The Ditch, the Tunnel, and the Reservoir That Used to Be a Town

Northern Colorado gets about fifteen inches of precipitation a year. Iowa gets more than twice that. Yet this is farm country, and has been since before Colorado was a state, growing crops that have no business existing in a semi-arid basin at five thousand feet.

Every town on this stretch of the Front Range sits where it does because somebody solved that problem. If you want one explanation for how Northern Colorado came to look the way it does, water is it.

The town that was an irrigation experiment

When Nathan Meeker advertised in 1869 for settlers to join a new colony in Colorado Territory, he was selling a specific vision: cooperation, temperance, hard work, and irrigation. The last one was not an afterthought. The whole premise was that a group of people pooling money could build canals that no individual farmer could afford alone.

Members paid a fee and received farmland, access to the irrigation system, and the right to buy a lot in town. The first years were rough. The land was dry and unbroken and the wind was constant. But the ditches worked, and Greeley grew fast enough that other colonies copied the model.

That is the origin of something you can still see from any road in Weld County: a landscape organized around water that arrives on a schedule, in a channel someone dug.

By the 1890s, they had run out

The ditch system worked so well that it created its own problem. By the late 1890s, farmers in northeastern Colorado realized the water rights in the area had been over-appropriated, which is the polite way of saying more water had been promised on paper than the rivers actually carried in a dry year.

There was no more water on this side of the mountains to claim. So the region spent forty years arguing about getting it from the other side.

The tunnel

The Colorado-Big Thompson Project was built between 1938 and 1956, and it remains the largest transmountain water diversion in Colorado. The idea is simple and slightly outrageous: catch snowmelt on the western slope, where the Colorado River begins, and move it under the Continental Divide to the eastern plains.

The centerpiece is the Alva B. Adams Tunnel, thirteen miles long, running entirely beneath Rocky Mountain National Park. It is about ten feet across, concrete lined, and at points it sits 3,800 feet below the surface. It drops 109 feet from the west portal to the east, which is just enough that the water flows through on gravity alone with no pumping.

Construction began in 1940, with crews boring from both sides of the mountain toward each other. They met underneath the divide in June 1944, and the two bores were off by less than the width of a penny.

Water first came through the east portal in 1947. It takes about two hours to make the trip. On the other side it falls nearly 2,900 feet down the Front Range through a series of power plants, generating electricity on the way to the reservoirs.

Horsetooth is not a lake

This is the part people get wrong. Horsetooth, Carter Lake and Boulder Reservoir are not natural features. They are the terminal storage reservoirs for that same project, built to hold the water after it comes down the mountain.

Horsetooth has a specific cost attached. There was a sandstone quarry town in that valley called Stout. The Bureau of Reclamation bought the property in 1946, finished the dams in 1949, and the valley filled with water in January 1951. The town had begun life under a different name entirely, Petra, after the city carved from stone, and was renamed in 1882 when a man named William Stout took over the quarries.

The stone from those quarries is not lost. Sidewalks in Denver, Lincoln and Omaha were laid with it, and buildings at the Chicago World's Fair were built from it. The town itself is under the reservoir. A sign at the southern end reads "Stout, Colo. pop 47 1/2." It is not official, nobody can explain the half, and everyone in Fort Collins uses it anyway.

The one river they left alone

Against all that engineering, the Cache la Poudre is the exception. It is the only river in Colorado with stretches designated Wild and Scenic, and it was the first in the state to receive the designation. On October 30, 1986, about seventy-six miles were protected, thirty of them classified as wild and the rest as recreational.

That designation came out of a genuine fight over whether to dam the canyon, and the outcome was a compromise rather than a victory for either side. Ten years later Congress also designated the corridor a National Heritage Area, specifically because of what happened here in irrigation, engineering and water law.

Which is a fair summary of the region. The Poudre is protected partly because of the history of everything that was done to every other waterway around it.

Why any of this matters now

Water rights in this region are among the most valuable assets anyone can hold, and they trade at prices that startle people from wetter states. When farmland gets developed, the water often matters more than the dirt. When a town approves housing, the binding constraint is usually not land but supply.

You can see the whole system on an afternoon drive. The ditches running alongside county roads. The reservoirs sitting in the foothills at exactly the elevation that makes gravity do the work. The river that got left alone.

None of it is scenery. All of it is infrastructure, and it is the reason there is anything here at all. If you want to go look, the things to do listings will get you started.