Gross Expansion Project – A good thing?


Denver Water is projecting potential water shortfalls of 34,000 acre-feet of water (How much water is that?). They hope to meet nearly half of that shortfall (16,000 acre-feet) with conservation efforts. Although many have suggested that Denver water conservation is just really conversation and therefore hot air. In addition to the shortfall there are issues of reliability and vulnerability. In the 2002 drought the Moffat Collection System almost ran out of water, which would have made folks in Arvada and Westminister cranky and parched. The vulnerability exposure is because 80% of Denver water supply depends on unimpeded operation of Strontial Springs Reservoir. I guess Denver Water sphincters got a little tight during the Hayman and Buffalo Creek fires.

The Army Corps of Engineers is currently reviewing five alternatives for coming up with the rest of the water. The lead alternative being heavily pushed by Denver Water is called Large Gross. Simply put, the plan is to raise the top of the dam 125 feet to bring Gross Reservoir to its originally designed size of 114,000 acre feet. That’s an increase of 72,000 acre feet. Why so much? Denver Water has determined that you need 4 acre-feet of storage for every 1 acre-foot of supply. How’d dey do dat? I dunno. Since this was the originally designed size, no improvements to the Moffat Tunnel or South Boulder Canal are needed. Likewise, no additional water rights are needed. And, as near as I can tell, there is no requirement for a public vote (approval) of the project. There are two licenses that need to be acquired … more on that later.

That’s it for the simple stuff.


“Raising the dam 125 feet…” hee hee. This an enormous engineering project that really means building a brand new dam from the bottom to beyond the top of the old one; roughly twice the volume of the existing material (800,000 cubic yards). Estimated cost $140,000,000 and construction time starting in 2013 about 3 years. Some folks think that these estimates were created by engineers who are not sharing their drugs.

Much of the material will be quarried on site … 24 hours a day for 3 years, 4 years, 5? The folks on the hillside in this picture are really looking foward to that.

The rest of the material will come from Front Range Quarries on gravel trucks (average 20 trucks a day) via hwy 72. The folks living in Coal Creek, Crescent Meadows, etc are simply estatic about that.

Denver Water Construction Info including Potential Haul Route

New water level map with proposed dam

grand county impact/mitigation

While it is clear that the folks surrounding the construction and in Coal Creek canyon are going to suffer for several years so that the folks in Arvada and Westminister can have Kentucky Blue Grass, it is a bit of a muddle with regards to the Western slope waters (Fraser, Williams Fork, Colorado.) The charts from Denver Water are (not surprisingly) quite favorable to the project. In fact, one chart projection for the Fraser (based on the Tabernash gauging station) pointed out that the extra water would only be diverted from the Fraser in average or wet years and in accordance with natural stream flows. The difference in the stream flow before and after the diversion is quite small and by all appearances acceptable. The equivalent chart for the gauging station closer to winter park was not available. I am supposed to be receiving both of these charts from an Environmental Planner at Denver Water. I will post them when I receive them.

Fraser below Taberhash

What is clear is that Denver Water has put a lot of effort into mitigating impact to Grand County. The residents in attendance from Grand County are not very trusting that this effort will be fruitful and are justifiably concerned about reduced flows, water clarity due to nutrient/sediment imbalance in rivers, loss of not-so-well known streams like St. Louis Creek, and indirect impact to already stressed waters like Grand Lake. The slickness of some of the displays or Denver Water executives erodes the credibility of their data.

WW to SLICK DENVER WATER EXECUTIVE in front of display of mitigation plans…
WW: “These numbers are impressive. But some of them appear to be ‘black magic’. For example, how are you going to give back 2,000 acre-feet water to Grand County?”
SDWE: “Actually, that is black magic. This is water we already own and we are offering not to take it.”

Licenses and timeline

It may be my personal paranoid tendencies, but I think the license issue is one of the “tricks” that makes this so appealing to Denver Water. In the past, when Denver Water has tried to do large water storage projects like Two Forks Dam, they have run into the brick wall known as “public approval.” For the Large Gross project it does not appear that they have to worry about that because it is an expansion of an existing project. To get this going they need an ammendement to a license and they need a permit. The approval of their ammendment of their hydropower license comes from the Federal Regulatory Commission (FREC). The permit comes from the Army Corps of Enginneers based upon the Environmental Impact Study. Public involvement, such as the on-the-record public comments last Tuesday, is part of this process, but public approval is not.

One severely irritated lawyer at the meeting said that Corps was in violation of the National Environmental Policy Act (NEPA) and that the only way to stop this project was to take them to court based on that contention. His view was that the need for this project was vastly overstated and if Denver Water changed it’s reliablility requirement from 1 drought year in 50 (he said higher than average) to 1 drought year in 25 (supposedly closer to average), than this problem simply vanishes. I have no idea where the truth is here.

  • October 2009 – Draft Environmental Impact Statement and application to FREC
  • Fall 2009 – Public Comment
  • 2010 – Permit acquired and license ammendment approved
  • 2010 to 2012 – Design Phase
  • 2013 to 2016 Construction Phase

South Boulder Creek Flow

On minimum flows…
SHARP YOUNG DENVER WATER PLANNER: “[long technical explanation of DOW’s minimum water calculations and how it is applied to South Boulder Creek.]”
WW: “I don’t really understand what you said but after years of study I have determined that fish like water. Furthermore, I believe 10cfs is approximately 30% better than 7cfs.”
SYDWP: “Yes, but 7cfs is infinitely better than zero.”

I really enjoyed meeting this engaging young man, who seemed to know the most about the project, impact, and pretty much everything. And, with his help, I think I now understand how the water flows decisions are made for South Boulder Creek below Gross Reservoir and below the South Boulder Canal diversion to Ralston Reservoir.

The South Boulder Canal comes out of South Boulder below Ethel Herrod trailhead and above Eldorado State Park. It diverts water to Ralston Reservoir which is located south of Hwy 72 and just West of Hwy 93. The dam of that reservoir is visible from 93. Water is sent through that canal to fill Ralston and to keep the canal from freezing. When Ralston is full or the canal needs repair or clearing of debris no water goes through it. When this water is diverted, depending on what’s coming out of Gross, the remaining water left for SBC through Eldorado and below can be at garden hose level.

The water flow that comes out of Gross is determined by the need to fill Ralston, agricultural requirements, the need to store water in Gross, in-flow to Gross. The in-flow to Gross is by way of SBC. That flow is frequently augmented from the Moffat tunnel which diverts water from the Fraser and other creeks in that valley.

If there is no need to store water in Gross, no need to divert water to Ralston, the flow out of Gross should equal the natural flow of water from SBC into Gross.

One of the benefits of the Large Gross project is that there should be more water availble for SBC below Gross and below the SBC canal diversion. Additionally, the cities of Boulder and Lafayette are close to an agreement with Denver Water to reserve 5000 acre-feet (How much water is that?) for SBC below Gross, through Eldorado Canyon and beyond.

Personal Take

This project is based on an inevitably calamitous assumption that Denver Metro be allowed to grow unrestricted. It’s arid environment cannot support that assumption and at some point in the future, it will become tragically obvious. Furthermore, incremental water conservation steps have been abysmal. Watering restrictions should remain in place permanently and the addition of non-indigineous grasses should be prohibited. As our fellow Colorado citizens who live west of Denver are fond of saying, “Denver has to learn to live within its [environmental] means.”

In my first face-to-face meeting with Denver Water in the early 1970s, I raised this issue. Their response was, “That’s not our call. Our job is to make sure the projected population has the water it needs.” In 35 years, that has not changed. It is the job of our elected officials, and by implication us, to make intelligent solutions about our future survival. That does not appear to be within our skillset. Whereas, rampant development for economic gain is.

Therefore, within the context of the goals of Denver Water, there are a lot of positive elements of the is project; assuming their data is correct. I am not clear on what the oversight controls, if any, are for that data. There are significant negative elements as well. The quality of life impact for those who have chosen to enjoy the pristine character of Coal Creek Canyon, Crescent Meadows, Gross Reservoir, and Grand County will likely be severe. On a comparatively minor note, what will be the impact on the SBC water below Gross during construction? What about the sheer increase in noise in the area?

It would be nice to find out if the irriated lawyer was correct and that his project is indeed unnecessary.

While this may be the best “engineered” plan for Denver’s current water problems, it is based on the false assumption that Denver can use as much water as it desires.

Overheard Tuesday night …
“We tried to come up with a plan that made a few people a little mad, instead it made a lot of people furious.” – Denver Water employee

As seen on Mudbug Co


Wallace Westfeldt