Nor did the district court abuse its discretion by finding that the untimely disclosure of the eight remaining witnesses also was not harmless. Allowing these witnesses to testify and reopening discovery would have had the same costly and disruptive effects. Nor was it substantially justified merely because the eight witnesses were not employed at Castle Park until after the discovery cutoff date. Sanctioning this argument would force us to read the supplementation requirement out of Rule 26(e). We will not do that.
Sweetwater did not comply with the disclosure requirements of Rule 26(a) and (e). That failure was neither substantially justified nor harmless. The district court did not abuse its discretion when it excluded Sweetwater’s 38 untimely disclosed witnesses from testifying at trial.
C
The next issue concerns whether the district court abused its discretion by declining to consider contemporaneous evidence at trial. On April 26, 2010, the district court set a June 15, 2010, cutoff date for Sweetwater to provide evidence of “continuous repairs and renovations of athletic facilities at Castle Park” for consideration at trial. Improvements made after June 15, 2010, but before the start of trial on September 14, 2010, the district court explained, would not be considered. Sweetwater did not then object to the district court’s decision.
On appeal, however, Sweetwater argues that injunctive relief should be based on contemporaneous evidence, not on evidence of past harm. And if the district court had considered contemporaneous evidence at trial, Sweetwater
