[Petitioners required to pay sums determined by directors.]

The board of directors to whom such petition is presented may require as a condition precedent to the granting of the same that the petitioners shall severally pay to such district such respective sums, as nearly as the same can be estimated by the board, as said petitioners or their grantors would have been required to pay for their pro rata share of all bonds and the interest thereon which may have previously thereto been issued by said district had such lands been included in such district at the time the same was originally formed or when said bonds were so issued; and said board may require such petitioners to pay such further sums as the board may deem just on account of irrigation works or water rights paid for otherwise than by issue of bonds.