Outfall culvert at the Kaw River
Public Domain: Published Prior to 1923
View this photo at books.google.com
BH Photo #451948
The tunnel is normally flooded, and wide enough to turn a 20 foot boat around in. Height is at least 15 feet.
This large tunnel was constructed under a limestone ridge in Kansas City, Kansas for the purpose of diverting Turkey Creek into the Kansas River. Turkey Creek, which is a prominent stream in northeastern Johnson Co. and southeastern Wyandotte Co. Kansas, originally continued to the northeast often flooding the West Bottoms of Kansas City, Kansas and Kansas City, Missouri.
On 12, April 2009, KMBC Channel 9 out of Kansas City, MO showed some footage of the tunnel in a special weather segment. Although I do not know the dimensions of the tunnel, it appears large enough that at vehicle could easily be driven through it, although this is undoubtedly forbidden, not to mention dangerous.
I have added some new information for this tunnel. Sources
http://www.rosedale.org/turkeycreekcelebration.htm
http://www.kmbc.com/r/15980447/detail.html