Diablo Lake & Lunch Tour: Dams, Monkeys, and a Green Lake

Diablo Lake isn’t a lake. It’s a five-mile reservoir created by Diablo Dam. Tucked within the North Cascades in Washington State, it has a stunning setting with snow-capped mountains on either side. Even more remarkable is the lake’s green hue, which is from particles of mica in the glacial rock flour (a dust mixture from glaciers grinding against rocks).

Diablo Lake lookout on HWY 20 in Washington State.

The most popular spot to see the lake is at the overlook along HWY 20. Over the years, I’ve stopped here many times, and it has never ceased to amaze. What you might not be aware of is another way to see the lake – the Diablo Lake & Lunch Tour by Seattle City Light’s Skagit Tours. This tour not only gets you down on the lake in a boat, but you get to see Diablo Dam and Ross Dam up close, learn facts about the dam and its history, tour Ross Dam (this only happens when an operator is available), and a enjoy a fabulous lunch back at the North Cascades Environmental Learning Center.

Last year, Seattle City Lights invited me to experience the Powerhouse Insiders Tour, which takes you inside the Gorge Powerhouse and you can read about  it here. (If you love history and dams, I highly recommend this very affordable tour.) This year, they invited me back to experience the Diablo Lake & Lunch Tour. In July, my sister, cousin, and I drove to the North Cascades to experience Diablo Lake via boat tour. By the end of the tour, all three of us came away with a greater appreciation of the lake,  the dams, and the power they produce.

Diablo Lake & Lunch Tour

The Diablo Lake & Lunch Tour runs from the end of the June to the  end of September and check-in begins at 10:15 am (you can see the days here). The cost is $42 for an adult, $40 for a senior, and $21 for children 3-12. They also have an afternoon cruise, that does not include a meal and is $12 less for adult and senior tickets, and $6 less for the child ticket. Visit their website to book a tour.

Diablo Lake in the North Cascades in Washington State.

Diablo Lake & Lunch Tour: Dams, Monkeys, and a Green Lake

Diablo Lake & Lunch Tour Check-in and Orientation

Check-in is at 10:15 am and takes place at the North Cascades Environmental Learning Center. To get there, you must drive over Diablo Dam. Yes, you drive over it! If you arrive early, I suggest parking your car in the gravel area on the other side of the dam and taking a short walk out onto the road and snapping a few photos. Guests check-in outside the cafeteria and if you are in need of a little sustenance there is coffee, tea, granola bars and apples in the cafeteria. There is also a bathroom. When everyone arrives, there is a brief orientation. Afterward, you have the opportunity to walk to the boathouse or take the bus.

Boat tour guests check in at the North Cascades Environmental Learning Center.

Before I get too far into the tour, I should say that the day of our tour, the clouds had taken over the sky and as we drove closer to the park it began to rain. This had me worried, and I hoped that the clouds would lift and the rain would stop. Thankfully, that is what happened.

Sourdough Creek

We had two main tour guides, Bonnie and Kara. We opted to walk to the boathouse with Bonnie, while Kara drove the bus. Along the way, Bonnie stopped at Sourdough Creek. She asked if we noticed anything unusual about the road over the creek. As you can see, the road is in sections. Each summer debris would come down the creek and destroy the bridge. Instead of building a new bridge each year, they created a modular bridge. These sections can be removed at any time. When the creek bed fills with debris and sediment, they can scoop it out and put the bridge in position.

Tour guide at Sourdough Creek, a modular bridge.

Travel tip: In Western Washington, you never know what the weather will bring. We went on our tour at the beginning of July, which for most in the Northern Hemisphere means warm weather. As you can see we are in jackets, long pants, and hats.

Sourdough Creek is fed by a glacier on top of Sourdough Mountain.


Seattle City Light Diablo Lake Tour

Next stop, the boathouse. Once the guides are given the go-ahead, everyone boards the Alice Ross IV.The boathouse for the Diablo Lake & Lunch Tour.

This boat was designed for the tours. It is roomy with seating on both sides, heating/air conditioning, a large bathroom, and a 14-foot deck in the back. It also has lots of windows to take in the view, including windows on the ceiling! 
Glass ceilings on the Alice Ross IV for the Diablo Lake & Lunch Tour.

While at the boathouse there is another brief orientation about the boat and how to move around. The main thing to keep in mind is to have three points of contact when walking around the boat (two feet and one hand), and if you go onto the back deck, to be aware of your camera, phone, and footing. In July, the water is around 46 degrees, and that is not something you want to fall into. 
Orientation on the boat during the Diablo Lake & Lunch Tour.

Diablo Dam

J.D. Ross is the creator of the dams (Gorge, Diablo, and Ross). He built them with the intent to provide electricity to the city of Seattle. Today, the dams provide 20% electrical power to the Emerald City.

The first dam, Gorge Dam, was built in the 1920s. The second Diablo Dam, which is a concrete arch dam took two years to build and was completed in 1929. At the time the 389-foot dam was the largest dam in the world and cost around four million dollars to build.

In 1936, it started providing hydropower. It has 19 spill gates; three can be opened remotely in Seattle, and the remaining 16 need to be opened by hand. Its generator capacity is 153 MegaWatts.


Fun fact: When Diablo Dam was built, it was the tallest dam in the world.

Hydropower Tours

A couple of years later, J.D. Ross started boat tours on Diablo Lake (he had already been doing tours at the Gorge Powerhouse). The tour turned into a two-day event, partly because the journey to get to Newhalem included travel by train, and once in Newhalem, you had to get from there up to Diablo Dam.

A unique part of the tour includes stops in front of two islands that used to house wild animals. What were they? Monkeys and white Asiatic deer. One island had the monkeys and the other the deer, hence the names Monkey and Deer Island. J.D. Ross hired a gamekeeper to take care of the animals, and each night they were brought into a safe location and each day brought out to the islands.

Monkey and Deer Island in Diablo Lake.

Even though they were taken care of, not all of them fared well over the years. First, the weather is colder than their home climates, and some perished. Others were lost to cougars who swam over to the island to find dinner. Some of the white deer swam to shore and mated with local deers. If you see blonde colored deers during your visit, they are the descendants of those white deer.

Descendants of white deer at Diablo Lake in Washington State.


Fun fact: Seattle City Light has been running boat tours for over 90 years!

The Canyon to Ross Dam

The boat wanders around the lake, giving you plenty of opportunities to take photos, ask questions and enjoy the scenery. Then the boat enters a slender canyon that ends at Ross Dam.


Along the way, the guides talk about salmon, the rocks that give the lake its color, and the partnerships that Seattle City Light has with places like the learning center and Canada.

Stopping at Ross Dam

At Ross Dam, everyone gets out of the boat (belongings such as purses and backpacks stay on the boat. Cameras and phones can come with you). Here, you’ll find out if you get to go inside Ross Dam, which only happens if a powerhouse operator is available. They will take you inside (with hardhats and earplugs) and explain what the machines are doing and answer questions. Both options include the guides giving an overview of how the dam generates power.

Information on how dams work.

I have to admit, I’m not a technical person, and some of the details are lost on me. If I understand it correctly, water moves through blades at high speed which turns the turbine to generate power.

One of the highlights of being lead by the operator is getting to see the powerhouse room and touching the generator shaft!


One of the drawbacks is that it is quite loud. If you want to hear everything the operator says, be sure to stay to the front.

The tour ends with a great view of Ross Dam, which is also a concrete arch dam and created a reservoir that is called Ross Lake. Construction was completed in 1949, and the dam went online in 1952. Its generator capacity is 339 MegaWatts.

The dam has a waffle pattern, which allowed for more surface to bond with the structure. The outside layer was not needed and never put on.

Ross Dam in the North Cascades National Park.

Back on the boat, you’ll also get another chance to view the dam and outside of the powerhouse.

Ross Dam in the North Cascades National Park.

The guides make sure the tour stays on track to get everyone back for lunch. This part of the ride is the perfect opportunity to ask questions, and take photos.Seattle City Lights Diablo Lake Tour.

Lunch at the Environmental Learning Center

Back at the center, lunch is served buffet style, and I was surprised at the freshness and creativity of the meal. There was a salad bar, two soup choices, two main course choices, and bread. If you requested gluten-free or vegetarian, the guides found you to let you know which items were for you.

I opted for a salad, salmon chowder, and shepherd’s pie. The shepherd’s pie was the best I’ve ever had, and I went back for seconds. Cookies (including gluten-free)were put out for dessert.

During lunch, the Chef Justin came out to chat with the group. He explained that they source their foods within 125 miles east and west of the center, which includes hot and cold weather crops, dairy, and meat. Anything not sourced within that range is organic, and they strive to have “the best food quality they can.” I have to say, from the lunch they prepared for us, it showed.

On the Diablo Lake Tour in North Cascade National Park.

Final Thoughts

We all enjoyed the tour, and if you are into history and hydropower, I would recommend it. Along with seeing the dams, learning about their history and going inside the powerhouse, you also get to be out on the lake which you might not get to experience unless you have a boat or kayak. The only thing I would quibble about is that since it was the very first week of the tour, one of the guides did not know some of the material that well. But, she won me over with her personality and did go out of her way to answer my questions. Budget wise, the price is affordable at $42 for an adult ticket, especially when you factor in a fabulous lunch. And, if you want to save even more money, the option for the afternoon tour at $30 for an adult ticket without lunch is even more budget-friendly.

Seattle City Lights Skagit Tours offer three tours:

  • Powerhouse Insiders Tour (includes lunch)
  • Diablo Lake & Lunch Tour and the Diablo Lake Afternoon Cruise
  • Dam Good Chicken Dinner & Ladder Creek Falls by Night

If you want to make a day of it, consider the Powerhouse Insiders Tour followed by the Diablo Lake Afternoon Cruise and the Dam Good Chicken Dinner.

Tours start at the end of June or beginning of July and end within the first two weeks of September (some dates vary by tour). Visit their website to book a tour.

What To Do After Your Diablo Lake & Lunch Tour

The tour ends around 2 pm (depends on how long you take to eat lunch). If you want to extend your time in the North Cascades you can:

  • Stretch your legs on the short trail next to the cafeteria
  • Drive to the Diablo Lake lookout on HWY 20
  • Hike in the North Cascades
  • Drive east to the Gorge Overlook and walk the interpretive trail
    • Go on a self-guided Newhalem walking tour
    • Visit J.D. Ross’s crypt in Newhalem
    • Stop in the Skagit General Store in Newhalem
  • Drive west to the Old West town of Winthrop or Twisp
    • On your way, stop at the Washington Pass overlook

Nearby Lodging Options

From my home base in Anacortes, getting to the center is around a two-hour drive. If you are coming from Seattle area, it will, of course, be a longer drive. If you want to shorten your drive time, there are some lodging options. Camping in North Cascades National Park will put you the closest to the lake and drive time could be anywhere from 10 minutes to 30 minutes depending on where you camp.

In Marblemount, which is the closest town and around a 40-minute drive, is Glacier Peak Resort & Eatery. If you prefer brand hotels you’ll find an assortment in Burlington and Mount Vernon, which is around a 1.30-hour drive. If you are driving from the west side, the Old West town of Winthrop is 1.20-hour drive. There are quite a bit of lodging options here. I can personally recommend Pine Near R.V. Park for camping and cabins and River Run Inn (I’ll be writing about this soon).

No matter where you choose to stay, give yourself plenty of time and take into consideration that once you get into the park the roads become curvy.

Note: As is common in the travel industry, the writer was provided with a tour for the purpose of review. While it has not influenced this review, the writer believes in full disclosure of all potential conflicts of interest.

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Diablo Lake in the North Cascades.

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22 thoughts on “Diablo Lake & Lunch Tour: Dams, Monkeys, and a Green Lake”

  1. This tour looks like so much fun. I really like the short video clips you placed within the post. The footage was really pretty and your panning was very smooth. The sound of the water is so relaxing! And good to know that Diablo Lake isn’t a lake 🙂

    • Candy, Glad you enjoyed the post and the mixed in video. I’m more of a photo person, but I think the video gives a nice visual break from the text. Thanks so much for commenting!

  2. What a fascinating tour! I must admit when I read monkey in the title I thought I had slept in a biology lessons thinking gosh I had no idea there were monkeys in the states! Also, I love the fact there are blond deer descendants. The lake, which is not a lake, looks stunning surrounded by those mountains.

    • Anna, The lake is quite something. That color mesmerizes. After learning about the white deer and their descendants, it was so cool to see one. Walked right by the cafeteria during lunch.

  3. The Diablo Lake and Lunch Tour is definitely something our family would enjoy. It has everything each member of our family would enjoy. Our daughter would love being on the lake, our son would love learning about the animals, my wife would love to learn about the engineering of the dams, and I would enjoy learning about the history of the construction. The lunch looks fantastic, and I like that the food is locally sourced. I like that you get to see a little bit of snow in July while touring on the exquisite reservoir.

    • Lance, There were several kids on our tour, and one young man was really into the rock aspect. He explained to us all about glacial flour. Another was super excited Ross dam sounded very similar to his name. Both seemed to really enjoy themselves throughout the tour. It sounds like this tour really touches all the bases for your family and would make everyone happy. I hope you get to experience it soon!

  4. That tour looks super interesting and the colour of the water is insane! I liked the information about the monkeys and deer as I was a little confused about it when you mentioned the monkeys. The blonde deer sound very cool, but such a shame that cougars depleted the population of white deer. Very interesting post, I would love to visit one day.

    • Amber, Thanks so much for commenting. I loved learning the story about the monkeys and deer. Such a strange thing to have there, but I’m sure many people came because they wanted to see them.

  5. That water is such a beautiful colour! I think we’d probably make a day of it and end the day with the Damn good chicken. It’s certainly a unique way to explore an area

    • Leah, I think it is great how they’ve scheduled the tours so you can piggyback on previous tours to really dig into discovering the area. Thanks so much for commenting!

  6. Hello Lara!
    Thanks for sharing this awesome tour with us! The white deer looks so beautiful – it must had been a great expirience! Hopefully I can go there one day – really wonderful article!
    Have a wonderful day,

    • Martina, It was really neat to see the deer after learning about them on the tour. I hope your travels take you to Washington State soon!

  7. I’ve never heard of this place before but it looks incredible, it reminds me of a lake created by a dam over in Albania! It seems like such an interesting but also stunning place to visit with the views and the info about the dam itself.

    • Nicola, I haven’t been to Albania yet, but if parts look like the North Cascades I’m there!

  8. Fascinating tour! I didn’t realize these dams were built so long ago — they’re nearly 100 years old! I would very much like to take this tour, and I’m pleasantly surprised by how reasonable the prices are. So smart of them to start these tours early in their history. I’m sure a lot of people have been enriched by taking them.

  9. I went to Washington a couple years ago but only visited the Seattle. I’m dying to go back and see more nature and out of the big city areas. Diablo Lake (or Dam) is beautiful! I love how green the water looks. It actually reminded me of pictures I’ve seen of Alaska. 🙂 Glad you enjoyed your trip there.

    • Edith, Ah, Alaska. Lived there for ten years, loved it. You won’t be disappointed by the lake or the North Cascades. Such a pretty area and the drive is one of my favorites. Next time you come back, explore outside of Seattle!

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