Colorado Settles Rocky Mountain Arsenal Suit

DENVER – Colorado Attorney General John Suthers and Governor Bill Ritter today announced the settlement of Colorado’s quarter-century-old claim for natural resource damages at the Rocky Mountain Arsenal Superfund site. The State has reached agreements in principle with both Shell Oil Company and the United States Army that will result in over $35 million in acquisition, enhancement, and restoration of natural resources in and around the northeast metro area Arsenal site.

“When I entered the Attorney General’s Office in 2005, resolving the State’s claim at the Rocky Mountain Arsenal was one of the highest priorities for my tenure as AG,” commented Suthers. “As a result of very focused cooperation from Shell and the U.S. Department of Justice, we have made tremendous progress in negotiations over the past several months, and I am very pleased today to announce the largest natural resource damage settlement in Colorado history.”

"This is a historic settlement -- an accomplishment achieved through strong collaboration led by the Attorney General's Office, the Colorado Department of Public Health and Environment and the Department of Natural Resources," Gov. Ritter said. “I applaud their commitment and hard work, which allows us to celebrate this milestone today. The funding contained in this settlement will provide long-term compensation to the citizens along the South Platte who have been affected by the natural resource damages at the Arsenal. I also want to commend the local elected officials, Great Outdoors Colorado, the Division of Wildlife, State Parks, the Northeast Greenway Corridor project and the many other people and organizations who have supported the efforts to resolve this matter.”

 “This settlement is the culmination of years of effort by the State of Colorado, including my efforts as Colorado Attorney General, to obtain relief for the natural resource damages incurred at the Rocky Mountain Arsenal,” said Senator Ken Salazar.  “I congratulate Attorney General Suthers, his legal team, the Army and Shell for today’s resolution of this dispute. Additionally, these settlement funds may help implement the vision of a metro northeast greenway corridor that I have worked with the area’s local governments, the AG’s office and with the state to create in an effort to preserve open space and wildlife habitats, restore water resources and provide new recreational opportunities for our citizens.  The Rocky Mountain Arsenal is the lynchpin to that vision, the centerpiece of these adjacent regional preservation and restoration efforts.”

As part of the agreement, Shell will pay $10 million in natural resource damages, monies that will be administered by the state’s Natural Resource Trustees for restoration projects on or near the Arsenal site. Shell will also donate an additional $10 million to a state natural resource foundation that will be used to fund projects in the Northeast Greenway Corridor. Additionally, Shell will donate approximately 100 acres of land in the First Creek corridor – with an estimated value of more than $1 million – to Commerce City to serve as a gateway for a planned trail system linking open space along the South Platte River. 

For its part of the settlement, the United States will pay $7.4 million in natural resource damages to be used for restoration projects. To complete its obligation, the federal government is entitled to a credit of $6.6 million for the 1989 construction of the Klein water treatment plant, located just north of 72nd Avenue and Quebec Street. 

RMA Settlement at a glance

Natural Resource Damages

$17.4 million


$10 million


$7.4 million

NE Greenway donation from Shell

$10 million

Completed project credit from Army

$6.6 million

Land donation by Shell

> $1 million


> $35 million

The parties were able to make significant progress in negotiations as the State began to develop a better understanding of which natural resources are still affected by contamination and how much those resources are worth – a process that began in early 2005. Using $2.4 million in funds provided by the Colorado General Assembly, the State carefully assessed the remaining plume of affected groundwater and the rate at which it is shrinking. It became evident as the assessment process progressed that the remaining contamination is not as widespread as originally thought.

The Rocky Mountain Arsenal settlement is by far the largest natural resource damage settlement in the history of the state, easily surpassing the $10 million settlement for Rocky Flats. The State’s 1983 lawsuit against Shell and the Army has been one of the longest-running litigations in the history of the Attorney General’s Office. 

The settlements reached with Shell and the Army will provide fair compensation to the people of Colorado for the past and current injuries to natural resources, while enabling the State to reap the benefits of restoration in the near future. Further, the settlement obviates the need for the State to spend millions of additional dollars and many more years litigating the case for an uncertain result. Finally, the settlements will allow for the protection of threatened land parcels in areas around the Arsenal before they are forever lost to development.

Background on the Arsenal site

The Rocky Mountain Arsenal is a federally-owned facility in Adams County, Colorado, just northeast of the Denver metropolitan area and southwest of Denver International Airport. In 1942, the U.S. Army purchased the 27 square-mile property for the manufacture of chemical warfare agents and incendiary munitions, including mustard gas, lewisite, phosgene bombs, incendiary bombs, napalm, and Sarin nerve agent. 

After World War II, the Army leased portions of the site to private industry, primarily Shell Oil Company. Shell manufactured pesticides, insecticides, herbicides, and other chemicals, including dieldrin and endrin, at the Arsenal from 1952 to 1982.

Manufacturing wastes from both Shell and the Army were transported through chemical sewers to on-site disposal basins which often had no, or inadequate, seals to prevent environmental contamination. The State contends that these waste disposal practices resulted in widespread soil, surface water, and groundwater contamination, with plumes of contaminated groundwater spreading off-site. Additionally, many birds and other wildlife died due to chemical exposure. 

The Environmental Protection Agency (EPA) listed the Arsenal on the Superfund National Priorities List in the 1980s, thus recognizing the Arsenal as one of the most contaminated sites in the country and making it a priority for cleanup. To ensure that the State would be compensated for environmental damage, the Attorney General’s Office filed suit against Shell and the Army in 1983. In 1995, an agreement was reached among Colorado, the Army, Shell, the EPA, and the US Fish and Wildlife Service regarding cleanup of the site. Since that time, Shell and the Army have spent more than $2.1 billion in cleanup costs, with completion of cleanup activities expected in 2010. The Rocky Mountain Arsenal now serves as a National Wildlife Refuge.


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