As prescribed in section 4.2 and 4.3 of the Tiered Rate Methodology (TRM), the Rate Period High Water Mark (RHWM), the RHWM Tier 1 System Capability (RT1SC), and Above-RHWM Loads are set by BPA in the RHWM Process prior to each power rate proceeding. The RHWM sets the maximum planned amount of power that a customer may purchase each year of the Rate Period under Priority Firm Tier 1 Rates.

FY 2026-2028 RHWM Process Materials

Historical RHWM Processes