Mont. Code Ann. § 7-12-4334

All money derived from the collection of the assessment provided for in the resolution required by 7-12-4333 shall be paid into a fund known as the special improvement lighting district No..... maintenance fund, the number of which shall correspond with the number of the lighting district, for the maintenance of and the supplying of current for which the tax is levied. Such fund shall be used to defray the expense of maintaining and furnishing electrical current for the lights in said district and for no other purpose.