242.750. In the event that the drainage operations conductedby any such drainage district shall not drain any tract of landtherein to the depth of mining operations conducted on suchtract, necessitating the operation by the owner of such tract orhis agents or lessees or sublessees, of pumps additional to thepumps operated by such district, then the pumping tax or taxeslevied against such tract shall be credited with the amountactually and necessarily spent in such additional pumpingoperations by such owners, his agents, lessees, or sublessees.
(RSMo 1939 ยง 12395)