sentences:  Spraying with saturated salt solution (but not dilute solutions) effectively killed the plants; unfortunately this was considered prohibitively expensive, and the engineers selected Harvesta brand herbicide, whose active ingredient was arsenic acid, as the optimal cost-effective tool for eradication.This herbicide was used until 1905, when it was substituted with a different, white arsenic based compound.An engineer charged with the spraying did not think the poison to be a matter of concern, stating that the crew of the spraying boat would routinely catch fish from their working areas and consume them.