Greeley needed to have water to grow crops.
Irrigation was important for Greeley to grow because natural precipitation was scarce.The plan was for 4 ditches or canals to be dug in Greeley. Only three were built. Oxen were used to plow the canals.

Nathan Meeker got the idea for using irrigation ditches from a trip he took to Utah. He saw communities using ditches for their crops and thought they would work for the new colony.

Robert Cameron and H.T. West were given the job to plan the town and the No. 3 ditch.
Greeley didn't know a lot about irrigation to start. They made many mistakes with the No. 3 ditch. They had to study other ditches before No. 3 was able to get enough water to the crops. The ditches were difficult to dig because the sides would errode (wear down) and water would leak in.

The ditch was dug using horses, oxen, mules and a tool like a plow.
The ditch is 13 miles long. One of the problems was that Greeley did not have enough workers. So earlier residents were used to help. Any able bodied man who lived in the colony became one of the "volunteers". The men used pick axes, shovels and the plow to make the ditch.

The ditch was begun in May of 1870 and finished June 10, 1870.
The ditch followed the bluffs in the town so instead of being straight, it zig-zagged. The zig zags made the ditch water flow slower. Residents also still had to face little or no water at the end of the growing season because the ditch would be low on water. Not until reservoirs were built was the ditch able to water crops for the whole growing season.

The ditch begins at the Cache La Poudre River. It empties into the Platte River.
The ditch crosses Greeley from west to east. At first, it irrigated over 5000 acres of land. Today it irrigates about 1500 acres of land.

The ditch is important for two reasons: it was the first decreed ditch in the USA, and the water law "First in time has the first rights" came from it.
The law means the first people to use the water has first rights even over people who may live closer to the water. Nathan Meeker and Robert Cameron met to discuss the water rights in 1874. Meeker was there for Greeley and Cameron was there for Ft. Collins. They met at a school house in what is now Windsor. The meeting was the start of today's water laws.

On May 16, 2009, the No. 3 Ditch New Computerized Headgate was dedicated.
The new headgate is using a computer to know when to release water and how much water to release. The computer checks the level of water in the ditch and opens or closes the gate to keep the water at the correct level.