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 future, in the Pacific Northwest shall not average more than $30,000,000 annually in any period of twenty consecutive years. Any analyses and studies authorized by the Congress for reclamation projects in the Pacific Northwest shall be prepared in accordance with the provisions of sections 835j to 835m of this title. As used in sections 835j to 835m of this title, the term “net revenues” means revenues as determined from time to time which are not required for the repayment of (1) all costs allocated to power at projects in the Pacific Northwest then existing or authorized, including the cost of acquiring power by purchase or exchange, and (2) presently authorized assistance from power to irrigation at projects in the Pacific Northwest existing and authorized prior to .September 7, 19661966-09-07