Back in February, the U.S. Supreme Court stayed implementation of the Environmental Protection Agency’s Clean Power Plan (CPP) pending resolution of various legal challenges against the rule. The CPP, which mandates an approximately 30 percent reduction in greenhouse-gas emissions from power plants, had been the subject of much controversy due to concerns that it could result in plant closures that would imperil the nation’s electric reliability.

Since the stay, lots of folks who were concerned about the CPP have turned their attention elsewhere, thinking that the problem is at least on hold. But that is a mistake. While undoubtedly important, the CPP is only one of a number of different EPA rules that could affect electric reliability. Many of these rules have overlapping effects, such that most of the plant closures anticipated as a result of the CPP will still occur even if the rule never goes into effect.

Take, for example, the EPA’s Regional Haze rule, which focuses on power-plant emissions that may impair visibility. Last fall, the Electric Reliability Council of Texas (ERCOT), which manages the Texas electrical grid, put out an analysis looking at the impact of the Regional Haze rule in the state. According to ERCOT’s analysis, complying with the Regional Haze rule would require plants producing 3,000 megawatts of power to install expensive new scrubbers, while an additional 5,000 megawatts would need to upgrade existing scrubbers. A significant proportion of these plants might shut down instead of undergoing these costly upgrades. ERCOT concluded that the “Regional Haze requirement would have a significant local and regional impact on the reliability of the ERCOT transmission system.”

Regional Haze is not the only other EPA regulation that could lead to power-plant closures. The EPA’s new ozone standards, the Cross State Air Pollution Rule and other rules in the process of implementation all impose costly requirements on many existing power plants. The cost to comply with any one of these rules could force plants into closure. The cumulative impact of these rules could rival the impact of the CPP.

States therefore cannot simply assume that the stay of the CPP means a return to business as usual.