City officials say a "rogue" race to replace the canceled Boulder Marathon on Sunday would be illegal and dangerous.

The Daily Camera reports the idea of the replacement race has become popular with some runners, and at least several people are planning to meet at the Boulder Reservoir on Sunday morning.

Mike Eubank, Boulder's project manager for special events, points out that a race or event involving 50 or more people must be sanctioned. No permits for a Sunday race have been issued.

Boulder Marathon director Jeff Mason canceled the original race, saying he couldn't get the permits because of changes to the course made after a death at a half marathon in Boulder in May.

The decision angered many who had paid their entry fees. Up to 2,000 people were expected to run.

More From ESPN Western Colorado