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Committee working material

Imperial County 20 MW Scale-and-Siting Framework

Desktop working paper | September 18, 2026

The policy choice

Imperial County should regulate projects by the load IID can actually evaluate and serve, not by a hypothetical 300-330 MW campus. IID’s current Large Load Tariff applies to a customer requesting at least 20 MW with an 80% minimum load factor. That makes 20 MW a defensible planning unit, but not a promise of available capacity at any site. Every candidate still requires an IID system-impact, facilities, power-supply and interconnection determination.

Proposed scale framework

Tier Load County path Required showing
1. Standard / fast path <5 MW Existing industrial process; administrative review where zoning allows Utility will-serve; parcel control; ordinary water, noise, fire and generator compliance; no phased scheme designed to evade aggregation
2. Intermediate 5 to <20 MW Staff-level infrastructure screen, then conditional use review IID pre-application letter; feeder/substation screen; annual and peak water budget; sewer plan; generator/BESS noise and air analysis; community separation; construction phasing
3. Large-load planning unit 20 to <50 MW Full large-load track coordinated with IID IID tariff compliance; applicant-funded studies/upgrades and financial security; firm deliverable capacity and energy; curtailment terms; redundant service plan; independent water-budget review; emergency-power operating limits; heat/noise/fire plan; enforceable milestones
4. Campus / system-scale 50 MW+ or aggregated common-control phases Specific plan or development agreement plus full environmental and cumulative review Everything above, plus transmission and generation plan, portfolio/resource adequacy, cumulative water/air/land impacts, proof of capital, phased approvals with expiration, and no entitlement beyond demonstrated power

Anti-evasion rule: aggregate adjacent parcels, affiliates, shared substations and phased buildings under common control. A 100 MW campus is not five unrelated 20 MW projects.

Pass/fail gates for a 20 MW site

  1. Power: IID identifies a feasible point of interconnection, deliverable MW and MWh, upgrade scope, schedule, curtailment priority and applicant cost. Line proximity alone does not pass.
  2. Water: independently reconciled potable, process/cooling and fire-flow budgets. Prefer air or closed-loop cooling; identify the actual water purveyor and legally available supply.
  3. Land compatibility: industrial entitlement or a clear entitlement path; adequate acreage, drainage and road access; separation from homes, schools, hospitals and incompatible agricultural operations.
  4. Backup generation: disclose MW, fuel, annual test/run hours, emissions, noise and fuel storage. Large engine farms near housing or light-industrial neighbors fail even if emergency-only on paper.
  5. Developer proof: parcel control, financing evidence, equipment deposits, schedule, and security for IID/county costs before public money or capacity is reserved.
  6. Verification after opening: revenue-grade interval meter, annual water and generator-hour reporting, noise/air testing, permit audit rights, enforceable load ramp, decommissioning security and automatic expiration for missed milestones.

First-pass six-site screen

These are study areas, not recommended parcels and not findings of available 20 MW service.

Gateway of the Americas, east Calexico port

Why screen it
1,775-acre planned industrial area; IID completed a Gateway Substation expansion in 2026 for industrial/commercial growth
Land/use and compatibility
Large industrial setting and border/logistics access; map buffers to Calexico housing, port/security uses and Alamo River
Water
Confirm service capacity and industrial allocation; older plan is not proof of present water
Generation implication
Industrial setting is better than a residential edge, but engine count/noise/air still need a parcel buffer
First fatal-flaw question
Can IID deliver a firm 20 MW block after committed Gateway growth, and can the local water/sewer systems serve it?

Imperial Industrial Park / Imperial Substation area

Why screen it
121 acres marketed as industrial-zoned; historical 92-kV Imperial Substation record
Land/use and compatibility
Reuse of a former cotton-processing/industrial site is preferable to greenfield; verify parcel ownership, active tenants, nearest residences and airport constraints
Water
Identify current purveyor, fire flow and cooling supply; marketing page gives no capacity proof
Generation implication
Existing industrial use may reduce conflict, but on-site generation should be sited at the interior with modeled noise/air
First fatal-flaw question
Is there a parcel with both control and a feasible 20 MW IID interconnection without displacing productive industry?

Luckey Ranch / Brawley industrial area

Why screen it
Historical 45.24-acre M-1/light-industrial plan; Brawley has a 92-kV substation/line corridor
Land/use and compatibility
Industrial designation and acreage are promising; screen distance to Brawley homes, airport, rail and agricultural operations
Water
Confirm City of Brawley water/wastewater capacity and drought/fire-flow constraints
Generation implication
Avoid the city edge for a full engine yard; BESS plus limited emergency generation may fit better
First fatal-flaw question
Which parcel is close enough electrically but far enough from homes, and what headroom exists at Brawley?

Mesquite Lake / Keystone Specific Plan

Why screen it
About 5,100 acres planned for light, medium and heavy industry, offering room for buffers
Land/use and compatibility
Strong land-use concept and scale; however the plan itself says major infrastructure is limited and needs substations, water/sewer, roads and drainage
Water
A reclamation facility was planned at 2.5 MGD initial/15 MGD ultimate, but current existence/capacity is unverified
Generation implication
Large buffers make backup generation more manageable, but infrastructure creation could erase the site’s advantage
First fatal-flaw question
Has the water/reclamation and electric infrastructure actually been built, and who pays to bring 20 MW to a parcel?

Holtville industrial/substation area

Why screen it
Existing Holtville substation and a permitted 100-MW BESS show a meaningful grid node
Land/use and compatibility
Vacant/light-industrial land exists, but the BESS record and local reporting identify nearby homes and a high school. Use only parcels with a demonstrable buffer
Water
Confirm city water/sewer and fire flow; no desktop capacity proof
Generation implication
This is the clearest warning site: a large generator yard near homes/school should fail compatibility even if the grid works
First fatal-flaw question
Is there a different parcel on the node with adequate separation, or should Holtville be excluded?

Niland/Calipatria geothermal-generation corridor

Why screen it
Existing Niland generation and project records showing a nearby IID 230-kV corridor make this a logical grid-oriented screen
Land/use and compatibility
Rural/energy landscape can provide buffers; evaluate Salton Sea, geothermal, habitat, flood, seismic, air-quality and environmental-justice constraints
Water
Potable/process supply is likely the hard gate; test reclaimed/non-potable options and avoid open-loop cooling
Generation implication
Better physical separation for engines, but cumulative air burden and disadvantaged-community impacts matter
First fatal-flaw question
Can IID identify deliverable load at a suitable node, and is there a lawful low-water cooling/fire plan?

Control case: the Aten/Clark corridor

The Aten/Clark proposed-campus corridor is electrically relevant because the applicant’s study identifies IID’s 230-kV S line and 92-kV R line. It is treated here as a control case, not as a presumed-suitable site: an open question for the committee is whether a smaller 20 MW phase on a better-buffered parcel resolves the land-use conflict. Applicant-hosted feasibility material is not an IID will-serve commitment.

Claims awaiting verification

The following circulating claims are unverified and should be treated as open questions, not established facts:

Proposed committee action

Direct staff and IID to return with a 20 MW suitability atlas: six to ten study areas, parcel-level buffers, existing zoning, distance to 92/161/230-kV facilities, water purveyor and capacity, flood/airport/habitat constraints, and IID’s red/yellow/green feasibility status. Publish the methodology, not customer-confidential system details. The atlas should show where a right-sized project could work and what evidence any applicant must provide before the County spends time on a proposal.

Sources

Source file: view in the public committee library