Gross Reservoir Expansion Project

The Big Picture

Just like they did on the Two Forks Project in 1990, the Environmental Protection Agency (EPA) will veto and stop this project.

Click to Flip

Fiction.

In this June 2017 letter to the U.S. Army Corps of Engineers, the EPA’s Acting Regional Administrator states explicitly:
  • The EPA compliments the Corps’ team for addressing all of the EPA’s comments in a professional and efficient manner
  • The EPA will not (emphasis ours) be requesting a higher level of review of the Corps’ decision
  • That diversions of West Slope water to the Front Range will not (emphasis ours) result in significant degradation of West Slope watersheds

Denver Water customers need to conserve more.

Click to Flip

Fact.

We wholeheartedly agree with that statement, which is why we continue our industry-leading and nationally-recognized conservation program. The reality of the situation – as it relates to expanding Gross Reservoir – is we can’t simply conserve our way to a secure water future. Our “all of the above” approach includes promoting use of recycled water, driving conservation, and responsibly sourcing additional supply – which includes expanding Gross Reservoir.

Denver Water should make plans with the goal of limiting growth.

Click to Flip

Fiction.

Denver Water doesn’t have the authority to control or manage growth. It is our job to plan for future needs of our customers, so we rely on outside experts (such as DRCOG) to provide population estimates and plan accordingly.

Since its design in the early 1950s, Gross Dam was always intended to be raised.

Click to Flip

Fact.

Denver Water archives show Gross Dam was always intended for two subsequent dam raises. Current plans call for these to be completed in one so the full storage capacity of Gross Reservoir can be realized.

Additional water taken by an expanded Gross Reservoir will cause our state to default on our obligations under the Colorado River Compact Agreement.

Click to Flip

Fiction.

The expected yield to be stored in an expanded Gross Reservoir will not impact our ability to fulfill our obligations. Besides, if the small amount of yield this project plans to gain from the Fraser River during future wet years were of concern to downstream users and threatened compact obligations, why have no objections been raised by those with legal standing during the 14-year period the project has been in the planning and permitting stages?

Denver Water doesn’t have the ability to treat all the water they plan to collect and store in an expanded Gross Reservoir.

Click to Flip

Fiction.

Our water treatment facilities currently have the capacity to treat water to meet needs of our customers into the future. Also, we are in the design phase of the new Northwater treatment plant as part of our larger North System Renewal Program, which will provide up to 150 million gallons of water per day for our customers.

An expanded Gross Reservoir will never fill because – according to climate models – there won’t be enough water in key West Slope watersheds.

Click to Flip

Fiction.

This myth is supported by an analysis that uses a different time period, different assumptions, different data and a different model than the hydrologic analysis conducted by independent experts that was published in the Army Corps of Engineers’ Environmental Impact Statement (EIS). The flawed methodology used by opponents invariably produces results that differ from the model adopted by those with competing water interests on both sides of the continental divide. Further, the Corps found opponents’ attempts to compare results were inaccurate and misleading. (Source: Corps FEIS, Attachment B, Page 17)

The only certainty is an uncertain future and the Gross Project will allow us to better adapt and provides greater flexibility than our current situation.

Denver Water didn’t learn anything from the Environmental Protection Agency’s veto of the Two Forks Dam project in 1990.

Click to Flip

Fiction.

We learned a lot, actually, which has informed our plans and actions ever since, and led to our industry-leading and nationally-recognized conservation program, pioneering the use of recycled water, and responsibly sourcing additional supply.

Failing on Two Forks was an inflection point; one where we made the conscious decision to listen more. Listening is, in part, how we arrived at expanding Gross Reservoir, as environmental groups who opposed Two Forks recommended raising Gross Dam as an alternative. The fact that Gross Reservoir was designed from the beginning for two subsequent dam raises was a contributing factor in it being selected as the preferred alternative over more than 30 that were considered.

There is an active fault located beneath the reservoir.

Click to Flip

Fact AND Fiction.

There are faults beneath Gross Reservoir, but they are not active and do not pose an earthquake threat. Chapter 5, page 5-204 of the Final Environmental Impact Statement reads “…the Livingston Sheer Zone and Fault, the Copeland Fault, and the Rogers Fault are not mapped as potentially active and therefore unlikely to create earthquake activity near Gross Reservoir.” Faults that have been identified in the vicinity of the dam have been deemed inactive so there is little chance that the activation of theses faults is possible. Nonetheless, Denver Water will conduct detailed geotechnical and seismic studies in the design and construction phases of the project.

Environmental

The project hasn’t adequately studied impacts to Walker Ranch Open Space.

Click to Flip

Fiction.

This issue was studied thoroughly and there will be no direct impacts to the Walker Ranch Open Space or any other Boulder County Open Space land ( Final Environmental Impact Statement, Chapter 5, page 5-450.). However, there will be short-term, indirect effects to users of Walker Ranch due to noise and visual effects of the construction activities. In addition, Per the Final Environmental Impact Statement, Chapter 5, page 5-290, “The Hawkin Gulch/Walker Ranch/Upper Eldorado Canyon Environmental Conservation Area (ECA), located below the dam, would not incur impact under the Proposed Action or any other action alternatives.”

There’s a geologic fault line that runs beneath Gross Dam and that fault will become active when the height and mass of the dam is increased.

Click to Flip

Fact AND Fiction.

There are faults beneath Gross Reservoir, but they are not active and do not pose an earthquake threat. Chapter 5, page 5-204 of the Final Environmental Impact Statement reads “…the Livingston Sheer Zone and Fault, the Copeland Fault, and the Rogers Fault are not mapped as potentially active and therefore unlikely to create earthquake activity near Gross Reservoir.” Faults that have been identified in the vicinity of the dam have been deemed inactive so there is little chance that the activation of theses faults is possible. Nonetheless, Denver Water will conduct detailed geotechnical and seismic studies in the design and construction phases of the project.

Denver Water is increasing the size of the National Forest System.

Click to Flip

Fact.

Denver Water will convey approximately 540 acres of land near the Moffat Tunnel, which includes forest, riparian, and wetland habitats, to the United States Forest Service for permanent protection and management as part of the National Forest System (NFS). This land conveyance represents mitigation for impacts to approximately 280 acres of NFS land that will be inundated by the Gross Reservoir expansion. Stated simply, Denver Water will provide nearly a 2:1 mitigation ratio of replacement acreage transferred to the U.S. Forest Service to offset those acres of NFS land that will be lost due to the expanded reservoir footprint.

A taller dam will damage aquatic conditions in South Boulder Creek

Click to Flip

Fiction.

Environmental studies show that water temperature at the reservoir outflow is generally in the acceptable range for trout today, and will be similar in the future once the expansion is completed.

Currently, the biggest threat to aquatic life in South Boulder Creek is lack of water, not water temperatures. As it stands today, there are times of the year when some portions of SBC run at water levels insufficient to maintain aquatic life. An expanded Gross Reservoir will include space for an environmental pool, which will be managed by the cities of Boulder and Lafayette. The intent of this is to enable release of water during low flow periods so SBC will have life sustaining flows year-round.

Learn more here.

An expanded Gross Reservoir will destroy the environment.

Click to Flip

Fiction.

We have worked very hard to avoid that. The State of Colorado has studied the likely impacts, compared these with the mitigation and enhancements we have committed to as conditions of various agreements and permits, and found the project will have a "net environmental benefit" for Colorado. That is one of many reasons why the project is endorsed by Gov. Hickenlooper and the last four governors of our state, along withstate and federal lawmakers, major environmental groups, local mayors and city councils, chambers of commerce and economic development corporations, county elected officials and water interests on both sides of the divide.

650,000 trees will be removed to make way for this project.

Click to Flip

Fact AND Fiction.

Trees will need to be removed to expand Gross Reservoir, though the figure is likely far less than 650,000 according to Boulder District Forester Allen Owen. He told the Daily Camera that “the number seems high". Denver Water uses this most conservative, worst-case scenario because we want to work in good faith and be transparent. The loss of these trees is considered and accounted for in the multi-year environmental review and permitting processes this project has required.

Removal techniques and the final plan will be studied more thoroughly in the coming years and will include public input to minimize inconvenience. New environmentally friendly disposal technologies that didn’t exist when the initial plan was developed will be evaluated and pursued if found to be beneficial. If hauling is required, trucks hauling materials will use the same route – albeit in reverse – as those hauling materials to the site. In other words, we will use Gross Dam Road and State Highway 72; we will NOT use Flagstaff Road or transport through Boulder.

Noise from the project will not exceed Boulder County noise standards.

Click to Flip

Fact.

Denver Water is committed to monitoring noise impacts and conforming to all applicable local codes and regulations. The noise study, performed by independent experts, finds all work can be completed without exceeding noise standards set by local authorities. We will work with neighbors and use best management practices and mitigation technologies to reduce noise impacts to the greatest extent possible.

Permitting authorities must select the Least Environmentally Damaging Practicable Alternative (LEDPA).

Click to Flip

Fact.

Expanding Gross Reservoir is the Least Environmentally Damaging Practicable Alternative (LEDPA). According to page 15 of the US Army Corps of Engineers’ Record of Decision, “The Section 404(b)(1) Guidelines require the Corps to identify the (LEDPA). The Corps has identified (Denver Water’s) Preferred Alternative, including the Environmental Pool, as the LEDPA. The Corps LEDPA determination would not change if the Environmental Pool was not included in the construction and operation of (Denver Water’s) Preferred Alternative.” Denver Water has committed more than $20 million to more than 60 different environmental projects on both sides of the divide that will be carried out as components of the Gross Reservoir Expansion project. According to the state of Colorado, those commitments will have a net environmental benefit for our state.

Latest News / Blog

Breathtaking work nearly 300 feet underwater

August 23, 2021 - TAP - Major project replacing large debris grate at Gross Dam requires experts in the harrowing field of saturation diving. Raitt stresses the project is wholly unrelated to the planned expansion of Gross Reservoir. It would be happening regardless...

All the ways we save (It’s not just shorter showers!)

August 6, 2021 - TAP There are a few things many customers might know about Denver Water’s efforts to use water efficiently. There was that fun and flashy and very effective 10-year “Use Only What You Need” campaign that cut per person water use by 22%. Denver Water...

Could Colorado cities save enough water to stop building dams?

Aug. 6, 2021 - Colorado Sun - Conservation groups want more “cash for grass” and other plans to acquire new water by saving it. But Denver and Aurora, among others, say there’s only so much to cut before a new dam is needed. Denver Water, serving 1.5 million customers...

A gleaming gift to the great outdoors

July 29,2021 - TAP - Denver Water conveying stunningly scenic parcels to Forest Service as part of Gross Reservoir Expansion Project. Denver Water is in the process of conveying 539 acres of wetlands, meadows and forests in Gilpin County to the Forest Service to be...