Didn't see anything about road closures on I-29. But there are some "Lane" closures on I-29 from Sioux Falls to the Madison Exit. and other construction issues.
http://www.sddot.com/sfprojects/other.aspLook at #4 and #7 at the above address for the I-29 info.
But they don't say anything about a complete closing of I-29
OOoo just found this one
http://www.safetravelusa.com/sd/It's a good one too. A map showing the construction and traffic affects.