I saw this thread and had to respond. This kind of talk is my job, after all.
But, because it is my job, this post has a lot of info. Sorry to ramble.
The Colorado River Water Conservation District and the Colorado Division of Water Resources have a great map that outlines all 15 major west-to-east slope diversions in Colorado. Almost all of the west-to-east diversions mentioned by cstork are on this map. The map correctly identifies which project each diversion tunnel belongs to and the average amount of acre feet, not cfs, the tunnels divert, annually. For instance, through Moffat Tunnel, Denver Water diverts around 53,000 af a year.
As for the Bureau of Reclamation, we have numerous projects in Colorado--and that's just us. There are many other projects from various water districts, municipalities, and so on. But, to see Reclamation's Colorado water projects, visit: www.usbr.gov/dataweb/html/colorado.html
Reclamation's work in Colorado is split into two Regions--the Upper Colorado Region (west slope) and the Great Plains Region (east slope). My area office and my work are under the Great Plains Region.
Our Area Office here in Loveland oversees two major water diversion projects: the Fryingpan-Arkansas Project which brings water from the Fryingpan River to the Arkansas River basin; and the Colorado-Big Thompson Project, which brings water from the head waters of the Colorado River to the Big Thompson and Poudre River basins (really, the South Platte River basin).
On average, we divert around 40,000 af a year through the Fry-Ark project (but our water right allows us to divert up to 69,000 af). Fry-Ark water taken from the upper Fryingpan River is diverted through the Boustead Tunnel. The old Hagerman railway tunnel is used for diversions, too (I think it is called the Carleton Tunnel?), but they are not large and the tunnel is not maintained. I am not sure what project uses that tunnel, but it isn't us.
Via Boustead, the Fry-Ark diverts water to Turquoise Reservoir. We own Turquoise, but because Turquoise was originally built by Aurora and Colorado Springs for the Homestake Project, we have what is called "Conveyance" contracts with them. They still store Homestake Project water in Turquoise.
Twin Lakes is a natural lake, but Reclamation enlarged it in the late 1970s. We run water from Turquoise, through the Mt. Elbert Power Plant and into Twin Lakes. From there, water flows on down to Pueblo Reservoir.
Similarly, for northeastern Colorado, the Colorado-Big Thompson Project diverts upper Colorado River water through the Alva B. Adams Tunnel. We divert around 240,000 af of water a year, even though our C-BT water right is for up to 310,000 af a year. Three reservoirs, Willow Creek, Granby and Shadow Mountain, collect snow melt runoff to the Colorado River headwaters. We pump it up, through Grand Lake, and into the tunnel. This water eventually winds up in Horsetooth and Carter reservoirs.
Both of these projects were built in cooperation with the west slope. To "compensate" for the water diverted, one reservoir per project was constructed to help offset the diversion impacts to the west slope. For the Fry-Ark, we built Ruedi Reservoir. For the C-BT, we built Green Mountain Reservoir.
You can learn more than you ever wanted to know about these two federal water diversion and storage projects and the Bureau of Reclamation by visiting http://www.usbr.gov/
or just give me a call or send e-mail if you have other questions.
Other agencies who can answer questions about this complicated water system include the Colorado River Water Conservation District (Glenwood Springs), the Southeastern Colorado Water Conservancy District (Pueblo), the Northern Colorado Water Conservancy District (Berthoud), and, of course, the Colorado State Engineers Office. There is a division engineer in each of Colorado's seven major river basins. And, all these organizations are easy to find on the web.
I'll wrap this up now because I'm feeling an urge to editorialize on the various roles of agriculture, M&I (municipal and industrial), and fish and wildlife in Colorado's water history.