Outdoor Services Crew

Tuesday, May 24, 2011

Turning on some Ditches

In the past I have spoke about the water rights that are owned by CU-Boulder and are extensevly used to irrigate campus property. Last year there was some discussion about bringing a historic section of ditch back into an operational status. Last summer I started to investigate what it might take to allow water to once again flow in the Norlin Quad. There were some sections that had collapsed under sidewalks and some portions that were clogged with roots and debris. This winter we were able to make repairs to these sections, and a couple of weeks ago we brought water down these sections for the first time in decades.

In the video above you can see we created a small diverter in the ditch lateral. This board is used to help create "Head Pressure" behind the board. Basically allowing the water to gain elevation and provide the ability to divert the water into a section of ditch that is at a different elevation. This trick is not new and was used by early settlers to get water into locations. The most common method for moving water to a different elevation by gravity only is the use of holding ponds. This allows you to move water to one location and use a pond as a method to "raise" the water elevation and send it out through another ditch at a higher elevation.

This section of ditch in the Norlin Quad used to be used to flood irrigate the quad. If you were to look closely at the grade it slopes from south to north in the quad. At the south and north sides of the quad there are two open ditches. If you were to look closely at the video above you notice a slit in the stone, these slits are about every 5-10 feet along the entire ditch. Just like we put a piece of plywood in the slit to help divert the water into another lateral the night watermen used to put boards into these slits and let the ditch overflow. Then gravity would take over and allow water to flow across the quad. The ditch on the north side is used for conveyance but also to collect excess water that flows across the quad, then that water can be used further downstream to irrigate other sections.

It was really a great feeling when we started to flow water down this ditch just prior to graduation. For many decades this was just an open ditch with nothing in it but concrete and now on nice sunny days you can hear trickling water in the Norlin Quad once again.
It is amazing looking back at the ingenuity of people, today nobody would ever think of a gravity only delivery system. This is one system that if you keep it clean, water will always flow. There are no concerns about pumps going down, electricity going out or any kind of mechanical failure. Mother Nature can move water very easily, we just have to want to allow her to do it and have patience and she will get it done.