Episode 1 - Where does this irrigation water come from?

November 2020

Irrigation is complex–even without delving into water rights, which will be covered in a future "Did you know?" video.  This month, we’re diving into the irrigation water cycle in the Bitterroot, and where irrigation water comes from.

To better explain how irrigation works we reached out to a rancher; who better to talk to about irrigation than someone who’s putting water to a beneficial use in the Valley?  Dan Kerslake, who ranches along Burnt Fork creek east of Stevensville, shared with us about his operation and how he manages water.  “Here on the ranch we’ve got Burnt Fork water,” said Kerslake. “That’s snowmelt, lake fed water that’s regulated as it comes down and diverted through different diversion points or headgates.”

With an average annual rainfall of 13 inches in the Bitterroot, snow is the primary source of water.  As the snow melts it feeds the streams, lakes, and rivers of the valley.

Ranchers like Dan can then access the water through the tributaries feeding water into ditches.  From there, they pump water from the ditches to sprinkler or flood irrigate.

Groundwater can be another source that ranchers utilize to get their land sufficiently watered.  “On this ranch we have a groundwater right, we have two of them actually … We pump directly out of the ground.”

Besides having rights directly off of streams or using groundwater, some ranchers are a part of an Irrigation District or Ditch Company.  Bitter Root Irrigation District (BRID) and Daly Ditches Irrigation District are two of the largest in the area.

BRID manages Lake Como and services 16,665 acres along a 72 mile stretch of their main distribution canal, commonly referred to as The Big Ditch.  Daly Ditches manages 9 main ditches, including the Republican, Ward, and Hedge ditches, totaling 72 miles in length servicing 14,837 acres.  Their water comes from the mainstem of the Bitterroot and its tributaries.

There are many different methods of irrigation.  For farming and ranching in the Bitterroot, two are most common: sprinkler and flood.  “Sprinkler” is used to describe water being spread in a mechanical way via hand line, wheel line, or a pivot system.  Flood irrigating involves using tarps or cinder blocks to flood water across a field.

Historically flood irrigation was the primary method in the Valley, but as sprinkler systems became more advanced they were encouraged as a more efficient method.  Like anything, each system has pros and cons.  As more people switched over to sprinkler systems some areas noticed a significant difference in the water table, areas that had been swampy were drying up and needing to drill deeper for wells.  Flood irrigation may be less efficient, but it helps to recharge the aquifer as it seeps into the ground and eventually feeds creeks and the river.

Dan said the different methods vary from producer to producer and depend on a variety of factors; the location, soil type, and how rocky it is.

If you are curious about irrigation water sources in your area here are a few resources:

First, is the DNRC Water Rights Query System.  The Department of Natural Resources and Conservation (DNRC) is the department of state government with jurisdiction over water rights.  Their online query system allows you to look up surface or ground water rights in a number of ways, easiest of which are by owner or geocode.

Second, is the Water Resources Survey for Ravalli County.  Even though this booklet is from 1958 it still has a lot of valuable information about irrigation water in the valley.  Part 2 of the document has a map that shows irrigated areas and can be used to figure out ditches in your area.

And as always, if you have other questions about water, let us know!