The Secretary may hereafter partner, provide a grant to, or enter into a cooperative agreement with local joint powers authorities formed pursuant to State law by irrigation districts and other local water districts and local governments, to advance planning and feasibility studies authorized by Congress for water storage project: Provided, That the Secretary shall ensure that all documents associated with the preparation of planning and feasibility studies and applicable environmental reviews under the National Environmental Policy Act [42 U.S.C. 4321 et seq.] for a project covered by this section shall be made available to any joint powers authority with whom the Secretary enters into an agreement to advance such project: Provided further, That the Secretary, acting through the Commissioner of the Bureau of Reclamation, shall ensure that all applicable environmental reviews under the National Environmental Policy Act, to the degree such reviews are required, are completed on an expeditious basis and that the shortest existing applicable process under the National Environmental Policy Act shall be utilized, including in the completion of feasibility studies, Draft Environmental Impact Statements (DEIS) and Final Environmental Impact Statements (FEIS): Provided further, That the Bureau of Reclamation need not complete the applicable feasibility study, DEIS or FEIS if the Commissioner determines, and the Secretary concurs, that the project can be expedited by a joint powers authority as a non-Federal project or if the project fails to meet applicable Federal cost-benefit requirements or standards: Provided further, That the Secretary shall not provide financial assistance towards these studies or projects, unless there is a demonstrable Federal interest.