Neither this chapter nor any rules adopted hereunder shall prohibit the continuance of the lawful use of any building, premises, or land for any trade, industrial, residential, or other purpose for which the building, premises, or land was used on October 1, 1964, or at the time any rule adopted under authority of this part takes effect. All such existing uses shall be nonconforming uses. Any land identified as a kuleana may be put to those uses which were historically, customarily, and actually found on the particular lot including, if applicable, the construction of a single family residence. Any structures may be subject to conditions to ensure they are consistent with the surrounding environment.