# Reserve margin. **Citation:** 199 IAC 19.15 **Type / status:** regulation / current **Agency:** Iowa Utilities Commission **Effective:** 2025-07-16 **Published:** 2026-08-19 19.15(1) Applicability. All rate-regulated gas utility companies may maintain a reserve of contract services in excess of their maximum daily system demand requirement and recover the cost of the reserve from their customers through the PGA. 19.15(2) Definitions. The following definitions apply to t ## Document text 19.15(1) Applicability. All rate-regulated gas utility companies may maintain a reserve of contract services in excess of their maximum daily system demand requirement and recover the cost of the reserve from their customers through the PGA. 19.15(2) Definitions. The following definitions apply to the terms as used in this rule: "Contract services" refers to the amount of firm gas delivery capacity or delivery services contracted for use by a utility to satisfy its maximum daily system demand requirement, including the planned delivery capacity of the utility-owned liquefied natural gas facilities but excluding the delivery capacity of propane storage facilities. "Design day" means reasonably anticipated colder-than-normal weather conditions during a 24-hour period beginning at 9 a.m. "Maximum daily system demand requirements" means the maximum daily gas demand requirement that the utility forecasts to occur on behalf of its system firm sales customers under design day weather conditions. The maximum daily gas demand requirement forecast will be determined based upon an evaluation of historic usage levels of firm sales customers, adjusted for reasonably anticipated colder-than-normal weather conditions and other clearly identifiable factors that may contribute to the demand for gas by firm sales customers. The maximum daily system demand requirements shall be submitted for approval by the commission with the Annual PGA filing required by subrule 19.9(2). 19.15(3) Maximum daily system demand requirements of less than 25,000 Dth per day. A reserve margin of 9 percent or less in excess of the maximum daily system demand requirements will be presumed reasonable. 19.15(4) Maximum daily system demand requirements of more than 25,000 Dth per day. A reserve margin of 5 percent or less in excess of the maximum daily system demand requirements will be presumed reasonable. 19.15(5) Rebuttable presumption. All contract services in excess of an amount needed to meet the maximum daily system demand requirements plus the reserve are presumed to be unjust and unreasonable unless a factual showing to the contrary is made during the periodic review of gas proceeding or in a proceeding specifically addressing the issue with an opportunity for an evidentiary hearing. All contract services less than an amount of the maximum daily system demand requirements plus the reserve are presumed to be just and reasonable unless a factual showing to the contrary can be made during the periodic review of gas proceeding or in a proceeding specifically addressing the issue with an opportunity for an evidentiary hearing. 19.15(6) Allocation of cost of the reserve. Fifty percent of the reserve cost shall be collected as a demand charge allocation to noncontractual firm customers. The remaining 50 percent shall be collected as a throughput charge on customers excluding transportation customers who have elected no system supply reserve. ## Provenance - Official: Yes - Source: - Source ID: `ia-legislature-pipeline-safety` - SHA-256: `4e6ede0a1ef1c54c1ac6bffadbd42d3b0fa8e794c32be1e4fc6394e341428720` - Retrieved: 2026-08-20T08:17:15.771Z - Exported: 2026-08-25T01:09:06.243Z - Document slug: `ia-iac-199-19-15` ### Source metadata ```json { "jurisdiction": "US-IA", "chapter": "199 IAC chapter 19", "exactScope": "This bounded corpus contains every current rule in 199 IAC chapters 10 and 19, the two chapters identified by the Iowa Utilities Commission pipeline-safety page, plus 15 selected Iowa Code sections that directly establish gas-utility applicability, inspection and rulemaking authority, enforcement, penalties, and acceptance of federal pipeline-safety aid. It does not claim all Iowa pipeline law or all of Iowa Code chapters 476 and 479.", "excludedScope": "Excluded are hazardous-liquid safety (which the IUC says remains exclusively with PHMSA), hazardous-liquid permitting in 199 IAC chapter 13 and Iowa Code chapter 479B, damage prevention and one-call law, agricultural restoration chapter 9, railroad-crossing chapter 42, general procedure and filing chapters, permits/orders/forms, privately owned propane service, and federal or private incorporated text. Former 199 IAC chapter 12 is inventoried as repealed and is not searchable.", "applicabilityCaveat": "Applicability depends on IUC jurisdiction, public-utility or pipeline-company status, intrastate versus interstate status, the gas and facility involved, customer count, rate regulation, exemptions, federal preemption, waivers, permits, tariffs, and Commission orders. Iowa inspects interstate gas operators only as PHMSA's agent; federal authorities retain enforcement. Chapter 19 is limited to rate-regulated gas utilities except where another law or order extends a duty.", "incorporationCaveat": "The rules incorporate or reference 49 CFR Parts 191, 192, 193, and 199; ASME B31.8-2022; NFPA 59-2024, NFPA 54-2024, and NFPA 501A-2021; other Iowa rules and statutes; federal forms and interpretations; and utility tariffs. The connector records citations but does not reproduce incorporated federal or private material, decide which edition controls beyond the state text, or grant rights in private standards.", "publicationCaveat": "The current IAC chapter listings dated August 5, 2026 are used to prove chapter and rule inventory; their official PDF and DOCX-formatted 'RTF' artifacts are archived independently. The official 2026 Iowa Code was published December 22, 2025. The live 2026 Code & Acts Sections Amended report is provisional; signed HF 2799 sections 23 and 24, effective July 1, 2026, are preserved as overlays to selected sections 476.1B and 476.2. Any unexpected selected-section amendment causes refresh failure.", "rights": "Iowa legal text and other government edicts are preserved with official attribution and cryptographic provenance. Public access does not grant rights in agency seals, website presentation, forms, utility filings, incorporated federal compilations, or privately authored standards; redistribution of those materials requires a separate rights review.", "references": [], "sourceHistory": "[ARC 9351C, IAB 6/11/25, effective 7/16/25]", "region": "IA" } ```