(1) This rule sets out, for purposes of the review of proposed subdivisions, the requirements for minimum lot or parcel size.

(2) Subject to (4), each proposed new subdivision lot, area proposed for condominiums, or area proposed for permanent multiple spaces for recreational camping vehicles or mobile homes, must be of sufficient size to satisfy all of the following criteria:

(a) facilities on each lot must comply with the setback requirements in ARM 17.36.323, except that setbacks for existing sewage systems may be waived pursuant to ARM 17.36.327(3);

(b) drainfield mixing zones must be located in compliance with ARM 17.36.322(5);

(c) well isolation zones must be located in compliance with ARM 17.36.330(4); and

(d) as shown on the lot layout document, each lot must have adequate space for the sewage treatment system, drainfield replacement area, water supply, and all permanent structures including, but not limited to, driveways, houses, garages, ditches, service lines, easements, and utilities. Easements may be used to satisfy this requirement.

(3) For lots created before July 1, 1973, and for which sanitary restrictions are proposed to be lifted, the requirements of (2)(a) and (d) apply, subject to the provisions of ARM 17.36.106(3).

(4) The reviewing authority may require lot sizes larger than those allowable under (2) if necessary to protect human health or water quality.