When Senator Goldwater introduced his GCNP enlargement bill in 1973, he set the upstreammost boundary point at the Navajo Bridge. On the screen shot (courtesy of Google maps) below,
that is the yellow line of US 89 crossing the Canyon (bottom of picture). Park advocates believed that the best way to unify administration of river traffic would be to include in the Park, Lee's Ferry with its boat loading and launching facilities . (The photo labels that as "Marble Canyon", which it is not.) However, the Lee's area is also used by upstream traffic into the Glen Canyon NRA, and the Park Service preferred to keep the overall jurisdiction with the NRA, while stationing there the rangers dealing with downstream river trips. Moreover, geologically, it made more sense to exclude rocks above the Kaibab limestone. The result was to use the Paria's entrance into the Colorado as the most suitable starting point, as shown on this shot (sorry about the shadow). The thin brown/tan Paria running southwest alongside the road here is quiet;
it would be exciting to have the photo showing a big, muddy flood. The point, however, would be the same: Where is the "line" of the boundary? The Paria delta, and even its midpoint, have width, which would show up differently in different flows. And how does the line go across the Colorado? Perpendicular to a midpoint (itself not exact and stable), or following the Paria flow line? Should the line go far enough upstream to include any of the Paria at its flood maximum? And how is the line affected as the Colorado fluctuates, much less floods?
All this dancing on pins is just to illustrate in a small, (probably) inconsequential way that a boundary described by map or words can be satisfactory even when not an exact legal line, IF the parties are looking to cooperate on what is a practical, sensible, usefully informative and educational division. Looking at this photo, it seems easy enough to place a line, and also easy enough, given the questions I posed, to see how squabbles could arise when two parties with contrary interests feel justified in placing different lines. Here, that is unlikely to happen. By conceding Lee's Ferry to the NRA, while allowing GCNP duties to be carried out on NRA turf, conflict was avoided. More important, a boat trip, passing by the Paria, can understand and appreciate a geological beginning of what is happening as the Grand Canyon walls rise: Now we enter the Canyon; now we are in the Park. Not all the ambiguities of The Line will be so easily and satisfactorily mastered.
And right here at the beginning is the place to re-state, in an insistent way, that the river, starting from that Paria "line" and going down to the Grand Wash Cliffs, the entire water surface from left side to right side, was included within the Grand Canyon National Park by the 1975 Act.
A bit of remembered history. In 1972, the fight over control of river traffic boiled up and over. Senator Goldwater got personally involved, concerned about the impact of the increasing numbers of visitors and the use of motorized rafts to push large numbers of people down the river in a short time. At that time, the river was under, arguably, seven jurisdictions. NPS at the Park was certainly the dominant; no one else wanted to get involved. Goldwater held a meeting at his house with an agenda to discuss river matters and to launch what he hoped would be a cooperative effort to enlarge the National Park. I remember as part of the river discussion that he wanted Park legislation to result in a single river administration.
When the legislation Goldwater introduced passed the Senate, it contained this language on the map (113 20,000 J / Dec 73): "Colorado Riverbed, Proposed boundary on the south bank of the river; NOTE: Subject to concurrence of the Hualapai Nation". In its consideration of the bill, the House determined that this language was inappropriate; the riverbed was not the issue, and the Hualapai Nation did not extend beyond the south bank and into the river. The language on the map was changed to read: "Boundary on South Bank of Colorado River (River Mile 164.8 to 273.1)".
A year later, when the legislation was the subject of a conference between House and Senate to settle disagreements, the report of 17 Dec 1974 referred to the final map (113-20, 021 B and dated December 1974); it accepted the House determination. The conference report also contained language about Wilderness in the expanded Park, which was to be the subject of a new study to include "all lands--including the entire river from the mouth of the Paria to the headwaters of Lake Mead--within the revised park boundaries".
From beginning to end, the legislative history of P. L. 93-620 accepts, does not show contests over, the establishment of a unified administration of the river under GCNP. There will be much more about this in the segments adjacent to Navajo and Hualapai lands.