Allstream Insiders Summary
Tallgrass and Bridger Pipeline have launched concurrent 30-day binding joint-tariff open seasons for crude oil transportation from Bridger’s Guernsey Hub in Wyoming on the Tallgrass-operated Pony Express Pipeline and Seahorse Pipeline.
Both open seasons began August 21, 2026 and offer incentive tariff rates in exchange for shipper commitments. Tallgrass said each offering will use existing pipeline capacity.
The two announcements do not identify the amount of capacity being offered, the required commitment volume or term, the incentive rates, prospective shippers or the individual destinations included in the programs. Tallgrass said qualified parties can review the commercial terms after executing a confidentiality agreement.
The existing-capacity language is important for contractors and suppliers. These open seasons are commercial transportation offerings and should not be characterized as final investment decisions, pipeline expansions or construction awards. Tallgrass did not announce new pipe, pump stations, terminals, capital spending or a construction schedule in connection with the August offerings.
Tallgrass Open Season Comparison
| Open season | Origin | Transportation system | Commercial structure | Announced duration | Infrastructure status |
|---|---|---|---|---|---|
| Pony Express Pipeline | Bridger’s Guernsey Hub, Wyoming | Tallgrass Pony Express Pipeline and Bridger Pipeline joint tariff | Binding shipper commitments in exchange for incentive tariff rates | 30 days beginning August 21, 2026 | Uses existing capacity |
| Seahorse Pipeline | Bridger’s Guernsey Hub, Wyoming | Seahorse Pipeline and Bridger Pipeline joint tariff | Binding shipper commitments in exchange for incentive tariff rates | 30 days beginning August 21, 2026 | Uses existing capacity |
Tallgrass issued the Seahorse announcement at 4:00 p.m. Mountain time and the Pony Express announcement 15 minutes later. The operative language in the releases is otherwise substantially the same, but each applies to a different Tallgrass-operated carrier and tariff offering.
What Are Tallgrass and Bridger Offering Shippers?
Tallgrass and Bridger are seeking binding crude oil transportation commitments from the Guernsey Hub under two separate joint-tariff programs. Prospective shippers may choose between transportation involving Pony Express or Seahorse, subject to the detailed terms made available through Tallgrass’s confidentiality process.
An open season is the formal period during which a pipeline operator solicits shipper commitments under disclosed commercial terms. In these announcements, Tallgrass uses the word “binding” to describe the offerings and the commitments being sought. The public releases do not provide enough information to determine the minimum volume, contract term, rate or allocation procedure for either August program.
The incentive-rate structure is a commercial mechanism for attracting committed volumes. It does not, by itself, establish that Tallgrass will expand either pipeline. Both releases expressly state that the service will use existing capacity.
Where Does Pony Express Transport Crude Oil?
Pony Express transports crude oil from the Guernsey, Wyoming, area and northeastern Colorado to destinations in Kansas and Oklahoma, including the Cushing market. Tallgrass describes the system as an approximately 900-mile pipeline extending from Wyoming and southeastern Colorado to Cushing, with refinery connectivity along the route.
Tallgrass’s current system information lists 230,000 barrels per day of capacity out of Guernsey and another 90,000 barrels per day from Northeast Colorado Lateral receipt points to the Cushing area. Those are system-capacity figures; Tallgrass did not state how much Pony Express capacity is available through the August open season.
The system information identifies delivery connectivity at Ponca City and multiple Cushing-area terminals and pipeline systems. The August announcement refers more generally to crude oil transportation from Bridger’s Guernsey Hub and does not specify which Pony Express destinations are included in the incentive-rate program.
What Is the Current Seahorse Pipeline Route?
Tallgrass’s current Seahorse tariff covers crude oil transportation from origins in Wyoming and Colorado to destinations in Kansas and Oklahoma. The tariff lists Guernsey-area origins and destinations that include Augusta and McPherson, Kansas; Ponca City, Oklahoma; and multiple terminals and pipeline connections in the Cushing area.
The Seahorse and Bridger joint tariff also provides transportation paths from origins in North Dakota, Montana and Wyoming to points in Kansas, Oklahoma and Wyoming. The August open season is narrower in its public description: it begins at Bridger’s Guernsey Hub and uses existing Seahorse capacity.
Seahorse’s current tariffed service should not be confused with Tallgrass’s 2018 proposal for a new pipeline from Cushing to Louisiana. The August 2026 announcement does not refer to a Gulf Coast route, a new long-haul pipeline or the Plaquemines liquids-terminal concept associated with that earlier proposal.
How Do the August Open Seasons Differ From the February Offerings?
Tallgrass and Bridger’s February 2026 open seasons sought commitments for expansion capacity from Bridger’s North Dakota origins, while the August offerings begin at Guernsey and use existing capacity. Keeping the two rounds separate avoids turning the current commercial programs into an unsupported expansion announcement.
The February Pony Express and Seahorse releases stated that the carriers would determine total expansion capacity based on commitments secured during those open seasons. The August releases contain no comparable expansion language and do not report the outcome of the February programs.
Tallgrass also conducted a separate Pony Express open season in June 2026 for crude transportation from Colorado origins using existing capacity. Together, the announcements show continued commercial marketing across different receipt points and tariff paths, but they do not establish that new facilities have been approved.
What Do the Open Seasons Mean for the Midstream Supply Chain?
The immediate opportunity is for crude oil shippers seeking contracted transportation and incentive rates—not an announced construction package for pipeline contractors. Because Tallgrass is marketing existing capacity, the releases do not support claims of new pipeline mileage, pump-station construction, terminal expansion or equipment procurement.
Higher committed utilization could eventually affect operating, scheduling, measurement, integrity and maintenance requirements across the connected systems. Tallgrass has not announced additional work in those areas, however, so any supplier implications remain conditional rather than confirmed opportunities.
For contractors and manufacturers, a stronger capital signal would require a later announcement identifying expansion capacity, new facilities, a capital budget, regulatory filings, procurement packages or a construction schedule. None of those items appears in the August 21 releases.
Allstream Insiders Perspective
Tallgrass and Bridger’s coordinated open seasons provide a clear commercial signal: the companies are marketing two tariff paths from the Guernsey Hub and are prepared to offer incentive rates for binding shipper commitments.
The announcements are less significant as construction indicators. By specifying existing capacity, Tallgrass distinguishes the August programs from an expansion open season. That distinction matters for industrial readers because a transportation commitment on available capacity does not necessarily require new facilities.
The results of the 30-day solicitation will determine whether the programs secure additional committed volumes, but Tallgrass has not said whether it will disclose those results publicly. Until the companies announce a facility expansion or specific capital work, the Pony Express and Seahorse open seasons should be tracked as commercial developments within the existing crude oil transportation network.
