Adams County, named after former Colorado Governor Alva Adams, encompasses 1,184 square miles in northeast Colorado. A long, irregular rectangle, the county stretches across the plains from its western boundary north of Denver to its eastern edge at the intersection of US Route 36 and Meridian Road. It is bordered on the north by Weld and Morgan Counties, on the east by Washington County, on the south by Arapahoe County, and to the east and southeast by Jefferson and Denver Counties. Before the arrival of whites in the nineteenth century, Native Americans had claim to the county’s current area. In 1859, the first white settlers moved to the area that would become Brighton, the current county seat.
The county supports a population of more than 440,000, making it the fifth-most populous county in Colorado. Most of its population is concentrated in the Denver metro area, in the cities of Arvada, Aurora, Commerce City, and Thornton. Commerce City is home to Dick’s Sporting Goods Park and of the Colorado Rapids of Major League Soccer, as well as of the Suncor Energy oil refinery, currently the largest oil refinery in the Rocky Mountain Region. Natural areas in the county include Barr Lake State Park, near Brighton, and the Rocky Mountain Arsenal National Wildlife Refuge.
Indigenous People and White Immigrants
By the early nineteenth century, present-day Adams County was home to the Cheyenne and Arapaho people, who had come to the region after being pushed out of their traditional homelands in the Midwest. The two allied groups shared a nomadic lifestyle based on the horse, which among other advantages allowed them to hunt buffalo with greater efficiency and to quickly find shelter during storms, a threat in every season on the turbulent Great Plains. The Cheyenne and Arapaho also had a common enemy in the Utes, who frequently rode out of the mountains to hunt buffalo. During the worst extremes of summer and winter on the plains, cottonwood stands along the South Platte River and its tributaries provided food and shelter.
By the 1820s, European fur trappers and traders were active in the region, and in 1850 Lewis Ralston made the first documented gold find in Colorado along Ralston’s Creek (today’s Clear Creek) in present-day Arvada. Little came of the find, however, as the Cheyenne and Arapaho still held dominion over the area and the nation was fixated on the California Gold Rush farther west.
Conditions were different in 1858, when gold was discovered along Dry Creek in present-day Denver. The US Army had won small but symbolic victories against hostile Native Americans on the plains, and the Treaty of Fort Laramie in 1851 provided for the protection of wagon trains headed west. As the news of the find traveled east, whites began streaming into the Denver area across overland wagon routes from Kansas. In 1859 two of these emigrants, Benjamin Wadsworth and Louis Reno, platted the town of Arvada near the site of Lewis Ralston’s find nine years before. An irrigation ditch was dug, and farming began within a year.
Native American Removal
The arrival of so many whites put pressure on the Native Americans’ resource base, as travelers shot buffalo and used the valuable cottonwoods for fuel and shelter. The houses, fences, and crops of white farmers and ranchers took wood and water from the all-important groves along the Platte and its tributaries, and cattle herds ate up acres of prime grazing lands. Conflict stemming from this invasion of people, animals, and plants prompted the federal government to seek solutions. In 1861 a reservation was established in southeastern Colorado for the Cheyenne and Arapaho, but by this time the Indian bands were split between those who favored capitulation to the whites and those who favored resistance and war.
In 1864 US troops massacred more than 150 peaceful Arapaho and Cheyenne at Sand Creek in Kiowa County, prompting more than a decade of warfare between the US military and an alliance of Arapaho, Cheyenne, Lakota, and other Plains Indians. In 1867, the Medicine Lodge Treaty established the Cheyenne-Arapaho Indian Reservation in central Oklahoma, then known as “Indian Territory.” Though sporadic raiding by the Arapaho and their allies continued into the 1870s, by the end of the nineteenth century Adams County was mostly cleared of both groups.
County Formation and Development
From 1861 to 1901, the area now known as Adams County was included in Arapahoe County. In 1876, the Colorado Territory became the state of Colorado. The thirteenth legislative assembly effectively renamed much of the eastern part of the original Arapahoe County as Adams County in 1901, and Adams County’s original borders extended east from north Denver to the Nebraska border. However, the fourteenth assembly extended the southern boundaries of Washington and Yuma counties, cutting off the eastern boundary of Adams County at a spot roughly twenty miles southeast of Fort Morgan.
In 1870–71 the Boulder County Railroad linked with the Denver Pacific Railroad at Hughes Station. The town of Brighton developed around the station and incorporated on May 6, 1887, with 175 residents. Upon incorporation, the small town featured a school, a church, a blacksmith, a hotel, a market, saloons, and a newspaper. Brighton was designated the permanent county seat in 1904.
Water from the South Platte has allowed agriculture to be a mainstay of Adam County’s economy since the mid-nineteenth century. With the explosion of sugar beet farming along the northern Front Range around the turn of the century, the county experienced an influx of Hispanic farm laborers, many of whom were fleeing revolutionary turmoil in Mexico. In 1917, farmers and merchants in the county convinced the Great Western Sugar Company to build a beet-processing factory in Brighton, which stayed in operation until 1977.
In 1947 Adams/Arapahoe County farmer Frank Zybach developed center-pivot irrigation, a watering technique in which a row of sprinklers is mechanically driven around a center well. Before Zybach's invention, one irrigation worker could tend 400 acres; with center-pivot technology the same worker could water 1,600 acres. Today center-pivot is the dominant irrigation method in Colorado, and more than 250,000 systems are in use around the world.
Cession of Land
In a 1989 election, Adams County granted fifty-three square miles of its southwest corner to Denver for the construction of Denver International Airport (DIA). By the late 1990s, the city of Broomfield had grown to encompass territory in four different counties, including Adams. In 2001, this confusing administrative structure was settled when the city and county of Broomfield was established, taking another small chunk out of Adams County.
Like other places in Colorado and the west, Adams County was a site of contention between economic and environmental interests throughout the twentieth century. Perhaps as a result of that history, Adams County today has demonstrated an ability to balance traditional economic development—factories, oil refineries, and sports complexes—with more sustainable endeavors, such as wildlife refuges and solar energy sites.
In 1942, the US Army built Rocky Mountain Arsenal, a $10 million, 17,000-acre chemical weapons facility about ten miles northeast of Denver. After World War II, the army began leasing some of the arsenal’s facilities to private companies. From 1952 to 1982, Shell Oil used some of the buildings for the production of agricultural herbicides and pesticides. During the Cold War, the army reactivated the arsenal for weapons production, and the facilities also produced the rocket fuel used by the Apollo 11 space expedition.
Years of weapons and chemical production at the arsenal had a devastating effect on the local environment. Over three decades, both the army and private industries deposited millions of gallons of liquid waste into natural depressions on the site. Beginning in the 1950s, farmers on land surrounding the facility noticed sick livestock and crop damage, caused by leakage of herbicides and pesticides from the arsenal. In 1975, the Colorado Department of Health found that surrounding lands were contaminated with diisopropylmethyl-phosphonate (DIMP), a compound used in nerve gas, and dicyclopentadiene (DCPD), a chemical used in adhesives and paints. Overall, more than 750 different chemicals were used on-site, and some 8 to 13 million cubic yards of soil are estimated to have been contaminated by arsenal operations. In 1982, the army and Shell stopped all chemical production at the facility, and by 1988 the army had prioritized cleanup of the site.
In 1987, the US Environmental Protection Agency (EPA) designated the Rocky Mountain Arsenal as one of its “superfund” sites, or high-priority cleanup sites. Cleanup operations, overseen by the army, Shell, and the EPA, cost $2.1 billion and were completed by 2010, although groundwater treatment is ongoing. After the surface cleanup, the army transferred arsenal land to the US Fish and Wildlife Service to create Rocky Mountain Arsenal National Wildlife Refuge. The refuge today encompasses 15,000 acres of short-grass prairie and is home to more than 300 species of wildlife.
In the mid-2000s, billionaire sports franchise owner Stan Kroenke, in partnership with Commerce City, developed plans for a $131 million stadium complex at the southwestern edge of the Rocky Mountain Arsenal reserve. Construction of Dick’s Sporting Goods Park was finished in 2007. In addition to being the home of the Colorado Rapids, Kroenke’s Major League Soccer club, the 18,000-seat stadium serves as a venue for concerts, festivals, and a variety of national and international sporting events, including US national soccer team matches. Beyond the stadium, the 917-acre site hosts business offices for Commerce City staff and the US Fish and Wildlife Service, as well as a visitors’ center for the nearby Rocky Mountain Arsenal Wildlife Refuge.
Another source of pollution in Adams County is the Suncor refinery, established in Commerce City in the 1930s. The facility refines nearly 90,000 barrels of crude oil per day, with some of the crude coming from local sources and some from Canadian tar sands Since the 1980s, the refinery has been known to exude toxic waste, including benzene, a known carcinogen. In November 2011, a local fisherman reported a black ooze seeping into the South Platte River. The Denver Post later reported that both the company and the state health department had known about the uncontrolled spill for months. The EPA investigated and launched an emergency cleanup, finding benzene contamination levels in the South Platte and Sand Creek between 480 and 2,000 parts per billion—significantly higher than the EPA’s national drinking-water standard of 5 ppb.
In April 2012, Suncor settled with the Colorado Department of Public Health and Environment for $2.2 million, covering cleanup costs and penalties for air pollution. Among other violations incurred between 2008 and 2010, the refinery’s airborne benzene emissions were found to be 3.34 metric tons above the amount considered safe by federal health standards. In May, the Post reported that efforts to clean up the aquatic benzene plume, including aerating contaminated water to push out the benzene, had been largely unsuccessful; the newspaper noted that benzene levels in some parts of Sand Creek and the South Platte River had more than doubled in a month’s time. Suncor continues to oversee prevention and cleanup operations, which include maintaining an underground wall to stop seepage and treating contaminated water and soils.
A Brighter Future
While the Suncor oil refinery cleans up its toxic waste, Adams County is entering the renewable energy market. In September 2014, the county became one of the first in the nation to implement a community solar panel program when it entered into a partnership with SunShare, a Denver-based solar energy company. The company plans to install solar gardens—large arrays of solar panels—near Forty-Eighth Avenue and Imboden Road. When completed, Adams County will purchase approximately 189 kilowatts to power its municipal buildings, which are estimated to make up 5 percent of the county’s total electricity demand.
County sustainability manager Nick Kittle claimed that the partnership will save Adams County nearly $300,000 in energy costs over the next twenty years, and that county homeowners will be allowed to purchase SunShare solar energy after the benefits for the municipal buildings are evaluated. The county and other potential SunShare customers will receive credits for the solar power on their Xcel Energy bills.