“Water was so important they put it in our Constitution, how water is to be divided in Colorado, and it works — still to this day — very well,” Yahn said, explaining that the way it works is the first people who go out and get the water and start using it are the first to have the right to use it.
Water rights are decreed in water court; for the South Platte River the water court is located in Greeley, and once they’re decreed the water rights can’t be changed, even by the legislature.
After ditch companies came and started pulling water off the river and irrigating with it there wasn’t enough water in the summertime in this area, but there was in the wintertime, so farmers grouped together and the legislature passed the Irrigation District Law of 1905.
“They made it so farmers could get into bigger groups and get bonding and things like that, so that they could pay for bigger systems,” Yahn said, explaining that’s what he manages: Prewitt Reservoir, which is 32,164 acre-feet, was built from 1910-1912, has a 30,000 acre service area, and has 250 owners, and North Sterling Reservoir, which is 74,590 acre-feet, was built from 1909-1911, has a 41,000 acre service area and has about 140 owners.
Water rights development in South Platte Basin was influenced by return flows.
“Way back when, you had not only fights within the state between farmers and miners and other farmers, but you also had other states that depended on that river,” Yahn said.
The South Platte compact was negotiated by Delph Carpenter and signed by Colorado and Nebraska in 1923. In a letter from Carpenter to the governor, he said the flow was excessive in May and June and disappeared entirely during the summer; the river frequently became dry for months of each year, to points as far west as the present city of Fort Morgan. He said the flow of return seepage waters coming back to the river from irrigation in Colorado lands had resulted in a constant supply at the interstate line.
“So, he wasn’t too concerned with this agreement that we were making with Nebraska to supply them water, because he said this flow was increasing and he said it soon will be efficient to take care of the full demands of both us and Nebraska,” Yahn said.
Ralph Parshall conducted a study in 1922 on the “Return of Seepage Water to Lower South Platte.” His findings included that return flows were increasing over time and continued to increase mostly due to the general rise of the water table. He said in some areas the water table would rise each year as much as 100 feet and noted the flow increases along the river from 2 to 8 ½ second feet per mile. He also said diversions from the river after spring floods had subsided were practically all from seepage water.
“So, he’s saying after the snowmelt heads out, there’s really no source of water except for these return flows that come back to the river,” Yahn said.
From 1930s to the 1970s, America got rural electrification and people realized there was groundwater under the ground, so they began drilling wells. In the 1950s and 1960s there were droughts, so farmers were looking for other sources of water and really went after wells along the South Platte River.
In 1956, Parshall told the Rotary Club there were several issues impacting the dwindling river. While past records had indicated a steady increase in return flow to the river, in 1956 it was found that the seepage return was practically nothing and Parshall said that was partly due to the fact that between Kersey and Julesburg more than 4,000 irrigation wells pumped to deliver enough water to fill Horsetooth Reservoir four times during the 1955 season, twice as much water as it would take to fill all the reservoirs in this area — North Sterling, Prewitt, Jackson, Empire, Riverside and Julesburg.
Parshall also said it appeared obvious that we couldn’t continue depleting the groundwater at that rate. From 1954 to 1956, North Sterling Reservoir either never filled or was just a little over half full. Records show a similar pattern in the 1960s.
“You can probably feel the tension already; you have these guys with reservoir water with a 1910 water right and you have wells that were drilled in 1950, pumping away and growing crops while these guys sit here with nothing, fields blowing…” Yahn said.
He spoke about how the river is administrated, using an example with the Springdale Ditch (1886 water right), Sterling No. 1 Ditch (1873 water right) and Harmony No. 1 Ditch (1895 water right).
“What happens is you have these ditches that seep and all this water … seepage from the ditch, people call it wastewater, it actually goes back to the river and somebody else down river uses it,” Yahn said. “So, the interesting thing is even though Springdale has an 1886 water right, if Sterling No. 1 doesn’t have all their water, they call up the river commission and say ‘hey, we don’t have our water, you need to bring it us.’ The river commissioner will call up Springdale and say ‘you need to shut off; Sterling No. 1 doesn’t have enough water.’ It’s a pecking order,” Yahn said.
In the 1950s, wells were put in and intercepted water that was going back to the river. All the sudden it became evident in the reservoir system that they didn’t get any water. So, Colorado made a way that you can replenish this well pumping if you put in some recharge ponds.
“It’s a good way to allow people to pump their well, but still not injure senior water rights,” Yahn said.
In 2002, which was a dry year, not all the wells were replacing very much and the return flows back to the river per mile from Kersey to Julesburg was around four CFS for every mile. In 2012, after wells were required to replace their water, the line jumped back to what Parshall said, showing that the return flows were finally back to what they used to be.
Water is going to become an even more precious resource in the coming years, as the population in the South Platte Basin is expected to increase from 2.5 million to 6 million by 2050, and new water demand will increase from 359,000 to 525,000 acre-feet.
“We have to deal with that with water and what we’re trying to work towards is ideas that keep people farming, because if you’ve ever gone down into the Arkansas Valley, in Rocky Ford or anywhere in southeast Colorado, where Aurora went down applied for the water, took it out, it just devastates the community. So, we’re trying to come up with alternative ways to keep farmers farming, try and get water for municipalities and work together so that we can do that,” Yahn said.
There are projects that are being worked, but even if all the projects are built there will still be a shortage of 99,000 acre-feet, which is about 1.5 North Sterling Reservoirs, and if just 62 percent of the projects are completed there will be a shortage of 362,500 acre-feet, which is about five North Sterling Reservoirs.