“ The non-Federal share of the United States contribution to the costs of such projects may not be derived from Federal grant programs. In the case of a project carried out in Canada or Mexico, the non-Federal share of the costs of the project may include cash contributions from non-United States sources that are used to pay costs of the project. In the case of a project carried out in Canada, funds from Canadian sources may comprise up to 50 percent of the non-Federal share of the costs of the project.’’. ”