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.
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.
An expanded Gross Reservoir will destroy the environment.
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.
Denver Water is increasing the size of the National Forest System.
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.
650,000 trees will be removed to make way for this project.
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.
Permitting authorities must select the Least Environmentally Damaging Practicable Alternative (LEDPA).
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.
Noise from the project will not exceed Boulder County noise standards.
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.
A taller dam will damage aquatic conditions in South Boulder Creek
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.
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