NERC security rules [PDF], that were updated and became mandatory last week, might well become "a new PCI DSS" and trigger "a golden age" of security in the energy industry: the rules are mandatory, they are specific (more specific than a lot of other regulatory security guidance) and there is an enforcement body (NERC) that can make life miserable for those not complying.
Here are some log-related examples from the guidance:
"R5.1.2. The Responsible Entity shall establish methods, processes, and procedures
that generate logs of sufficient detail to create historical audit trails of
individual user account access activity for a minimum of ninety days. "
"R6.4. The Responsible Entity shall retain all logs specified in Requirement R6 for ninety calendar days.
R6.5. The Responsible Entity shall review logs of system events related to cyber security
and maintain records documenting review of logs. "
So, again: have logs, retain them ("Top 11 Reasons to Collect and Preserve Computer Logs") and review them ("Top 11 Reasons to Look at Your Logs").