BOULDER COUNTY, Colo. (CBS4) – Denver Water is suing Boulder County over application processing delays in the Gross Reservoir Expansion Project. In a complaint filed Wednesday in U.S. District Court, Denver Water claims Boulder County overreached its authority through repeated requests for information about the project.

Gross Reservoir (credit: CBS)

“For years, Denver Water has also attempted good faith efforts to work with Boulder County to secure county permits, including through two attempts at an intergovernmental agreement, robust engagement with county staff and neighbors, and participation in a local land-use review known as the “1041 process.” Unfortunately, Boulder County has been unreceptive and is using the 1041 process to frustrate the project, extending and delaying its review to the point that it is now placing the entire project at risk,” stated Denver Water in a news release.

Denver Water received federal approval to proceed with the Gross Reservoir expansion in July 2020. The process to obtain environmental permits for the $380 million project began in 2003.

Gross Reservoir (credit:

The project aims to balance water supplies and enhance water security for more than 1.5 million people. The enlarged dam will increase the capacity of the reservoir by 77,000 acre-feet, and includes 5,000 acre-feet of storage dedicated to South Boulder Creek flows that will be managed by the cities of Boulder and Lafayette.

The Colorado Department of Public Health and Environment approved the project in 2016, followed by the U.S. Army Corps of Engineers in 2017. Environmental groups sued to block the expansion in 2018, claiming the U.S. Army Corps of Engineers violated environmental laws when it granted a permit to increase the height of Gross Dam by 131 feet.

In 2019, a district court judge sided with Boulder County’s request to review the project. Denver Water filed to appeal the ruling.

Boulder County Attorney Ben Pearlman issued the following statement to CBS4 on Wednesday evening:

“Denver Water’s new lawsuit comes as a surprise because just two weeks ago, county staff informed Denver Water that the county had scheduled hearings in front of the Boulder County Planning Commission in August and the Board of County Commissioners in September, despite Denver Water’s unwillingness to provide all the information County staff had requested. The County hasn’t been served with the lawsuit. The County Attorney’s Office will review the claims and file a thorough response at the appropriate time.”