It is declared to be the policy of the Congress that reclamation projects hereafter authorized in the Pacific Northwest to receive financial assistance from the Federal Columbia River power system shall receive such assistance only from the net revenues of that system as provided in this section, and that their construction shall be so scheduled that such assistance, together with similar assistance for previously authorized reclamation projects (including projects not now receiving such assistance for which the Congress may hereafter authorize financial assistance) will not cause increases in the rates and charges of the Bonneville Power Administration. It is further declared to be the policy of the Congress that the total assistance to all irrigation projects, both existing and f