Mountain Lakes 100 Course Guide

The rolling lake country and the PCT

There is no single defining climb here the way there is at a steep mountain hundred. Instead you get five-ish bigger climbs, a couple in the 1,500 to 2,000 foot range, woven into a lot of smaller 500 to 1,000 foot rollers, mostly on classic Cascade PCT singletrack. It is beautiful and runnable, which is the trap. The grades let you run almost everything, so it is easy to spend too much in the first 30 or 40 miles when you feel great and the lakes are gorgeous.

Run the early loop and the out-and-back at a pace that feels almost too easy. The whole strategy at Mountain Lakes is to arrive at the back half with your legs and your stomach intact, because the course does not blow you up, but a full day of moving will if you let the early miles feel free.

Rocky footing, especially after dark

The PCT here is gorgeous, but it is rocky and rooty in long stretches, the kind of chunky Cascade trail that demands attention every step. In daylight on fresh legs that is fun. At 2 in the morning, 70 miles in, with tired feet and a dimming headlamp, that same rock garden gets slow and sketchy, and it is where people roll ankles and lose big chunks of time.

Train on technical trail, and train on it tired and in the dark. Get your night-running setup dialed: a bright headlamp, real backup light and batteries, and the practiced patience to keep moving cleanly over rock when your brain wants to check out. Quick, careful feet late at night are worth more here than raw fitness.

The night, the lows, and the back half

You will run something like 12 hours in the dark at Mountain Lakes, and the night is the real event of any 100. Plan for the predictable low somewhere in the 60 to 85 mile range, when it is cold and dark, your stomach is over it, and the math of how far is left starts to feel heavy. That stretch is normal. Knowing it is coming, and having a plan to eat, layer up, and keep walking through it, is most of what gets people to the finish.

Because the course is a lollipop, you retrace ground you covered earlier, which is a gift on a 100: you already know the trail, the crew points, and roughly how the closing miles feel. The final loop and the run back to Olallie Lake are runnable for anyone who paced the front honestly. The people who walk it in are usually the ones who treated the easy early miles like they were free.

Aid, crew, pacers, and drop bags

Mountain Lakes is known for strong, well-stocked aid, with around 16 aid stations and a maximum of roughly 10 miles between them, so you are never carrying a huge load between stops. Crew access is limited to a handful of points (places like Powerline, Olallie Lake, Olallie Meadows, the Clackamas ranger station, and Timothy Lake), so plan your drop bags for the stations your crew cannot reach.

Pacers are typically allowed from later in the race (commonly around mile 55 or 70, with earlier access for older runners), which means a pacer can join you for the night and the back half when you need them most. Confirm the current aid-station list, crew points, and pacer rules in the race-day details, then build your crew and drop-bag plan around them.

Hold the early miles back on purpose

The gentle grades make almost the whole front half feel runnable, which is exactly why people overcook it. Pick an effort that feels frustratingly easy through the first loop and the out-and-back, and hike the bigger climbs early even when you do not feel like you need to. Use a grade-adjusted pace to set honest targets for the rolling climbs and descents so you are running by effort, not by your flat splits, and you will not arrive at the night already cooked.

Build a finish prediction against the 30 hour clock

Do not guess your Mountain Lakes finish off a road time. The rocky footing, the night, and a full day of rolling vert all add real time, and a vert-aware finish prediction that accounts for this course gives you a realistic window. Work that window back into the aid-station closing times so you actually know your buffer at each stop, especially deep in the night, instead of doing tired math on the trail.

Reality-check the goal before you commit

If this is your first 100, it is easy to set a finish goal that is either way too aggressive or so vague it is useless. Turn a recent race result into an honest Mountain Lakes equivalent so your A and B goals are grounded in your actual fitness, then plan your splits and your crew timing around the realistic one. A good plan for a hundred is mostly about removing surprises.

Carbs: a steady habit you can hold all night

For an effort this long, target roughly 60 to 90 grams of carbohydrate per hour, leaning to the higher end only if your gut is trained for it, and use a glucose-plus-fructose mix so you can actually absorb it. The thing that wrecks fueling in a hundred is not the daytime, it is the night, when your appetite vanishes and a cold stomach takes less. Keep your intake steady and easy to get down, lean on the well-stocked aid stations for real food and warm calories, and practice eating on tired late long runs so the night feels familiar.

Sodium and fluid: tune to you, then carry enough

Cascade September is not desert heat, but you can still warm up in the exposed midday sections, and over 30 hours your cumulative sodium losses add up. Tune your sodium to your own sweat rate rather than a generic number, often somewhere around 300 to 700 milligrams per liter of fluid, and more if you are a salty sweater. With aid at most about 10 miles apart you do not need to haul a ton of fluid, but carry enough to comfortably cover the longest gap, and add a warm layer plan for the night so you are not burning energy just to stay warm. Weigh yourself before and after a long run to find your real sweat rate and build the plan around your own number.