The U.S. Government Accountability Office stops short of suggesting the fire could have been put out sooner.
However, it says there are conflicting accounts of why a special gel-dropping air tanker was not used in the early hours of the blaze.
The Forest Service is also being asked to come up with a policy for using firefighting aircraft at night.
The Station Fire, the largest wildfire in Los Angeles County history, started in the Angeles National Forest in August of 2009.
Two firefighters died, 89 homes were destroyed and $160,000 acres burned.
The report urged the agency to "clarify ambiguous operational processes" to improve how it manages future fires.
The Associated Press contributed to this report.