Whoever, being in any manner engaged in the work of dredging or excavating any earth, soil, dirt, mud, sand, silt or other material of any kind from any channelway or harbor within this State, or of removing the same therefrom, in the prosecution of works of improvement or maintenance thereof, wilfully deposits and discharges any of such material outside the territorial limits of this State shall be fined $5 for every cubic yard of earth, soil, dirt, mud, sand, silt or other material of any kind which is so deposited or discharged.