Tag Archives: Dillon Reservoir

Dam Good Flow Control

To string incongruities and absurdities together in a wandering and sometimes purposeless way, and seem innocently unaware that they are absurdities; that is the basis of the American art …” – Mark Twain (How to Tell a Story).

Like most who’ve dwelt for any length of time along the Colorado Rocky Mountains I have a habit of regularly quaffing water through most days. Sometimes copiously. Given our semi-arid climate, mile high altitude and generally active life styles – all circumstances that lead to high rates of water expiration – keeping hydrated is never far from our minds. In fact, in many ways for us just east of Colorado’s mountain divide, water is very important – whether we know it or not.

Typical Weekend Jam on I-70, west of Denver, CO

Typical Weekend Jam on I-70, west of Denver, CO

The westward drive along I-70 from Denver, winding up into Colorado’s scenic Rocky Mountains, can provide both eye-popping and ear-popping exhilaration. The type of high elevation experience you get depends largely on the wild mountain weather, road conditions, time of day, your attitude, and – sometimes – flow control. Traffic flow control. Sometimes it moves swiftly; yet often it slows to a crawl (or slower) … so popular and loved are these mountains. And subject to the whims of weather.

A very few miles after you exit the Eisenhower Tunnel [1] (completing your passage under the continental divide), after twisting down and around a few bends, you are treated to the view of the Dillon Reservoir [2]. At about 9,000 feet elevation, and covering over 30,000 acres, the man-made lake lies, more or less, between the mountains of the Great Divide on the east, and the Gore Range and Tenmile Range on the west.

Approaching Dillon Reservoir descending along I-70

Approaching Dillon Reservoir descending along I-70

Most winters find it frozen-over solid for at least part of the season. On summer days its surface is bedecked with sail boats and usually a few kayaks and canoes. Most evenings are clear and you’re likely to catch a lunar reflection, or even a stellar reflection. Buffalo Mountain, magnificently dome-shaped and looming visibly from nearly every point in the Dillon basin, is likely to have a bit of snow on it even in summer. Within all that is a glimpse back into history.

Long before there was a Dillon Reservoir, way back in the first decade of the 20th century, during the Edwardian Era, Denver’s long, lustful and thirsty gaze finally began crystalizing into a vision of conquest: it yearned to own the water of the Blue river basin.

As Denver’s population surged past 150,000 – part of its 50% growth in that decade – and no end in sight to its growth – city planners knew there would always be demand for water. Denver has virtually no physical boundaries to expansion, and it enjoys a dry, semi-arid climate.

The 19th century Colorado gold rushes led Tom Dillon to set up the first settlement near the confluence of three mountain rivers in 1859. These were the Snake River, the Blue River, and Tenmile Creek. The settlement became incorporated into the Town of Dillon in 1883. Much of the population of a few hundred was connected, directly or indirectly, to the extraction of gold, particularly farther south up the Blue River, near Breckenridge.

The town was moved twice, just a mile or two, in order to accommodate better service from rail lines. But, when the gold rush slowed down, the Town of Dillon and the Blue River region stopped growing and slowly began shrinking. Still they hung on … and on. Many people left for Denver or other cities and towns with better prospects, and ranching became the main commerce of the area. A third move for the Town of Dillon – much more significant and decades hence – was yet to come.

The Great Depression gave Denver the opportunity they sought. Dillon’s population crashed: from over 800 to fewer than 100. Denver’s Water Board began buying up the land in and around Dillon at bargain basement prices, primarily via tax liens. When they had 75% it was enough to get serious and file plans with the Federal Government: plans for a great dam across the Blue River. After several rounds of planning and proposals, eventually an achievable and acceptable plan was approved. It included a long, wide earthen dam to be built across a narrow spot in the Blue River valley, just downstream from the three-river confluence.

By the late 1950s the small Town of Dillon’s fate was sealed: its current site would be flooded, deep under a new reservoir, and it would have to endure yet one final move, this time to a hill on a site near the northeast end of a dam yet to be built – far above the river. Many chose not to make the move, instead leaving the area.  At the time of this final move Dillon’s population had dwindled to a mere 57 souls.

The dam itself, which was completed in 1963 and just over a mile in length, is a marvel of engineering and dam good flow control. The flow control consists of four principal flow features.

The first flow control feature is the primary reason for which the dam was constructed. It’s the Harold Roberts Tunnel measuring just over 23 miles long. The tunnel draws water through a 10 foot diameter tube that passes underneath the continental divide, and – with one slight jog – into the North Branch of the South Platte River. As an engineering and geological marvel, the tunnel took about 19 years to complete, beginning in 1942 – although there was some down time for World War II. Once the water enters the South Platte watershed, it is eventually used in the Denver area for washing dishes, bathing, and flushing toilets. About 5% is estimated to be used for landscapes.

Dam flow control feature number two is its hydroelectric plant, operating at nearly 200ft of head. I’m pretty sure it only operates in the late spring and early summer when the mountain runoff is sufficient to keep the reservoir’s level high. At peak it can generate 1.8 Megawatts. If my math is correct, this is enough to provide average electrical power flow to an estimated 1,500 households. [3]

Flow control feature three is actually the primary and most regularly operating feature: gates that permit a fairly steady flow of water downstream to the Blue River of 500 to 1,300 cubic feet per second. The low end keeps both anglers and trout happy; the upper end is achieved during spring run-off and keeps rafters happy. Anything above 1,800 cfs puts the Blue’s channels and rafters at risk. Just very recently flow control feature #3’s six gates were replaced; after 50-years of service they required some updating. [4]

From here the Blue flows generally north, between the Gore Range and the Continental Divide to one more dam, the Green Mountain Dam. This provides more water to the eastern slope via the Colorado-Thompson water project. After another 13 miles, the Blue joins the mighty Colorado River – so mighty it was once called the Grand River – at Kremmling.

Morning Glory Spillway

Morning Glory Spillway

The final form of flow control, feature #4, is sort of a “flow control of last resort” to protect the dam itself. If the water gets much above 9,025 ft elevation the structure of the dam could be at risk. This feature of last resort is the dam’s Morning Glory Spillway, which is set at an elevation of 9,017 feet. The water that “spills” into it, bypasses the gateway and the power plant and goes downstream to the Blue River (This is a few miles from the Thompson Tunnel inlet). [5]

{!!!Warning! This dam feature used to be called “The Glory Hole” – in fact, sometimes local publications still refer to it as such. This term has been used for dams in general for a long, long time. Unfortunately parts of modern culture have appropriated that term for darker usage. If you’d like to find out, go ahead and use an internet search engine – but PLEASE don’t have children in the room. I won’t discuss further and … you have been warned.!!!}

Four main features. That’s a lot of flow control.

The Dillon Dam and Reservoir do a lot more than provide the city of Denver (and its customers and partners) plenty of water… in fact about 40% of their annual water usage, on average. [6] There are ample recreation opportunities too. I’ve mentioned downstream fishing and rafting, as well as sailing, kayaking and canoeing on the reservoir itself.

But there’s more. Around the lake are bicycling, hiking and walking paths. There are parks. There are on- and off-road bike paths with opportunities for wildlife viewing. And there are some campgrounds too.

Near the north bank of the reservoir, just west of the dam itself, is a favorite campground of ours called Heaton Bay. For several years we used to go there at least once a summer. The campground is popular: We’d secure a few adjoining choice sites well in advance for ourselves and some close friends of ours, the Weprins and the Cronks.

Our families and couples (Girards, Weprins and Cronks) are all about the same age, as are our eight combined children. When the kids were all teens we’d love to hangout at the campground for a weekend. The days would be filled with some combination of biking, canoeing, hiking, and grilling. The evenings for BBQ, chatter, singing and beverage sipping. Later at night we’d exchange stories (often scary), drink a bit, and lie on our backs and spot satellites passing overhead, and sometimes the occasional shooting star.

Truth be told, the later hours included burping, farting, and – eventually – snoring.

It was probably about 10 years ago that we three families (read: wives and moms) had just such a relaxing weekend organized. The original plan was to arrive early Friday afternoon, and stay until Sunday afternoon.

Plans always have at least one hiccup. I provided that hiccup. I had some task at work that seemed important at the time … and so I could not leave until mid-afternoon. Long ago I forgot what that task was; but I cannot forget what it caused.

So I stayed at work a few extra hours while the family motored up to Dillon Reservoir. No worries. I could just drive up the mountain later, on my own, through the tunnel, and arrive at Heaton Bay … about 90 minutes after departing … and still avoid rush hour and arrive in plenty of time for dinner.

By 1:30 I’d finished work, gone home, and loaded my car with my clothes and gear pre-staged the evening before. As I left the house I satisfied my usual habit of grabbing a water bottle for the road. It’s important to stay hydrated in Colorado (see above). I was feeling a bit dried out already due to busy day, so I grabbed a bottle that was bit larger than normal for me, at a generous 24-oz (~0.75 liter).

And off I went. I made great time down to Golden, the last town with easy access to gas stations, provisions and facilities, before getting onto I-70. Gosh I was making great time, especially for a Friday. As I passed the last easily-accessed gas station I glanced at my gas gage to ensure there’d be enough fuel to comfortably get up to the mountains.

Even though I had plenty of gas I had that feeling like “maybe everything was not okay.” I checked the dashboard: engine running ok, not too hot. I knew the tires were filled right. All my clothes were packed; at home I’d verified all doors were locked, appliances turned off. I felt I had enough water, even though my bottle was already less than half full.

Had I forgotten something Audrey wanted me to bring? No. What a great day! I guess maybe everything is okay after all.

About 15 minutes later I was dropping down into the last valley outside Genesee Hill on I-70 before heading up to the divide. Traffic was growing a bit thicker, but still moving briskly, when I received a biological tickle that suggested perhaps something was indeed missed back at Golden: the last good chance to take a pee.

No worries. Snappy traffic with sane Colorado drivers and a beautiful clear-sky day. I’ll be in Heaton Bay in well  under an hour.

15 minutes later, I finished the water bottle while rounding a curve and approaching the eastern outskirts of Idaho Springs in the left lane at about 70mph. That’s when I saw it – a tremendous parking lot along the westbound lanes. Everything had come to a complete stop for a far as the eye could see.

Complete. Stand. Still. Now aware of my filling bladder, I wondered if I could force my way off the freeway. No dice: bumper-to-bumper. I’m feeling a little tense.

Five minutes. Ten minutes. Twenty minutes. There really is no way to get out and pee…privately. Traffic news says that recent rains have caused a large mudslide just west of Idaho Springs.

The slide is all the way across both lanes of westbound traffic.

For distraction I call Audrey. I might be late.

Perhaps at this point I wasn’t thinking logically. The adult bladder can comfortably hold up to about 1/3 liter. Uncomfortably perhaps ½ liter, or a bit more. I’d just consumed ¾ liter. Plus I’d had some coffee and tea before that. My rear molars were preparing to do the backstroke.

Once the bladders are quite full, the ureters can no longer disgorge urine; backpressure builds up into the kidneys.

The kidneys’ reaction is to slow, and eventually cease removing fluids and toxins from the blood stream.

When toxins are no longer removed, the muscles grow weak, the eyes grow bleary and the brain’s processes are less than optimal.

How much fluid in my bladder now? Well, I recalled that once after a surgery, under narcotics for pain control, my urinary system stopped. Completely. Finally, after what seemed forever, I suddenly spewed forth nearly one full liter. [Nurses are compelled to measure such things.]

I got the (obvious) idea to use the now empty water bottle as a receptacle. Could I manage?

I began studying the woman in the large Chevy Yukon beside me. Would she notice if I did my own great “Southern Exposure”? Perhaps not, if I timed it correctly.

This would be my own exercise in damn good flow control… I had no interest in spillage. A further challenge to flow control: once the dam’s gateway was open, how would it stop at the bottle’s ¾ liter capacity when as much as a liter could be required?

At this level of desperation there is only one method of flow control: damn good will-power.

I have a bit of a sensitive nose, and so I’ve been known to sneeze … suddenly and violently. As the barn door opened and the plumbing interfaces successfully engaged for a tight connection … I got the tickle. The nose tickle.

Focus Joe. Focus. If you feel a sneeze coming on, sometimes you can avoid or postpone it by breathing slowly through the mouth, with no air flow over the sensitive nasal hairs.

During this important meditation … focus, focus, stay engaged, breath gently, through the mouth … two things suddenly happened that startled me. One: the lady to my right got curious and glanced into my car. Oh my! The shame! Did she see Little Joe? Two: the car in front of me began to inch forward. Through all of my focus and will power I had failed to notice that far ahead the cars had begun to crawl. The inch-worm wiggle had made its way to me.

Engaged in will-power and mind control – engaged in a tight plumbing connection – I allowed my car to move perhaps one car length. Whereupon the line stopped. Five seconds later it started again … for one more car length. This repeated itself again, and again.

This was going to be “difficult.” I’d say “hard”, but “difficult” is more appropriate. Inching along, with Mrs Kravits (of I Dream of Jeanie, oops, Bewitched [7]) sneaking peaks, the morning glory spillway began to flow.

First a trickle, and then a full throttled torrent cascaded into the previously empty Dysani bottle. The good old ’99 Acura inching along, Gladys Kravits almost hitting the car in front of her … the fluidic seal miraculously held tight and there was no spillage.

Gladys Kravitz, the nosy neighbor. [8]

Gladys Kravitz, the nosy neighbor. [8]

I became aware of the rate the bottle filled by its new warmth. Urine emerges at the full 98.6 degrees Fahrenheit of the body.

One final challenge remained. Enjoying this full and sensational release,… I wondered how my will power – my flow control – how Little Joe would perform in the task of stopping at ¾ liter when there would be so much pleasure to be had in going the distance? So much pleasure in unloading the last full measure of … bodily fluid.

Somehow I managed everything. Keeping a steady distance between cars in stop-and-go traffic. A tight fluid seal. Stopping at 100% bottle volume, with a little something left in my tank … so to speak. Getting the cap neatly back on the bottle. Little Joe back home where he belongs. Good material for nosey Mrs Kravits to have future gossip sessions … or sweet dreams.

Just as mission was accomplished traffic started moving steady. First 1 mph. Then 10mph. Then 15. Then 30. In a few minutes I was passing the mudslide on a single inside lane that had been cleared.

What a mess the road was. But my car, bottle, pants and car seat were not a mess. Whew.

As soon as traffic opened up a bit, and access to the right shoulder opened up too, I spied about 20 cars pulled over with gentlemen who were facing away from the highway.

I couldn’t hold it quite as long as they did. But my flow control was still damn good.


Wishing you safe travels and clean flow.

Joe Girard © 2015



[1] The westbound tunnel is the Eisenhower. Officially the eastbound tunnel is the Johnson Tunnel, although usually both are referred to as “Eisenhower.”

[2] Dillon Reservoir is often referred to as Lake Dillon, or Dillon Lake.

[3] http://www.eia.gov/tools/faqs/faq.cfm?id=97&t=3

Average household consumes 911 kWh/month divided by 24hrs/day and divided by 30.4 days/month = average burn rate of 1.2kW.

1.8×106W divided by 1.2×103 W = 1,500

I also estimate this takes only ~260ft3/sec, or 15,600 cfm.

[4] Recent work at the dam:



[5] The Morning Glory Spillway was also upgraded during the recent work at the dam

[6] Roberts tunnel and Denver water supply. http://summitcountyvoice.com/2012/09/02/colorado-roberts-tunnel-turns-50-this-year/

[7] oops, I got confused between two magical women shows from the ’60s, and the nosy neighbor lady.  Thanks to Gil G for catching this boo-boo.

[8] The role of Gladys Kravitz was played by Alice Pearce, from 1964-66, when she passed away, aged only 48.  She was awarded an Emmy for her portrayal posthumously. She was known as “the chinless wonder.” Sandra Gould took over the role until filming ended, in 1971. Pearce and Gould were good friends. Resource==>  Gould gets role of Mrs Kravitz

I might have this confused a bit with the role of Amanda Bellows (married to NASA doctor, Dr. Bellows) from I Dream of Jeannie, played by Emmaline Henry.  Ms. Henry also died rather young, on 50 years old.