Current Edition

current edition

Irrigation

With snowpack in Wyoming continuing to hover between 102 and 139 percent of average, it seems there will be no shortage of irrigation water this growing season.
In the April 4 snow report by the Natural Resources Conservation Service, the Wind River Basin recorded the state’s low snow water equivalent (SWE) of 102 percent of average, while the Upper North Platte and Upper Bear River basins claimed the high at 139 percent.
In the first week of April, 10 Wyoming basins gained average SWE, while one basin stayed the same and only two lost SWE.
“The snowpack is right up around 105 percent of average, and it’s been staying pretty high so far this year,” says Shoshone Irrigation District Manager Bryant Startin of his area in northwest Wyoming that irrigates from Buffalo Bill Reservoir. “The reservoir right now is fairly full, and the Bureau of Reclamation started releasing water on April 1 to make more room for the anticipated inflows to the reservoir this spring.”
The released water has increased flows on the Shoshone River from 350 cubic feet per second (cfs) to 1,000 cfs.
“We’ll start irrigating by mid-April, and most districts are looking to turn on the water on April 18,” says Startin. “The Bureau will increase the river somewhat when we start irrigating, to 1,300 cfs.”
Over the last several years the Shoshone has ran as much as 5,000 to 6,000 cfs under evacuation conditions to make room for spring runoff.
In the March 2011 Wyoming Spring Snowmelt Flood Potential Outlook, issued March 24, many basins in the state are forecast at low to moderate flood potential. The Shoshone River Basin is one that’s forecast to have moderate to high flood potential, with the highest potential across the extreme upper portions of the North Fork of the Shoshone River.
“Current SWE trends are slightly above the 30-year normal, and are below the record SWE years of 1996 and 1997, but are above the SWEs that produced record runoff in 1981 and 1991,” says the report.
Although ice is still thick and there hasn’t been a good measurement since last fall, Wheatland Irrigation District Manager Don Britton says their Reservoir #2 is holding 57,400 acre-feet, Reservoir #1 has 8,340 acre-feet and Reservoir #3 is sitting at 60,000 acre-feet.
“The snowpacks are way up there on the charts, and we’re expecting high inflows and flooding this spring,” says Britton of his area in southeast Wyoming.
Britton says his district has released a little water from their reservoirs, but not to the extent of the Bureau of Reclamation’s releases.
“We had a record year last year – the gauge at Bosler was installed in the 1930s, and last year showed the highest flows measured on it since it was installed,” he states. “Hopefully it doesn’t outdo that this year, but the snowpack is there to do it, and it’s gone up every day.”
Britton says word is that the Snowy Range area is still gaining snowpack.
“The water content in one drainage in the Snowy Range is 37.3 inches of water. There are a few in the 30s, and several in the 20s,” he notes. “Imagine a large area with close to 40 inches of water sitting on top of it.”
Those high water measurements contribute to the forecasted high potential for headwater spring snowmelt flooding across the Upper North Platte River Basin.
“Current SWE trends are near the record SWE years of 1982, 1986 and 1997, and well above the SWE trends of 2009 and 2010,” says the Flood Potential Outlook. The Laramie River Basin also has high potential for spring snowmelt flooding, as does the Little Snake River Basin in southern Wyoming.
The Upper Bear River Basin in western Wyoming has a high potential for flooding, as well, with SWEs above the record SWE years of 1986 and 1995.
Of moisture on the croplands over the winter, Startin says growers in his area have had decent snow cover for some of the winter, as well as spring moisture in the last month.
“The farmers’ biggest challenge now is getting out in the field, because it’s still cold and things haven’t really thawed yet,” he says. “They’re trying to get grain planted now, and get other things ready to go.”
Britton says Wheatland-area farmers have been progressing with fieldwork, with most of the barley planted and oats in progress.
“Everything’s pretty well farmed up that they’ll plant,” he says. “We had two or three really cold snaps with bitter cold, but for the month of March it opened up and was mild.”
The Shoshone Irrigation District recently finished up a large winter project. With funding from the Wyoming Water Development Commission (WWDC), the district was able to line about 600 feet of concrete tunnel, which was over 100 years old, and a 300-foot section of their canal with high-density polyethylene (HDPE) pipe, a hard plastic that’s said to last for years.
“It’s about 70 feet below the invert of the canal to the top of the pipe we had for the tunnel, so we would have had to dig a big hole to replace the concrete,” says Startin.
Britton says projects over last winter with the Wheatland Irrigation District were repairs to flood damage from last year.
Of the 2011 growing season, Startin says, “I think it will be a fairly good year, on the supply side of things.”
“It looks like a year that we’ll have plenty of water again,” says Britton.
Christy Martinez is managing editor of the Wyoming Livestock Roundup and can be reached at This email address is being protected from spambots. You need JavaScript enabled to view it..

Casper – In an update to the Wyoming Water Association Oct. 29, Wyoming Area Manager for the Bureau of Reclamation John Lawson said this last year was a good water year.
    “We did have a good year, which, quite frankly, wasn’t too much above average in some places, but things have been so miserable since 2001 that this last year appeared to be a great year. I’m going to take advantage of giving out good news for once,” he told the audience.
    Pathfinder and Seminoe reservoirs on the North Platte River each hold a little over a million acre-feet (af) when they’re full, Boysen Reservoir on the Wind River holds approximately 740,000 af, and Buffalo Bill Reservoir near Cody holds 646,000 af. “If you total all that up, it’s close to 3.4 million af of storage,” said Lawson. “That represents a lot of storage in Wyoming.”
    Because September is the end of the irrigating season, reservoirs are generally bottomed out by that time. “In September 2007 we had 226,000 af of water in Seminoe, which holds 1.17 million af,” said Lawson. “That was only 22 percent full. In Pathfinder it was the same situation. We had only 17 percent capacity there, with 170,000 af of water. Boysen, again, only had 389,000 af, while Buffalo Bill had 417,000 af.”
    However low 2007 may have ended, in a year’s time Lawson said Seminoe moved from 226,000 af to 534,000 af. “We went from 171,000 in Pathfinder to 348,000. That’s more than double the amount in both of those,” he says.
    Boysen increased from 389,000 af to 628,000 af in 2008. “These are pretty dramatic increases,” said Lawson. “Buffalo Bill is not quite as dramatic, but still good, moving from 417,000 af to 484,000 af this year.”
    More important than the increases from year to year are, Lawson said, the averages. “The 30-year average is how we usually base our progress. Last year Seminoe was at 35 percent of where we should have been Sept. 30. This year it’s at 84 percent. That’s a dramatic increase.”
    “In Pathfinder last year we were also at 35 percent of the average, while this year we’re at 72 percent. That brings it home for us,” he commented. “Boysen has the same kind of results. It was at 64 percent last year, this year it’s at 104 percent of the 30-year average.”
    Buffalo Bill, which he said has always been a little more blessed in water supplies, was at 96 percent last year and this year sits at 111 percent. “That’s the good news aspect in a capsule,” he added.
    However good the news may be, he cautioned that, particularly in Boysen and the reservoirs on the North Platte, we could have one bad year and be right back to talking about the 35 percent numbers again. “It could happen that easily,” he said.
    Lawson said Wyoming’s water managers continue to speak of the need for conservation and allocation and turning off the water as soon as possible. “I didn’t hear the kind of stuff eight or nine years ago, but now I’m having it preached to me, which is good.”
    Regarding water partnerships, Lawson said the Bureau of Reclamation is working closely with the state on endangered species issues. “Part of the funding under some of our programs is to address Endangered Species Act (ESA) funding, and right now for 2009 we received over $11 million for ESA. Half of that went to the Platte River Implementation Program, which is progressing well and moving ahead,” he said.
    “One of the major things we’ve been working with is a partnership with Wyoming on the modification of Pathfinder, which will allow us to restore some space lost to sediment and, more importantly, be able to have the change of use and be able to use the water for environmental purposes for the program, and also to contract with the state of Wyoming so it can be used for agricultural purposes and municipal purposes,” explained Lawson.
    He said the project is going ahead well, with a hearing the week before with the Board of Control. “I testified there for the change of use, and we had opposition but we’ve that resolved with an agreement and I believe we’ll be successful,” he said.
    Wyoming is paying for the modification’s design, a process that Lawson said is over 50 percent complete. “If all the pieces come together, and there are a lot of pieces, we might even see construction a year from now.”
    “All that is good news, and it’s nice to stand here and be able to say that,” he concluded.
    Christy Hemken is assistant editor of the Wyoming Livestock Roundup and can be reached at This email address is being protected from spambots. You need JavaScript enabled to view it..
    According to University of Idaho Extension Water Management Engineer Howard Neibling, managing water levels in the soil on irrigated cropland is all about balance.
    “Capillary and surface tension forces hold the piece of water in the soil pore, and those capillary forces acting in all directions hold that water in place,” explains Neibling. “You also have osmotic or salt-related forces in the soil. Those two forces hold water in the soil, and irrigating crops efficiently is a balance between them.”
    Soil moisture begins with the particle sizes that make up the soil. The three basic soil types are sand, silt and clay. “Sand is defined as 2 mm down to .05 mm, or 50 microns,” says Neibling. “Particles from 50 microns down to 2 microns are silt, and anything below 2 microns is clay. They’re arbitrary lines, but they generally make good sense.”
    “Clay particles look like flagstone, and that shape is what gives them a lot of their properties,” he says. “Two microns is small, and not really visible at all. If you take a meter and whack it into millionths, that’s a micron.”
    If a clay particle is put in a glass of water and allowed to settle, it’ll take four to six hours to reach the bottom, he says.
    “If you have clay particles stacked together you can make a nice brick wall, of sorts, if they’re all oriented in the same direction. Normally they’re randomly scattered and oriented in different directions so you have pore space between them,” he adds, noting that’s where compaction and working wet soil comes into play.
    “Normally, if they’re stacked in all directions and you come across with a piece of equipment and it’s relatively dry there’s enough friction to hold the pieces where they are,” says Neibling. “If they’re wet, the water tends to lubricate those contact points and the particles will slide and consolidate into their most compact form before they hold the equipment up.”
    Neibling refers to an Ohio State University demonstration where a researcher took tractors and ran across a number of plots of wet high clay content soil. “For the next 10 years, whenever it rained he had a lake on those plots. It took 10 years of freezing and thawing to get rid of one compaction,” he says.
    Move the next particle size up to silt, Neibling explains they’re more three-dimensional in shape, similar to a football. “When you stack those you end up with genuine soil pores that are a little more stable, and they’re what holds the water for the crop.”
    In sandy soils, with large pores, he says there are small capillary forces relative to the weight of the water, so there’s rapid drainage and the plant has to exert little pressure to get the water out. “When my family and I first moved to Laramie the sod on our lawn was drying out so fast I got curious,” comments Neibling. He took a sample to the lab and found the sandy soil only held .3 inches of water per foot of sand. “That’s the lowest number I’d ever seen. Sand just doesn’t hold that much.”
    He says soils are made up of those three primary particles – clay, silt and sand – that can’t be broken down, and of soil aggregates, which are clods of all three. “The particles don’t have much in the way of soil pores to hold water, but the clods do, and that’s how you’re pulling and storing the water your crops use between irrigations.”
    “Silt/loam soils can hold 2.5 inches of available water per foot. From .3 in the sand to 2.5 in the silt/loam makes a big different in how we manage that soil,” he says, noting that not all water is truly available for plants to use. “Most plants can use half of the available water, and the silt/loam soils have the most usable water.”
    “On a good hot day, malting barley in the middle of the active growing season will use about a quarter inch of water per day. One inch of available water is gone in four days, and if the root zone is two feet deep you have maximum eight days of water before the crop starts to stress,” says Neibling.
    Neibling says most crops at optimum growth are able to use the top half of available water. Alfalfa at all stages uses 50 to 55 percent and field corn 50 percent. Cereal grains, except through flowering can use over half; from root through flowering they can only use 45 percent. Sugarbeets can use half and dry beans about 40 percent.
    Regarding center pivot systems, Neibling says every time the pivot goes around water is lost to evaporation. “If you’re running a ¼-inch revolution, you’re losing four times the amount of water to evaporation as you would running one one-inch application,” he explains.
    Neibling says growers should pay attention to a crop’s pattern of water use. “While grains are growing you can barely keep up, then all the sudden they shut off, and if you don’t see it and continue to water you get disease problems or you’re pumping water you could use elsewhere,” he explains.
    Also, different crops use water from different areas of the root zone. Sugarbeets use water down to four feet, while alfalfa reaches to six feet or deeper. “Different types of roots utilize different depths,” he says.  
    Surface sealing should also be taken into account when running sprinkler irrigation, especially on high silt soil, he says. “If your drop sizes are too large or the soil surface has been worked a few too many times and the aggregates are broken down, all the sudden you’ve got a lot of runoff.”
    He says that’s where a thin layer of crop residue will help, giving the soil some sort of protection so it doesn’t fall apart and is able to absorb more water.
    “You want to really work toward maintaining a deeper rooting system if you can,” he says of irrigation management.
    Howard Neibling presented information on irrigation to the Wyoming Ag Business Association’s annual meeting in Sheridan in early August. Christy Hemken is assistant editor of the Wyoming Livestock Roundup and can be reached at This email address is being protected from spambots. You need JavaScript enabled to view it..

Worland – “When we think about how we will irrigate our small acreage, it really should be tailored to the specific location and crop and designed in a way that is going to compliment our efforts. We want to maximize yield. We also want to think about the bottom line,” remarked University of Wyoming Extension Educator Caleb Carter at WESTI Ag Days in Worland on Feb. 20.

Efficiency

Efficiency is a common consideration when producers look at irrigation, but Carter suggested looking beyond the field when deciding which type of system is best for a specific location.

“I spent a couple of summers doing research in Powell, and lots of people there have really shallow, 12- or 15-foot-deep wells they use to water their lawns. Those wells are dry until the irrigation water starts running, and then they all fill up,” Carter described as an example of hydrology related to irrigation systems.

He also described examples near Laramie where an endangered Wyoming toad resides, thanks to habitat created by flood irrigation practices.

“When we talk about efficiency, people throw out numbers, but they don’t always account for where that water is going, and it may be going to some other beneficial uses,” he said.

Labor and land

Labor is another important consideration when choosing an irrigation system because there are many different options.

“Do we want a system where we can go to our computer and say, boom, irrigate? Or do we want to go out there and move dams and flood pastures? The technology exists to do either one of those,” remarked Carter.

Various systems also come with different costs and different levels of precision in water application. Finances and production goals are also important considerations when deciding how to irrigate a field.

Topography also impacts which kind of system is best suited to a specific area. For example, flood irrigation or other surface irrigation scenarios require a relatively flat field because water doesn’t flow uphill.

“It’s also important to think about our soil type when we are choosing an irrigation method. If we have a really heavy soil that can hold a lot of water but has a slow infiltration rate, a flood or surface irrigation system is going to be more effective than a sprinkler,” he commented.

Infiltration

In one case, Carter worked with producers who switched from a flood irrigation system to a pivot in their alfalfa field, but yields declined.

“They had really good clay-loam soil. It held a lot of water, and the flood irrigation was able to fill that soil profile. When they switched to the pivot, they weren’t able to apply enough water to fill that root zone,” Carter explained.

Good irrigation requires the soil to both absorb water and disperse it through the soil profile. If soils have a high infiltration rate, water from flood irrigation systems may flow through too quickly, moving below the root zone instead of benefiting the crop.

Water laws

Producers should also be familiar with the water rights associated with their property and usage.

“We sometimes get people buying property that maybe are not familiar with Wyoming water law or their responsibilities, but if we have property and it has water rights, we are responsible for the maintenance of the ditches and the infrastructure that delivers the water to that property,” Carter stated.

This may involve burning ditches, removing weeds or clearing debris to ensure that water flow is not inhibited.

“We are also responsible for head gates and things that impact how water is delivered to our field or property,” he added. “We need to make sure we’re staying up on our responsibilities.”

Different systems

Systems vary from surface irrigation systems, such as furrow, flood or gated pipe, to sprinkler systems, such as hand lines, wheel lines, K-lines and Big Guns. Drip irrigation systems can also be installed, depending on the goals of the producer.

“Hand lines are nice, but they are a lot of labor,” Carter commented. “We can drag K-lines with our four-wheeler or tractor to move them around the field.”

Big Guns are popular with producers who want precision in water application over their pastures, and wheel lines or side rolls may be more appropriate for crops such as alfalfa that shouldn’t be trampled on as they grow.

“Drip irrigation has the potential for the least amount of labor, but it is the most expensive as well,” he continued. “A lot of the cost has to do with how far away the water source is, as well as the shape of the field.”

An oddly shaped field with a lot of topography will present more challenges and costs for even water distribution over the whole crop.

Costs and maintenance

“Costs also have to do with the level of automation. We can have a drip irrigation system where we go out manually and turn the water on in each zone, or we can also have a system where we take our smartphone out of our pocket, say how much we want to irrigate in each zone and turn it on,” he explained.

No matter which type of irrigation is best for a certain field, Carter emphasized using proper management once the system is installed.

“We can have the best, most wonderful system, but if we’re not monitoring, maintaining and operating it in the best manner for that system, it’s not going to do us any good or serve us in the way we designated it,” he said.

Natasha Wheeler is editor of the Wyoming Livestock Roundup and can be contacted at This email address is being protected from spambots. You need JavaScript enabled to view it..

Sheridan – Approximately 100 years ago men dug through a hillside by hand to pipe water for the Meade Creek Ditch Irrigation Drop. A century later, badly eroded soils and pipe decay call for repairs to the project.
    The Meade Creek ditch drop is located outside of Sheridan. The original ditch was hand dug and placed partway in pipe and after decades of use the pipe began to disintegrate. The ditch was one of several stops on the July 18 Wyoming Water Association summer tour held in Sheridan and Johnson counties.
    Vice President of the Meade Creek Irrigation District Jim Roach says four years ago the shareholders on the ditch saw the erosion getting worse and worse and set out to do something about it. To replace the existing system, the irrigation district turned to funding from the Wyoming Water Development Commission, the Sheridan County Conservation District and Natural Resources Conservation Service (NRCS).
    “The ditch covers a lot of country, but it goes through large landowners,” says Roach. “With only 12 or 13 landowners on the ditch, dividing the cost would have been too much.”
    The $500,000 project included construction of approximately 680 feet of new 24-inch irrigation pipe installed by directional drilling, new inlet and outlet structures and irrigation ditch extensions to connect the new structures to existing ditches.
    The purpose of the project was to cut down on erosion and ease some liability. Roach says the liability aspect came in the potential loss of livestock should they fall into the badly eroded area.
    Water was turned into the new pipe in mid-July and Roach says everything looks good so far. The ditch is running 11 cubic-feet-squared (cfs) and will run 15 to 18 cfs at peak season. The ditch does have rights to 20 cfs but Roach says the landowners have put in efficient systems and don’t require that much water.
    Roach says reclamation for the eroded area was taken out of the current project because the cost was too high. He says they plan to revisit the reclamation issue in the next couple of years and their current focus is on fixing the pipe.
    “About two weeks ago a visible section fell off,” says Roach. “The timing of this project was important because there would be more erosion this season.”
    The life of the project is expected to be approximately 50 years.
    Liz LeSatz is the 2008 Summer Intern for the Wyoming Livestock Roundup and can be reached at This email address is being protected from spambots. You need JavaScript enabled to view it..