Thursday, October 5, 2017

New Fish Screens at Fish Passage

Last week several members of our Fish Passage project took a trip to Sacramento to examine the project’s fish screens designed by Intake Screen Inc. (ISI). Next week, our team will be installing four of these fish screens at Fish Passage Facilities located in Alameda Creek.

Pictured below is one of the four new fish screens.

Here is Yen Ng, one of our project engineer’s; looking through what is called an internal cylinder brush. The internal cylinder brush is a key component of the fish screen.

Below is a diagram of a fish screen and its significant components.

Image courtesy of

The goal of the Fish Passage Project is to provide for safe passage of fish around the Alameda Creek Diversion Dam to support the restoration of Steelhead trout to the Alameda Creek Watershed. The project is part of the San Francisco Public Utilities Commission’s $4.8 billion Water System Improvement Project (WSIP) to repair, and seismically upgrade portion of the Hetch Hetchy Regional Water System.

Construction is expected to be completed in fall 2018.

See you around the valley!

Friday, September 22, 2017

Photo Friday at the Arroyo Hondo

Happy Photo Friday!

Today's post comes courtesy of watershed keeper Pat Jones.

Recently cloudy skies helped produce some stunning photos. This one shows Calaveras Reservoir and a major tributary into it - the Arroyo Hondo.

Have a great weekend, and we'll see you around the Valley!

Friday, September 15, 2017

Meet Sunol Valley's Natural Garbage Collectors

This week we wanted to highlight some special local inhabitants - turkey vultures.  If you drive anywhere in the Sunol Valley, you will almost always spot a committee of vultures waiting to see what their next meal will be. 

Turkey vultures, like this one spotted near Calaveras Reservoir, like to roost in bare trees to keep an eye (and nose) out for their next meal.

Turkey vultures, also known as turkey buzzards, are the most widespread species of vulture in the New World. They are so named because of their resemblance to the male wild turkey. Their range spreads from Canada all the way to the southernmost tip of South America. We call them nature’s garbage collectors because they feed almost exclusively on carrion and perform a crucial natural function of picking clean disease carrying carcasses.

Vultures are probably one of the most misunderstood birds in the animal kingdom. Here are some fun facts about these creatures:

  • Turkey vultures have one of the best senses of smell in the animal kingdom.
  • It's a misconception that they actually prefer their food rotten.  However, vultures do have a cool adaptation; their stomach acid is almost comparable to battery acid.
  • Nothing goes to waste with a vulture. They even make good use of semi-digested and digested food.

Photo courtesy of WikiCommons

Although few people would call them cute, they do perform a crucial role in natural areas like the Sunol Valley. 

See you around the valley!

Friday, September 8, 2017

The Building Blocks of the Replacement Calaveras Dam

If you are new to the world of dam construction, you might wonder what types of materials are used in building one.  Today’s blog will focus on what types of materials we are using to construct the new Calaveras Dam. Calaveras Dam is an earth embankment dam.  Earth embankment dams tend to be constructed of all types of geologic materials.

Calaveras Dam, July 2017
The picture above was taken recently; from it you can visually see the different materials. Let’s start with the middle and the most important material used in our dam, the core. 

The Core of Calaveras Dam

Zone 1 & 1A—aka…the Core
The core is made up of clay.  Clay is very dense and less permeable than most materials.  Our new dam will have a large core, which will help ensure that the dam withstands a 7.2 magnitude earthquake.  The clay used in our dam has been ‘borrowed’ from the south end of Calaveras Reservoir.

The core is taking shape.

Zone 1A- Core’s foundation
At the bottom of the core, you will find Zone 1A material. This clay is plastic, pliable clay, or another words, clay that has a Play-dohtm like consistency.   Zone 1A material is placed on the foundation’s bedrock and acts as a seal against water flow beneath the dam.

The core is the most important element of the dam and therefore must be protected.  We protect our core by using filters in both the upstream (reservoir side) and the downstream (dry side) of the dam to control the seepage of water and remove it safely from the Dam.

Zone 2 and 2A- Sand
Upstream zones are made of sand  (Zone 2A) and large gravel (Zone 5A)The downstream filters or chimneys are made of sand (Zone 2) and pea gravel (Zone 3).

Zone 5-Rock Fill
Further protection for both the core and filters is provided by rockfill shells. The upstream shell consists of hard durable rock because it will be submerged in the reservoir, Zone 5 material.  This material consists of metamorphic rock known as blue schist.

The downstream shell (Zone 4) consists of onsite material from a geologic formation known as Temblor Sandstone.  While this is a sedimentary rock, it tends to degrade into a gravelly, sandy soil and is best suited for drier conditions than the upstream shell.

Zone 6- Rip Rap
Wave action in the reservoir due to wind can erode most earthen materials.  Large durable rocks are placed on the slopes of the dam at the waterline to prevent this erosion. This is Zone 6 also known as rip rap.

Image courtesy of

See you around the valley!

Friday, September 1, 2017

What is a desmostylus and what is it doing in the Sunol Valley?

Photo courtesy of

A Desmostylus was a hippo-like creature that lived about 20 million years ago. It happens to be the only order of marine mammal to have gone extinct. Some individuals lived along the shoreline of an ancient ocean that used to be located where the Sunol Valley is today.

If you stumbled upon this would you know it was a rib cage?  What it looked like prior to Excavation

During excavation of the Calaveras Dam Replacement Project, the project paleontologists found not only a few teeth belonging to these strange creatures, but recently found an entire rib cage. Removing the fossilized rib cage of an animal that likely weighed between 200 and 400 pounds in life is no small task.

First the bone had to be cleaned and separated as much as possible from the surrounding rock on the hillside.

Above is the picture after our fossil was cleaned and ready to be removed.

In order to physically remove it from the hillside, crews used a lift to grab the entire rib cage. Now that the rib cage has been safely removed from the construction site, it awaits further stabilization treatment by project paleontologists. 

See you around the Valley!

Friday, August 18, 2017

Photo Friday in Sunol Valley

This week we wanted to share a snapshot of construction underway at the Fish Passage Facilities in the Alameda Creek Watershed located adjacent to the East Bay Regional Park District's Sunol Regional Wilderness.

The photo below shows the construction of the intake structure were the fish screens are being constructed.  This particular intake structure will have a total of 4 fish screens (high tech contraptions that will prevent fish from being drawn into the intake structure).

The goal of the project is to provide for safe passage of fish around the Alameda Creek Diversion Dam to support the restoration of Steelhead trout to the Alameda Creek Watershed. 

This project is part of the San Francisco Public Utilities Commission's $4.8 billion Water System Improvement Program to repair, replace, and seismically upgrade portion of the Hetch Hetchy Regional Water System.

Construction is expected to be complete in fall 2018.

Happy Friday! 

Thursday, August 10, 2017

National Water Quality Month

August is National Water Quality Month! Your drinking water comes from a watershed. And if you are a customer of the San Francisco Public Utilities Commission (SFPUC) or one of our 27 wholesale customers in four Bay Area counties, your drinking water comes from three watersheds: the Tuolumne River Watershed near Yosemite National Park, the Alameda Creek Watershed in the East Bay, and the Crystal Springs Watershed on the Peninsula.

By protecting and preserving the lands that produce our drinking water, we not only support rare and endangered wildlife, we also provide the highest possible quality water to our customers.

In honor of National Water Quality month, we’d like to take this opportunity to remind ourselves how we all can help protect our local watersheds to protect the quality of our water.

The SFPUC owns 35,000 acres of watershed lands in the Alameda Creek Watershed. They are home to critters, like the Western Pond Turtle.

As part of National Water Quality month awareness, there are small things that you can do in your everyday life to help keep and protect water quality. Here are some helpful tips:
  • Use a commercial car wash — cleaning your car at home flushes dangerous chemicals down the storm drain and directly into our lakes and streams
  • Pick up after your dog
  • Dispose of used motor oil properly - one quart of motor oil can contaminate more than 250,000 gallons of water
  • Help pick up litter on the streets that could end up going down the storm drain use detergents that are phosphate-free 
  • Join in a beach, stream, or wetlands cleanup project. Look for local projects in your area.
By doing these simple things you will be contributing to protecting your watershed for future generations.

Thank you and Happy National Water Quality Month!

Thursday, July 13, 2017

Northern Rough-winged Swallow Chicks Relocated at Alameda Recapture Creek Project

During the month of June, part of our construction management team at the Alameda Creek Diversion Dam (ACDD) project relocated 5 adorable Northern Rough-winged swallow chicks.  The relocation of the chicks was done by lead biologist, Chris Pattison, with the assistance of another lead biologist, Matthew Bettelheim. Chris Pattison was the only biologist handling the baby chicks. The entire process was performed under a U.S. Fish and Wildlife (USFWS) relocation permit.

Lead biologist, Chris Pattison preparing to relocate the chicks

Rough-winged Swallow Chicks at ACDD Project

They were immediately transported to the Lindsay Wildlife Hospital for a full veterinarian examination.  All of the baby chicks passed their examinations and were then transferred to the Native Songbird Care and Conservation in Sebastopol, California.  Native Songbird Care and Conservation specializes in insectivorous birdsThe chicks were reared until they were ready for release.

Northern Rough-Winged at ACDD project

A plain brown bird, Northern Rough-winged swallows are common across the United States in the summer. They are solitary and are usually seen singly or in a small group.  The bird gets its name “rough-winged” because their outer wings have small hooks or points.

See you around the valley!

Thursday, July 6, 2017

Preventing Fires in and around our Watersheds

Calaveras Reservoir 

Happy belated Fourth of July!

We are in the middle of fire season and it’s good to keep in mind how we can prevent fires in and around our watersheds.  Our watersheds, the San Antonio and Calaveras reservoirs are a critical part of our infrastructure because they provide clean drinking water to millions of people in the Bay Area.  They’re also home to wildlife, fish and livestock. According to the Environmental Protection Agency, more than $450 billion in food, fiber, manufactured goods and tourism depend on clean, healthy watersheds. Today’s blog is a continuation of our summer fire safety series, focusing on preventing fire in and around our watersheds.

Image courtesy of

Fire Triangle

There are 3 key elements that need to be present in order to ignite a wildfire.  Those three elements are humidity, fuel (grasses, sticks, branches etc…) and wind.  Typically, if the humidity in the air is lower than 30%, coupled with fuel and wind, you’re bound to create a fire.  Out of all of the three elements, wind is the most dangerous because it provides oxygen to a fire. Wind not only controls the direction, spread, and size of fire, but also greatly affects the flammability of plants by reducing fuel moisture.

San Antonio Reservoir

Preventing Fires in and around Watersheds

Here are some helpful tips on how to prevent fires in and around our watersheds:
  • Be careful and stay in well established graded/mowed roads
  • If you have an ATV’s- remember just because you have an ATV doesn’t mean you’re safe 
    • Use ATV’s only if weather permits
  • Pay attention to the condition of the fuel around you, especially on hot, windy days
  • Be aware of your vehicle’s exhaust, whether you’re on an ATV, car or any other type of mechanical equipment
    • If you have to pull over to the side of the road, be careful not to park over dry fuel (grasses)
  • Fireworks- careful not to set them off in or around dry fuel (grasses)
  • Shooting Guns- sparks from guns or any other type of firearm can ignite a fire given the right conditions
  • Mowing –is the biggest causes of fires, try not to mow past 10 a.m.
  • No smoking near the watersheds
 If you see a fire near or around a watershed please call 911 immediately!

Additional fire resources:
·       CAL FIRE at:
National Fire Protection Agency,

Friday, June 30, 2017

Building Dams in Earthquake Regions, Part II

As Californians, we live with the possibility of earthquakes.  Here at the Calaveras Dam Replacement Project we are in the middle of constructing a new dam that will be strengthened to resist seismic forces and withstand a 7.25 magnitude earthquake.  Dam technology has evolved since we built the original dam in 1925. 

If you missed our first blog about the technology used in construction of the original dam, see it here. The methods used in constructing the new Replacement Calaveras Dam are very different. Here’s why.

New Construction Methods

We are using state of the art dam technology and engineering to enhance the safety of this large civil structure.

A Sound Foundation

Our director Dan Wade says that building an earth and rock fill dam is a lot like painting a house. You need to strip all the old paint off the walls to get to good wood. You need to prime the surface so it will hold the new paint. The very last thing you do is paint.  We have been doing the preparation for the building of our dam for 6 years. We have moved more than 7 million cubic yards of soil to reach competent rock as a solid foundation of the new dam. 

A cross section of the replacement dam showing the different zones. Green is upstream (the reservoir side), light yellow is downstream, the clay core is in the center, and the narrow yellow strips are the drains and filters.

Controlling Water Seepage

We have drilled the grout curtains (see our previous blog about curtains and blankets) extending more than 100 feet below the dam’s foundation to control water seepage. We have done even more work to treat the foundation of the core of the dam, which is made of impervious clay. Remember the drain blanket? That also is constructed on the downstream face (the dry side away from the reservoir) to control water. The new dam will have various filter zones and drain zones on both sides of the dam to control the movement of water so it does not compromise the structural integrity of the dam.

Resisting Seismic Forces

A wide core will help the new dam be robust. In addition, the materials placed in this dam will be compacted using heavy machinery.

Here's the dam being constructed as it looks now. The different zones are clearly visible.

The complete removal of unstable rock and soil to form a solid foundation, careful design and placement of filters and drains within the dam to control water, extensive grouting and sealing of the foundation of the dam, a robust core and heavy compaction of all materials enable the replacement Calaveras Dam to withstand seismic forces and serve our customers for generations to come.

Monitor our progress at building the dam here at

See you around the Valley! 

Friday, June 23, 2017

Building Dams in Earthquake Regions Part I

The First Two Calaveras Dams

As Californians, we live with the possibility of earthquakes.  Here at the Calaveras Dam Replacement Project, we are constructing a new earth and rock-fill dam that will be strengthened to resist the seismic forces and withstand a 7.25 magnitude earthquake. 

Dam technology has evolved since we completed the original dam in 1925. In a two-part series, we’re going to take a look at how our predecessors built the previous Calaveras Dam, which has served us well for 90 years, and what new technologies and construction methods we are using for the new dam to be ready for the next big quake.

The original Calaveras Dam (construction spanned 1913 to 1918) was constructed using the so-called hydraulic fill method.  Basically, to create the impermeable 'puddle core', fine soils were washed off the surrounding slopes with high pressure water cannons, and this slurry was collected between two 'training' dikes on both sides of the dam’s core.

During gold mining in the Sierra foothills, this method was used to build much smaller dams to impound water for hydraulic mining. But scaling this method up to this size had some serious problems. 

The first Calaveras Dam, nearly complete in 1918. It was the largest earthen dam in the world at the time.

The process did not allow excess water in the puddle core to dissipate, and this extra weight exceeded the ability of the upstream shell to retain it, and it failed as it neared completion.

The second (current) dam was completed in 1925 and was built on the remains of the first dam. For the current dam, soil was compacted in the core, primarily by running heavily-loaded wagons over it (pulled by mules). In this photo you can see the mule trains compacting the core.

The second Calaveras Dam, shown in 1926.

However, one problem that wasn't addressed during the construction of the current dam was the fact that alluvial soils (creek sediments including silt, sand, and gravel) were not removed before the first dam was constructed. Such saturated, loose sediments, which are removed during the construction of a modern dam, have the potential to 'liquefy' as they are shaken during an earthquake. 

It was for this reason that we at the SFPUC elected to build a completely new dam next to the existing dam.  And this time, things were different. 

Stay tuned to learn more!

Friday, June 16, 2017

Bald Eagle Photo Friday at San Antonio Reservoir

Happy Photo Friday!

This week’s pick comes courtesy of Kevin and Pat from our Natural Resources and Lands Management staff.

We have spent a lot of time writing about the nesting pairs of bald eagles who reside at Calaveras Reservoir and the pair near our restoration sites near San Antonio Reservoir in the SFPUC-owned Alameda Creek Watershed. But we’d like to introduce you to a more recent arrival to the San Antonio Reservoir area.   

This pair has made its home closer to our Turner Dam at San Antonio Reservoir.  Since it is the time of year when our pairs are on their nests taking care of chicks, our staff spotted two eaglets in their nest.

Once bald eagles find a nesting location they like, they tend to stay in the area. Which is why these bald eagles and our Natural Resources and Lands Management staff have gotten to know one another.  Our staff monitors the well being of these birds on a weekly basis. They all have been trained on bald eagle monitoring and behavior. Knowing these particular birds and bald eagle behavior enables our Natural Resources staff to know quickly if the birds seem ‘off’ because they have been disturbed by something.  

These little ones will fledge (develop the ability to fly) anywhere from 8 to 14 weeks of age. For now, they’re being fed a consistent diet of fish found in the reservoirs and creeks within the Alameda Watershed.

Healthy watersheds provide high quality water and also provide a safe haven for many amazing plants and animals. We consider it an honor and a privilege to look after these watershed lands, and all who live there, too.

Have a wonderful weekend, everyone!

Thursday, June 8, 2017

Sunol Valley Fire Safety #1

It’s always fire season in California, although it officially begins in May. Our warm and dry climate coupled with climate change has made California more susceptible to frequent wildfires.  According to CAL FIRE, between January 1, 2017 and May 20, 2017 there have been a total of 921 fires in California.

Here at Calaveras dam want to prevent wildfires by our watersheds. During the summer months we will be dedicating a series of fire prevention blogs with tips on how you can help prevent forest fires.

Today we will focus on equipment safety.  Operating equipment like lawn mowers, chainsaws and tractors improperly could ignite a wildfire.  However, according to CALFIRE there are simple steps that you can take to prevent these types of fires.

(Image courtesy of

Equipment Safety Tips:
·       Mow during the cool time of day before 10 a.m. while there is still dew on the ground, not during the day and especially not when the wind is blowing.
·      Remove rocks and metal from the year that could be hit by the mower and cause sparks. 
·       Use a weed eater with a plastic line when cutting dry grass not a lawn mower (use lawn mower on green grass only).
·       Don’t top off fuel tanks.
·       Make sure spark arrestors are in proper working order and there is no carbon build up.
·       When transporting tractors, mowers, and recreational vehicles make sure that chains on the trailers are not hitting the pavement as you are driving.
·       Take special care when using tractors in dry grass that can easily ignite. 
·       Last but not least, always have a least one of the following items with you: fire extinguisher, water supple or a shovel.

Wildfires have an effect on watersheds, reservoirs, and the quality of our drinking water. 
By protecting our watersheds we are protecting our environment. Remember metal
blades hitting rocks can spark a fire!

For more information on wildfires go to:

Friday, May 26, 2017

Blankets and Curtains for Calaveras Dam?

Here at the Calaveras Dam Replacement Project we are building what is called an earth and rock-fill dam. The replacement Calaveras Dam, like all so-called embankment dams, is made of mostly compacted earth (see a cross section of the future dam below). An important aspect of this type of dam is the management of water. All earthen dams leak, the important thing is to control where the water flows to protect the integrity of your dam.  In the case of the Calaveras Dam Replacement project, we accomplish this with blankets and curtains. 

No fooling! Here’s how it works.  For years, the crews onsite have been constructing an entire dam that extends more than 100 feet below the base of the future dam.  We call this a grout curtain. Grout for those of you not in the construction industry is a special mix of cement that can be injected or literally blown onto a surface to seal it.  

Grout Curtains

As you can see in the photo from 2015, crews drilled countless small diameter holes into the bedrock a hundred feet down below the future dam and injected the holes with pressurized grout. The grout effectively seals up cracks and fractures within the rock underneath the new dam.  We did this for years. Why is this grout curtain so important? It prevents water from seeping underneath the new dam and undermining it.  In essence we drilled an entire new dam underneath the future dam. 

Drainage Blanket

If you thought grout curtains alone were enough to protect the future Calaveras Dam, guess again! We need blankets, too. More specifically a drainage blanket. The drainage blanket prevents water from exiting to, and damaging, the down-stream face of the dam (the face of the dam away from the reservoir).  At the end of the drainage blanket we are constructing a ‘mini dam’ made out of the same clay material as the core to capture any water in the drainage blanket. You can see the drainage blanket being constructed here.  This ‘mini dam’ is also known as the seepage barrier.  This seepage water is then collected in an inspection well to monitor the condition of the dam.

The Calaveras Dam Replacement Project, along with its blankets and curtains, is more than 80% complete.

See you around the Valley!

Friday, May 19, 2017

Photo Friday at the Calaveras Dam Replacement Project

Did you ever look at a photo of yourself or a family member from a long time ago and compare it to a recent picture? For today’s Photo Friday, we decided to do just that for the Calaveras Dam and its replacement.

Calaveras Dam in 2011. The project groundbreaking was in 2011. 

Calaveras Dam in April 2017. The project is more than 80% complete. We have moved more than 8 million cubic yards of rock and soil to date. We have fully excavated and grouted the left and right abutments. And in the center of the picture, the core of the new Calaveras Dam begins to take shape.  The huge concrete spillway (as wide as a freeway) is visible at the lower right. Wow.

Construction on this project started in 2011 and is expected to be complete in April 2019.

To learn more about this project and see a time lapse video of all of this excavation, visit us here.  

See you around the Valley!

Friday, May 12, 2017

Photo Friday for the Birds

While this author spent time in the Sunol Valley this week, she spied an amazing bird. 

Sitting atop the construction fencing that keeps small (crawling) critters out of the construction site, was a bird with flaming yellow plumage accented with black.

This striking fellow (and yes it is a male, the females are much more subdued in color) is a Bullock's orioleThe Alameda Watershed is home from spring through summer to Bullock’s orioles, like this first-year male. They'll winter in Mexico or Central America before migrating north again next spring.

They dine on insects, fruit, and raid the occasional humming bird feeder for the nectar. 

See you around the Valley!

Thursday, May 4, 2017

Honoring Construction Safety Week in the Sunol Valley

With so much heavy construction work underway in the Sunol Valley, it is easy to forget that the men and women in the construction industry perform dangerous work often in difficult conditions to upgrade the Hetch Hetchy Regional Water System.

It is a good thing that the construction teams working on the two projects in full swing in the Sunol Valley keep safety in mind every single day.  However, this week was a little different. The teams at the Calaveras Dam Replacement Project and the Fish Passage Facilities within the Alameda Creek Watershed underwent additional trainings and reminders this week.


The first week of May is National Construction Safety Week.  Global construction industry leaders, including our contractors, joined together to form industry safety forums and an initiative called ‘Safety Week.’ The mission of Safety week is to raise awareness within the construction industry ensuring “We are Stronger and Safer Together.”

How strong?

Here in the Sunol Valley, the number of recordable workplace incidents is well below the industry average. At our Fish Passage Project, workers have clocked in over 70,000 work hours since April 2016 with zero recordable incidents.  At the Calaveras Dam Project, the largest project in the Water System Improvement Program has worked over 220,000 work hours since July 2016 with zero recordable incidents. 

Working in heat and rain, on large earth-moving equipment or in tight spaces next to a creek, our crews are showing that every week is safety week.

We are proud of our teams out in Sunol Valley! Stay safe out there.

Crews overseeing operations at the future Fish Passage Facilities

Center of photo shows construction crews at Calaveras Dam placing
Clay Core materials in the replacement dam at elevation 567 ft 

Friday, April 28, 2017

Butterflies, Gates and Sleeves, Oh, My!

What do butterflies, gates, cones, balls, and sleeves have in common?

They are all types of valves used to control the flow of water through pipelines.  Instead of our usual Photo Friday, we thought we’d take the time to honor this under- appreciated, but extremely important, feature in our water system.  For the record, a valve is a mechanical device that blocks a pipe either partially or completely to change the amount of fluid that passes through it. And we at the SFPUC couldn’t operate much in the Hetch Hetchy Regional Water System without them.

Here at the Calaveras Dam Replacement Project, we are installing all sorts of  valves to control the flow of water from Calaveras Reservoir for different purposes. Each valve is specially designed to control water in a specific way without damage to the surrounding pipeline. So, let’s geek out about valves!

ButterflyA butterfly valve is a disk that sits in the middle of a pipe and swivels sideways (to admit fluid) or upright (to block the flow completely). It can also open partially to carefully calibrate the amount of water flowing through the pipe.

We are using a 48-inch diameter butterfly valve to control the flow of water to a temporary supply line for the Sunol Water Treatment Plant.

The Sleeve. The Bailey valve sleeve valve reduces water pressure and controls flow by diverting the water through multiple holes located within the sleeve and discharging to the atmosphere or a body of water. The valve controls flow by sliding one pipe called the gate over another pipe called the sleeve.

One of the Bailey sleeve valves installed in the building that will provide a steady stream of water to Calaveras Creek.

The Ball. In a ball valve, a hollowed-out sphere (the ball) sits tightly inside a pipe, completely blocking the fluid flow. When you turn the handle, it makes the ball swivel through ninety degrees, allowing the fluid to flow through the middle of it.  

These serve a similar purpose as the butterfly valve to calibrate the amount of flow.

The Cone. The body of the fixed cone valve is a tube with a cone in the end welded with some grooves.  Another tube acts as the closure member. This slides over the body groves in a linear movement to regulate until making contact against the seat of the cone when the valve is fully closed. 

This valve is not unlike your bathroom faucet, only in our case, a whole lot larger.

The fixed cone valve is used to discharge water at high pressure from reservoirs or full pipes into the atmosphere.  The flow towards the exit of the valve is not converging so that the discharge is in the shape of a hollow jet. 

The fixed cone valve at Calaveras Dam in operation January 2017.

The Gate. Gate valves open and close pipes by lowering metal gates across them. Most valves of this kind are designed to be either fully open or fully closed. Meaning, unlike the butterfly or ball valves, gate valves tend not to provide controlled flows of water, but either turn the flow completely on or completely off.

Two of the gate valves installed in the water supply discharge line from Calaveras Reservoir.

See you around the Valley!