complete a study of the tributary floodflows downstream of Davis Dam;

define the specific boundaries of the Colorado River Floodway so that the Floodway can accommodate either a one-in-one hundred year river flow consisting of controlled releases and tributary inflow, or a flow of forty thousand cubic feet per second (cfs), whichever is greater, from below Davis Dam to the Southerly International Boundary between the United States of America and the Republic of Mexico.

The Secretary shall conduct, at least once every five years, a review of the Colorado River Floodway and make, after notice to and in consultation with appropriate chief executive officers of States, counties, municipalities, water districts, Indian tribes, or equivalent jurisdictions in which the Floodway is located, and others, such minor and technical modifications to the boundaries of the Floodway as are necessary solely to reflect changes that have occurred in the size or location of any portion of the floodplain as a result of natural forces, and as necessary pursuant to subsection (c) of section 1600e of this title.

If, in the case of any minor and technical modification to the boundaries of the Floodway made under the authority of this subsection, an appropriate chief executive officer of a State, county, municipality, water district, Indian tribe, or equivalent jurisdiction, to which notice was given in accordance with this subsection files comments disagreeing with all or part of the modification and the Secretary makes a modification which is in conflict with such comments, the Secretary shall submit to the chief executive officer a written justification for his failure to make modifications consistent with such comments or proposals.