A poorly drained area of an upper pen where mud has built up in a high traffic area.
The inquiry team's report to the Utah state director noted that the centre is located on a steep hillside on the east slope of the Oquirrh Mountains and therefore receives a high amount of runoff.
The water ultimately ends up in the horse pens, contributing to the muddy conditions.
The review team recommended that an agricultural engineer familiar with large animal holding facilities be hired to evaluate the soil conditions, site, pen layout, and construction and maintenance procedures to see if there is a long-term solution to the issues with poor drainage and mud.
The review team suggested that some of the horses be moved to ease the problem, and the bureau indicated it would shift about 200 horses from Butterfield to its facility in Gunnison.
The reduced numbers would allow staff to improve corral conditions for the remaining horses.
Horses will be transported in a large single-deck semi trailer beginning on Monday.
The team made other recommendations for medium and longer-term management of the centre, which the bureau said it would consider over the next few months, pending the results of the agricultural engineering studies.
The review noted that the centre had always struggled with controlling drainage and a lot of mud during the spring.
"This spring has been exceptionally wet in the Salt Lake Valley where the facility is located.
"Despite the best intentions and efforts of the employees at the centre, it is the opinion of this review team that the weather conditions this spring and poor drainage have created this situation where many animals do not have access to sufficient areas to lie down in many of the pens ... in the recent past and at the present time.
It noted that the centre was originally designed for summer and autumn use.
Since becoming a year-round facility, the bureau had struggled with drainage and mud problems, the team said.
"At this time the situation has reached the point where it cannot be addressed without major changes in maintenance and the physical layout of the centre."
It recommended that the facility be kept at a reduced capacity during the winter and early spring months until issues associated with poor drainage and excessive mud in the pens can be resolved.