Interstate Highway Construction History.

Additionally, Glenbob mentioned that these ponds were created because the excavation material was needed to build the ramps. But I thought, going through Nebraska, that there were so many big ponds that excavation material must have been needed elsewhere. Then it dawned on me that they also had to raise the roadbed above the adjacent land to prevent flooding. Hence, all these huge ponds were dug out. Also, Nebraska seems to be all sand, at least along I80. This would account for the pristine water we see in these ponds.

Anybody know any facts or trivia related to the interstate highway construction history?

It's primarily a Clean Water Act issue. Road grime, including snow and ice treatments, will flow off the road and into streams, rivers, and lakes. The detention ponds collect the storm water runoff. The soil at the bottom of the detention pond acts as a filter to remove sediment and chemicals from the water before it seeps down into the ground water.

Clean Water Act Regulation of Highway Construction

It's primarily a Clean Water Act issue. Road grime, including snow and ice treatments, will flow off the road and into streams, rivers, and lakes. The detention ponds collect the storm water runoff. The soil at the bottom of the detention pond acts as a filter to remove sediment and chemicals from the water before it seeps down into the ground water.

Clean Water Act Regulation of Highway Construction

So perhaps the water is not as clean as it looks.

I had to go Into the Boss Shop at the Big Springs, Nebraska Flying J this morning for a repair. The shop manager told me that a lot of those ponds resulted from sand being taken for concrete. The roadway is all asphalt now, but maybe it was originally concrete. And there are multiple concrete batch plants along the highway and lots of sand dredging in general.

I find such things interesting too, Bruce. I bought this ebook a few months ago, but haven't read it yet. I wonder if it speaks to your question, and/or you might find it interesting in general?

"The Big Roads: The Untold Story of the Engineers, Visionaries, and Trailblazers Who Created the American Superhighways," by Earl Swift: The Big Roads