Can I receive credit for past environmental stewardship activities/projects?
In order to be recognized, a stewardship activity (or its benefit) must be ongoing or have occurred within a year. Recognition can be given for a one-time change that yields on-going benefits as long as the change is not reversed and thus the benefit erased. A formulation change 6 years ago that eliminated all hazardous components from a product can be recognized as still yielding benefit, provided the same product is still being made and would still be allowed to change back (the hazards haven't since been outlawed). Similar ongoing benefits may come from water conserving changes.
In three categories that relate to energy there is a five-year limit on recognition of ongoing benefit (questions #12 Green Building Implementation, #18 Process Energy, and #19 Transportation Energy). The five-year energy limit adjusts for the fact that costs associated with energy will always drive decisions in favor of greater efficiency. Without this time limit almost everyone could point to past improvement. If everyone got this credit it would become meaningless.