Protecting and enhancing water quality on the Colorado
Mesa County and its Grand Valley are the agricultural mecca of the Colorado River Basin in Colorado. Fruit dominates the economy here—and it shows. Endless rows of peach trees, apple trees and grapevines line the highways and back roads. Packing sheds with rusted metal roofs dot the fields, and tall steel towers topped with giant fans stand sentry over the orchards and vineyards, prepared to pull warm air down from the sky to the ground to battle late spring freezes and early fall snow.
In the midst of all this sweet growth, Mel Rettig’s road-side vegetable farm stands out, plain and sturdy, offering corn, tomatoes, green peppers and pinto beans. A faded red and white wooden sign on Highway 141 directs customers back to the vegetable stands behind his home, which sits in the middle of a flat 60-acre spread his father began acquiring in the 1930s. Rettig is at home today, a rarity in the winter. Typically, he and some of his neighbors are on the road, travelling to water meetings in Denver, Glenwood Springs and other points in between—or beyond. He is one of a small posse of de facto, volunteer and self-taught water experts who have worked for decades to understand and master the chemistry of the Colorado River. If you’re a fruit or vegetable grower in the Grand Valley, you’re a water expert or you’re out of business. It’s that simple.
On Rettig’s dining room table, pages of soil reports from Colorado State University labs give him the most recent take on the chemistry of his soil, its nutrient levels and equally important, its salt content. Salt and other dissolved solids have naturally flowed in Colorado River water for centuries, largely because local Mancos shale formations and hot mineral springs introduce them to the river. But as water utilities and irrigators have taken larger amounts of its flows, the river has effectively lost its ability to dilute itself. And return flows from irrigation carry more of these impurities, plus nitrates from fertilizers, back into the river and its streams. The river’s water quality deteriorates as it moves downstream, with California’s irrigators feeling the biggest impacts.
Rettig, like dozens of other farmers in the region, has participated in the Federal Salinity Control Program for nearly 30 years to take advantage of new irrigation techniques and water delivery systems that keep salt out of the river. He and other growers, thanks to years of research and modernization, have learned how to use special pipes and sprinklers to keep irrigation water to a minimum and, as a result, reduce the amount of salt in return flows that make their way back to the river.
In the Grand Valley, the Salinity Control Program has been so successful that most new, federal investment is scheduled to wind down in two years. Salt levels in the river here and farther downstream in Arizona and California are down by roughly 1 million tons per year, according to Jim Currier, basin states salinity program manager for the Colorado State Conservation Board. “They have documented substantial decreases,” he says.
But living with the Colorado River, maintaining the delicate balance between the soil, the groundwater and the river, requires constant vigilance. Changes upstream—such as new diversions by the Front Range or by rapidly growing towns in the basin itself—could alter the river’s chemistry and throw these farms back 30 years.
“There is an unfair notion out there that the Colorado River is unsuitable for human consumption. Is there more [salinity] than in a high mountain stream? Yes. Is it unsuitable for humans to drink? No.” – Dale Tooker
“When I grew up, we had a big white spot out front because it was so salty,” says Rettig. It took years to return the soil to health, but that same field is now one of Rettig’s most productive vegetable plots. The key is careful management of water—in the river and on the soil. “Anywhere you irrigate, you can manage salinity on the farm,” Rettig says. “There is a fine point in managing it.” Apply too little water, and salty groundwater can rise to the soil’s surface and damage already-stressed fruit and vegetable crops. But, “If you put on too much water, it picks up the salt, and the water carries the salt out to the river,” says Rettig. And it becomes the next downstream user’s problem.
High salinity levels aren’t just hard on fruits, vegetables and other agricultural products. Salt is corrosive and can damage water treatment systems or destroy household pipes and faucets. Domestic water providers in the Grand Valley, such as the Clifton Water District, know the struggle well. The Clifton Water District diverts directly from the river, where salinity levels can exceed 500 milligrams per liter, the upper limit of what’s considered acceptable for municipal use. In 1997, Clifton built an innovative—and expensive—plant to remove salt and other dissolved impurities from its water using membrane-filtering technologies known as reverse osmosis and nano filtration. It costs about 15 cents more per thousand gallons to treat water this way compared to more traditional methods.
Dale Tooker, manager of the Clifton Water District, doesn’t want to give the Colorado River a bad rap, though. He says his district treats its water carefully in part to meet stringent regulations and to improve aesthetics, such as taste, odor and hardness. “There is an unfair notion out there that the Colorado River is unsuitable for human consumption,” Tooker says. “Is there more [salinity] than in a high mountain stream? Yes. Is it unsuitable for humans to drink? No.”
It’s not just salt that haunts the river. Selenium, which is even more difficult to treat, may be the most worrisome, recent issue on the Colorado. “They sell selenium in the health food stores as a beneficial thing, but in high doses it’s toxic to aquatic life,” says Steve Gunderson, director of the Colorado Department of Public Health and Environment’s Water Quality Control Division.
Although geography helps determine the chemical makeup of water, what humans do often exacerbates the problems. “Selenium is naturally occurring,” Gunderson says, “but it’s mobilized by human activity.” The Grand Valley, for example, has prevalent Mancos shale deposits that are laden with selenium. Irrigation water percolates through the shale formation, gathering selenium and delivering minute yet harmful doses of the trace metal to the stream. To combat these types of issues, Gunderson and others have encouraged farmers to use sprinklers instead of flood irrigation and to replace earthen water delivery systems with pipes to reduce the amount of water seeping back into the soil, the groundwater, and ultimately, the river.
“If it’s not handled properly, these types of developments will be the main source of selenium contamination in the future.” – Sonja Chavez de Baca
Sonja Chavez de Baca, coordinator of the Gunnison Basin/Grand Valley Selenium Task Force, says the Colorado mainstem, thanks to improvements in irrigation, has seen selenium levels drop by about 40 percent at the state line—to 4.6 parts per billion down from 7.8 ppb—since 1986, according to a USGS study undergoing review. But more work remains. To maintain compliance with Colorado Department of Public Health and Environment standards to protect aquatic life, the river needs to register at 4.6 parts per billion for the entire length of the mainstem. While the Colorado River currently meets that standard upstream of the Grand Valley, it picks up significant amounts of selenium as it travels through the agricultural region, and gets another dose from the incoming Gunnison River. The Gunnison, a major tributary to the Colorado, is the source of approximately 52 percent of the selenium load at the state line while the remaining load is attributed to the Grand Valley. Too much selenium causes curvature of the spine in young fish, making them poor swimmers and more susceptible to predators, and can also harm aquatic birds.
More work with irrigators in the Gunnison Basin, and equally important, with new development there and in the Grand Valley, will be key to achieving permanent reductions in selenium on the mainstem, Chavez de Baca says. “It’s not just about agriculture anymore. We’re focusing more on urban development in areas in the Grand Valley because it will occur on previously undisturbed or unirrigated adobe soil, which are, on average, 34 times higher in soluble selenium. If it’s not handled properly, these types of developments will be the main source of selenium contamination in the future.”
Chavez de Baca says the task force will have a draft selenium management plan out this summer and that the group hopes to make use of existing federal and state funds to continue bringing selenium concentrations down through water efficiency improvements and public outreach.
Still another water quality concern on the river is the temperature of its flows. Gunderson, who lives and breathes water quality statistics, monitors stream temperatures closely because of their direct impact on aquatic life and the endangered fish the state is legally obligated to protect. Rising temperatures caused by diminished streamflows are regulated like a pollutant in Colorado.
Levels of salinity and selenium and water temperatures could all increase if new water diversions occur. Existing diversions have already dangerously lowered streamflows, causing ecologic problems in the headwaters in Summit and Grand counties and exacerbating problems with water quality farther downstream.
To compensate for these diversions, West Slope water managers have worked hard to ensure that replacement water supplies from West Slope reservoirs such as Wolford Mountain, Williams Fork and Green Mountain is released at times and in adequate quantities to dilute water that would otherwise be excessively high in salt and selenium and harmfully warm for fish and other aquatic life. Although water from these reservoirs is of lower quality compared to headwaters flows being diverted out of the basin, improved technology has allowed water managers like the Colorado River District to optimize releases to minimize water quality impacts. For example, a multi-level outlet was designed and constructed at Wolford Mountain Reservoir to enable operators to draw colder and denser water from the bottom of the reservoir to cool the river. Operators can also manipulate the reservoir’s outlet control to release lighter, less saline waters to benefit the river system.
On the Fraser River in Grand County, water quality concerns center on sediment, the loading of nitrates and phosphorous, and water temperature. To combat these problems, Grand County water and sanitation districts have hired engineers to work with developers to keep soil from migrating off newly developed properties, altering stream beds and harming aquatic habitat. And the Colorado Department of Transportation, Grand County and Denver Water are teaming with local agencies on a $300,000 project to transform a Denver Water collection pond at the base of Berthoud Pass into a settling facility to help remove thousands of pounds of road traction sand from the river.
“Having more water would be the ideal way to deal with some of this, but we’re dealing with a de-watered river.” – Kirk Klancke
New wastewater treatment plants are able to remove roughly 98 percent of the nitrates in the water, says Kirk Klancke, manager of the Winter Park Ranch Water and Sanitation District, and in the next decade new nutrient standards from the Colorado Water Quality Control Commission will require the treatment plants to remove much of the phosphorous—which stimulates the growth of stream-choking algae—as well.
Aging treatment plants and water delivery systems are a concern statewide. Gunderson says several Colorado communities have been able to upgrade their water systems thanks to federal stimulus funds. But more money will be needed. West slope communities may get additional funds from large utilities such as Denver Water and the Northern Colorado Water Conservancy District, which have pledged financial help in exchange for local blessing over new diversion projects.
But the list of water quality issues doesn’t end there. In Garfield County, concern about potential groundwater contamination related to natural gas drilling has grown since 2004 when a resident of Silt discovered benzene, a known carcinogen found in natural gas, in West Divide Creek. Stormwater runoff, surface spills and leaking waste pits associated with drilling operations have also polluted springs and streams, most notoriously in Garden Gulch, which drains the Roan Plateau to Parachute Creek. And undisclosed hydraulic fracturing, or “fracking,” chemicals used by energy companies to extract natural gas from local rock formations may be an additional cause for concern. A current study by the Environmental Protection Agency is examining the potential health and environmental effects of fracking, with initial results expected in 2012.
In the upper river, Gunderson and dozens of others continue to look for ways to manage metals, such as cadmium and zinc that leach from dozens of abandoned mines into the rivers. The state maintains what’s known as a “303(d) list,” a tabulation of stream segments where water quality standards are not being met. In all, 1,797 miles of the mainstem Colorado Basin’s streams are on the state’s 303(d) list for various impairments, many of them appearing because of runoff from old mines—or for exceeding temperature limits.
“Having more water would be the ideal way to deal with some of this,” says Klancke, “but we’re dealing with a de-watered river.”
Adapting to an Altered River
Bruce Talbott, a fifth-generation fruit grower in Palisade, is one of the largest growers in Mesa County. He’s also part of the reason Colorado harvests the nation’s seventh largest peach crop and is famous for its Palisade peaches.
He would like to see any new water developed from the Colorado be placed in a new storage project for the farmers of the West Slope so that they can augment streamflows to help maintain water quality, minimize water shortages and possibly expand irrigated acreage.
Like Mel Rettig, he carefully manages soil chemistry. He’s altered his fruit crops and spread expensive chemicals to bring down pH levels in the soil. He irrigates his peaches and grapes from five different canals, and he also diverts directly from the river. He’s battled river water so filled with debris that it clogs his diversion structures.
“We live in a high desert and that’s just the kind of water we get,” Talbott says. “But I am always reluctant to see our best water go to the other side of the hill.”