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Western Sub-Regional Planning

Utilities plan additions to the transmission and distribution facilities they own that meet their customers’ needs and make sense for their shareholders. Because the grid is interconnected, major additions must be coordinated not only with neighboring utilities but with all utilities in the region, even if the new facilities are located in only one state. Interstate projects must also be planned in ways that support the reliability of the entire grid.

Utilities in every geographic region of the West have formed voluntary Sub-Regional Planning Groups (SPGs) to coordinate this planning. Each Sub-Regional Planning Group maintains a website with information about major projects proposed in its region and the studies being performed to evaluate those projects.

The Sub-Regional Planning Groups include:

• California Independent System Operator (CAISO):
The CAISO plans and operates the transmission system covering about 70% of California, including the transmission facilities owned by Pacific Gas & Electric, Southern California Edison, and San Diego Gas & Electric. It is one of only two Regional Transmission Organizations (RTOs) in the Western Interconnection (the other is the Alberta Electric System Operator). Municipal utilities plan, own and operate transmission in the remainder of the state.
• Sierra Subregional Planning Group (SSPG):
• Southwest Area Transmission (SWAT):
SWAT covers AZ, NM, southern NV and a small portion of southeastern CA. The many work groups shown on the website address projects in specific geographic areas or special transmission problems.
• Colorado Coordinated Planning Group (CCPG):
• Northern Tier Transmission Group (NTTG):
The NTTG footprint includes UT, WY, MT, ID, OR and a small portion of WA.
• Columbia Grid:
The Columbia Grid footprint includes WA, OR, ID, and a small area of MT.
• British Columbia Transmission Corporation (BCTC):
Alberta Electric System Operator (AESO):

At the request of the Western Electricity Coordinating Council (WECC), these Sub-Regional Planning Groups have also recently formed a Subregional Coordination Group (SCG) to coordinate planning across the seams among them.

For an excellent PDF of frequently asked questions – go HERE on WECC’s site.