The FCC has issued a Notice of Proposed Rule Making (ET-Docket 12-338) which, among many other things, formally proposes a secondary amateur allocation at 135.7-137.8 kHz. The 130-page notice, whose broad purpose is to implement the decisions of the 2007 World Radiocommunication Conference (WRC-07), also proposed granting primary status to amateur radio on the 1900-2000 kHz segment of the 160-meter band. That segment is currently shared with radiolocation systems. (The 1800-1900 kHz band segment is already allocated exclusively to the Amateur Service.)
The only current U.S. users of the spectrum segment including the proposed 135.7-137.8 kHz band are power companies operating PLC (power line carrier) systems for monitoring electrical infrastructure. Broadband over Power Lines (BPL) is a form of PLC, but the systems at these frequencies are used internally by the power companies. Ironically, if the amateur allocation is approved here, the FCC says it is likely that hams will have to coordinate with utilities and avoid causing interference to the PLC systems.
Comments on ET Docket 12-338 are due 60 days after publication in the Federal Register, with reply comments due 30 days later. As of this posting, the NPRM had not yet been published in the Register.