Any such irrigation district which shall have entered into any such contract of indemnity with the state of Washington is hereby empowered and shall annually be required to levy assessments against all the property within said district from time to time in such amounts as shall enable it to reasonably anticipate and promptly comply with its said contract with the state of Washington. Such assessments shall be levied and be payable at the time and in the manner that its regular assessments are made and shall have the same validity, force and effect as assessments for any other purposes. Such assessments shall be levied for and shall be paid into a fund to be known as "The Indemnity Fund" and such fund shall not be used for any purpose other than to fulfill its obligations under its indemnity contract with the state of Washington. PROVIDED, That when all expenses, losses or damages for which the district may become liable to the state of Washington under RCW 87.48.010 shall have been paid to the state of Washington any money then remaining in "The Indemnity Fund" shall be transferred to the maintenance fund of said district.