Instructions: In this task, you're given a passage, further information available on a particular linked term from the statement, and an answer term. Your job is to generate a question that can use the information provided to obtain the given answer. You should use the information on both passage and link information to create the question. Note that the answer to the question should be exactly the given answer, and if the answer is none, the answer to the question shouldn't be obtainable from the passage or linked information.
Input: Passage: It rises in western Wyoming, in northern Sublette County, on the western side of the Continental Divide in the Bridger–Teton National Forest in the Wind River Range. It flows south through Sublette County and western Wyoming in an area known as the Upper Green River Valley, then southwest and is joined by the Big Sandy River in western Sweetwater County. At the town of La Barge, it flows into Fontenelle Reservoir, formed by Fontenelle Dam. Below there, it flows through open sage covered rolling prairie where it is crossed by the Oregon, California and Mormon emigration trails and then further south until it flows past the town of Green River and into the Flaming Gorge Reservoir in Southwestern Wyoming, formed by the Flaming Gorge Dam in northeastern Utah. Prior to the creation of the reservoir, the Blacks Fork joined the Green River south of Green River, today the mouth of Blacks Fork is submerged by the reservoir.
 Link Information: Actual construction at the dam site did not begin until late 1958, when work began on the diversion tunnel that would send the Green River around the dam site in order to clear it.
 Answer: late 1958
Output:
When did construction begin on the dam that formed the  Flaming Gorge Reservoir?