There are transmission paths within the Rocky Mountain area, (Colorado and Wyoming), that have been identified as limiting the ability to freely schedule generation. These paths in the Rocky Mountain area have been historically labeled as TOTs, which is shorthand for the TOTal flow on a specified grouping of transmission lines. A graphical representation of the TOTs within the Rocky Mountain area can be found in the Transmission Map area.

The TOTs in the Rocky Mountain area have all been formally assigned a transfer capability, based on rigorous technical studies with the participation of all affected utilities. These TOTs have formal operating procedures that define the transfer capability under both normal and abnormal operating conditions. The transfer capability of the TOT is allocated among the various path owners.

TOT 1 defines the transfer capability between Colorado and Utah to the west. TOT 2A defines the transfer capability between Colorado and New Mexico to the south. TOT 3 defines the transfer capability from Wyoming/Nebraska in the north to Colorado. There are no transmission lines east from Colorado/Wyoming/Nebraska because this is the asynchronous boundary between the Eastern Interconnection and the Western Interconnection. There are two back-to-back DC ties between the Eastern and Western Interconnections at Sidney (Nebraska) and Stegall (Nebraska.)

Within Colorado, TOT 5 separates Colorado on a north-south line that conceptually follows the Continental Divide. TOT 7 cuts the transmission lines funneling into the Denver metro area from the north.

TOTs 4A and 4B define the transmission capability southwest and north out of Wyoming. These paths are not posted in the Rocky Mountain Area Oasis, but may be found with PacifiCorp.

The participants in the Rocky Mountain Area Oasis use the Western System Coordinating Council (WSCC) Rated System Path Method, as described in the NERC document titled "Report on Available Transmission Capability Definitions and Determinations." The paths that have been identified and rated are included in the WSCC document titled "Path Rating Catalog." The ATC postings by the participants in the Rocky Mountain Area Oasis also conform to the principles contained in the document titled "Determination of Available Transmission Capacity within the Western Interconnection" jointly published by WSCC and the three RTGs within WSCC. The documents referenced above can be obtained from either WSCC or NERC. The intent is to comply with all NERC, WSCC, RTG, and FERC rules regarding TTC and ATC.

Additional information regarding TOTs 1, 2A, 3, 5, and 7 is available to authorized users of this site by clicking on the "Transmission Information" link available on each provider's home page.