The treasurer after being appointed by the board of directors shall qualify by making an oath that he will well and truly perform his duties as such treasurer and by entering into a bond to the state of New Mexico conditioned the same as the bonds of county treasurers. Said bond to be in a sum to be fixed by the board of directors, but such bond shall be not less than the sum of twenty thousand ($20,000) dollars, to be signed by a surety company, authorized to do business in this state, and to be approved by the board of directors and the district judge of the district in which the office of said irrigation district is located. Said treasurer shall receive a salary fixed by the board of directors not exceeding the rate of fifteen hundred ($1,500) dollars per annum, and shall hold his office at the pleasure of the board or [of] directors; provided, however, that in the event one person is appointed to all the offices of assessor-collector and treasurer, only one bond need be furnished in such sum as may be fixed by the board of directors, subject to the approval of the district judge of the district in which the office of the irrigation district is located.