This is from the AZG&F website...
http://www.azgfd.gov/artman/publish/article_383.shtml
Portion of Big Boquillas Ranch closed to vehicle access this hunt season
Public Advisories
Sep 13, 2005
Closure area is smaller than last year;
Use of ATVs, horses not allowed anywhere on ranch
The Arizona Game and Fish Department is advising hunters that a portion of the Big Boquillas Ranch in northwestern Arizona is closed to vehicles this hunting season. Foot access will be allowed in the closed area. The closure affects approximately 60 square miles around the Rose Well Camp area and is much smaller than the 175 square miles closed in that area in 2004.
The remainder of the ranch's established roads are open to vehicular access by hunters, although the use of all-terrain vehicles (ATVs - quads and motorcycles) and the transportation and use of horses and livestock on the ranch are prohibited.
There are three primary reasons for the restrictions on hunting by horseback:
(1) The Navajo Nation Division of Natural Resources is concerned with the potential introduction of any foreign animal disease, such as vesicular stomatitus, or noxious weeds that could be introduced from animal feed brought onto the ranch, such as Russian knapweed.
(2) The division is not able to monitor and check certificates or feed, if horses were allowed for outdoor recreation, including hunting. The division does not have the staffing, funding or agreements in place to manage this activity.
(3) The division is concerned about liability issues in the event damages are realized when animals are infected or range land impacted by noxious weeds. There could potentially be a significant financial impact to the lessee.
The Big Boquillas Ranch is approximately 730,000 acres and comprises nearly one half of Game Management Unit 10, which is located near Seligman. More than one half of the ranch is private property owned by the Navajo Nation and the remaining portions are state trust land leased by the Navajo Nation. For questions about the restrictions, contact the Navajo Nation Division of Natural Resources at (928) 871-7068.
The Arizona Game and Fish Department asks that hunters obey all signs and instructions while this closure is in effect, and respect all ranch land by avoiding the following: cross-country vehicle travel, littering, leaving gates open, and camping too close to waters.
To view a map of the closure area, click here.