filings. There is nothing in the show cause orders that prevents RTOs/ISOs from sharing drafts or developing parallel provisions, and it would be somewhat surprising if their legal and regulatory teams were not already in contact. Coordinated filings would reduce the risk of inconsistent FERC treatment and could accelerate the development of something approaching a de facto national standard.
Third, the fate of non-RTO/ISO utilities. FERC’s show cause orders were explicitly limited to the six RTO/ISO regions under its jurisdiction. ERCOT, which operates largely outside federal jurisdiction, is unaffected. Non-RTO utilities operating under traditional FERC-jurisdictional tariffs received only a suggestion from FERC that they consider voluntary Section 205 filings. Whether those utilities step forward, and on what timeline, will shape the completeness of any national large load interconnection reform.
The grid is changing faster than the regulatory structures designed to govern it. FERC’s June 18 action is an ambitious attempt to close that gap, and the SPP HILLS framework is the most important policy innovation in the field right now. The next 60 days will tell us how well the rest of the country can adapt it.