Water Sources for Center Pivot Irrigation Systems
Center Pivot Irrigation Systems require a good water supply both in flow rate and total gallons for a season. If you are considering irrigating 100 acres with an average of seven inches applied during the season, you will need 19,007,800 gallons of water at about 550 gallons per minute. For a one-inch application on those 100 acres, you will use 2,715,400 gallons.
We generally look to either drill a well, or pump surface water from a proximal, lake, river or stream. Since nearly all water demands for irrigation projects are above the 70 GPM regulatory level in Michigan, we must get approval from EGLE for our withdrawals.
At times after exploring these options with various locations and nearby watersheds, it becomes necessary to consider other water supplies. While the limiting factor is nearly always the flow rate, if you are considering a smaller reservoir that is not being continually fed, holding capacity can become an important measurement.
If you have a 300’ x 300’ x 15’ pond on your farm, it will hold 10,098,000 gallons and not likely recharge fast enough during the irrigation season. An option here may be to install a nurse well. If you can get an approval for a 250 GPM well or surface water withdrawal, a nurse well may work. With a week with continuous pumping, you could replace 2,520,000 gallons (nearly replacing the inch pumped).
With a few timely rains from mother nature, you would be in pretty good shape. A larger pond with more capacity would give you some additional buffer, especially when considering surface evaporation and the fact you can never really empty the pond. Expanding your pond to 325’ x 325’ x 20’ would have the capacity to hold 15.8 million gallons. This will give you a buffer when in the heat of the summer with demands of 1.85” / week the draw will be more than 5,000,000 gallons.
Constructing a larger reservoir with the intent of capturing a full irrigation season’s worth of water in another option. We have seen this done when well water had too high a salt content to use or if available surface and well water pumping limitations were exceeded. Pumping restrictions may be favorably impacted with off-season withdrawals that are limited to outside the irrigation season. Another method of bolstering your supply is to route and capture drain tile water into the reservoir. This is generally occurring out of season and often ends up far away in tributaries removing the flow from your watershed. A bonus here is that if any of your tile water has any leached nutrients in it, you can recover them and put them back on your fields.
If you operate a large dairy or are neighborly with one, leachate water can be applied through pivots at a much lower expense that drag-lining or tanker spreading and can be a valuable water source with a minimal amount of nutrient. The greatest value from this application method is that it can be done during the growing season, building yield, limiting soil compaction, and saving expense.
The bottom line here is that you have options even if your preliminary request for a water withdrawal is not approved. Our staff at Michigan Valley Irrigation is well versed at these options and can help you explore alternatives to suit your situation. Give us a call at 989-762-5028, we’d be happy to help.
ABOUT THE AUTHOR
Pete is the marketing manager for Michigan Valley Irrigation, having joined the company in 2016. He was raised on a dairy farm in western New York and graduated from Cornell University with a B.S. in agricultural economics. His entire working career of over 37 years has been involved in agriculture. A farmer helping farmers. When away from Michigan Valley he operates, Joyful Noise Farm, a small livestock and produce farm and spends time with his family.
