Hidden in plain sight between the suburban sprawl of Federal Way and the industrial hum of Auburn lies Five Mile Lake. Most people drive past it on Military Road South without even blinking. It’s a 38-acre patch of water that feels like a glitch in the matrix of South King County. If you’re looking for the massive, sweeping vistas of Lake Washington or the high-altitude crispness of the Cascades, you’re in the wrong place. But if you want a slice of authentic, gritty, and surprisingly serene Pacific Northwest life, this is it.
Five Mile Lake Washington is weird. It’s an "urban lake," which is often code for "don't look too closely at the water quality after a rainstorm." Yet, it remains one of the most popular fishing and family spots in the region.
The Reality of Five Mile Lake Washington Water Quality
Let's get the elephant out of the room first. King County monitors this lake closely. Why? Because it’s shallow. The average depth is only about 20 feet, with the deepest pocket hitting maybe 28 feet if the season has been wet. Shallow water plus suburban runoff equals phosphorus. Lots of it.
You’ve probably seen the signs. "Caution: Toxic Algae." It happens almost every summer. The Washington State Department of Health and King County Public Health frequently flag Five Mile Lake for microcystins—toxins produced by blue-green algae blooms. It’s not a joke. These toxins can kill a dog in hours and give a human a nasty rash or worse if swallowed. Honestly, check the Northwest Toxic Algae database before you even load the car. If the water looks like pea soup, stay out. Simple as that.
But here’s the nuance. When the water is clear, it’s a community lifeline. The lake doesn't have a massive turnover rate because it's fed primarily by groundwater and small inlets. It’s a stagnant beauty. On a crisp October morning, the mist sits so heavy on the surface you’d swear you were in the middle of the Olympics, not five minutes from a Dick’s Drive-In.
Fishing Five Mile Lake: More Than Just Stocked Trout
Anglers love this place. If you grew up in Federal Way or Milton, you probably caught your first fish here. The Washington Department of Fish and Wildlife (WDFW) stocks Five Mile Lake Washington heavily. We're talking thousands of rainbow trout every spring.
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Most people show up with a jar of PowerBait and sit on the edge of the L-shaped dock. They catch their limit and go home. But the regulars know better. They bring small inflatable boats or kayaks.
- Largemouth Bass: They hide in the lily pads on the southern shore. You won't find monsters, but 2-pounders are common.
- Yellow Perch: Schools of them roam the deeper middle sections.
- The "Secret" Crappie: They are there, but they’re finicky. Look for submerged wood near the private docks on the east side.
It's a year-round fishery. Even in the dead of winter, when the sky is that specific shade of Washington grey that makes you want to move to Arizona, you’ll see guys in heavy Carhartts casting lines into the dark water.
Why the Park Structure Works (and Doesn't)
Five Mile Lake Park is managed by King County Parks, not the City of Federal Way. That distinction matters for maintenance budgets. The park covers about 30 acres of land. You’ve got a massive playground that’s basically a magnet for every toddler within a ten-mile radius. There are tennis courts that have seen better days and a baseball field that’s perpetually soggy.
The picnic shelters are the real MVP here. People book these months in advance for Quinceañeras, family reunions, and birthdays. There’s something specifically "Washington" about grilling burgers under a cedar-shingled roof while it drizzles outside.
The beach area is... cozy. It’s not sand. It’s that rough, crushed gravel that hurts your feet. But during a heatwave? Every square inch of that gravel is covered in towels. There are no lifeguards. You’re on your own. The county used to staff it decades ago, but those days are long gone.
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The History Nobody Talks About
Five Mile Lake Washington wasn't always a park. In the early 20th century, this area was dense timber and small-scale farming. The lake got its name because it was roughly five miles from the old town center of Auburn (then known as Slaughter).
There’s a local legend about old logging equipment resting at the bottom of the lake. While it’s true that some debris exists, most of what’s down there is just silt and discarded fishing gear. In the 1920s and 30s, there were small resorts and dance halls around these lakes. People would take the "interurban" rail or old Model Ts out for a weekend of swimming. It was the "wilds" back then. Now, it’s surrounded by fences and $600,000 split-level homes.
The Environmental Pressure Cooker
The lake is part of the Hylebos Creek watershed. Everything that happens in the surrounding neighborhoods—the oil from the roads, the fertilizer from the lawns—ends up here. This is the struggle of Five Mile Lake Washington. It is a biological filter for the suburbs.
Volunteers with the King County Lake Stewardship Program take samples regularly. They look at transparency (Secchi depth), chlorophyll, and temperature. The data shows a lake that is "eutrophic," meaning it's highly productive but also aging fast due to human impact. It’s a delicate balance. If we want our kids to swim here in 20 years, we have to stop over-fertilizing the lawns in the 98003 and 98001 zip codes.
Survival Guide for Your Visit
If you're actually going to go, don't just wing it. Parking is a nightmare on weekends. The lot is big, but not "half of King County" big.
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- Arrival Time: If it's over 80 degrees, be there by 9:00 AM. Otherwise, you’ll be circling Military Road like a vulture.
- Geese Management: The Canada Geese think they own the place. They do. Watch where you step. The "goose poop to grass" ratio is often 1:1 near the water.
- Boat Rules: No internal combustion engines. Electric motors only. It keeps the lake quiet, which is a blessing considering the traffic noise from nearby I-5.
- The Trail: There’s a short trail system. It’s not a hike; it’s a stroll. Good for dogs, but keep them on a leash. The brush is thick and there are plenty of blackberry thorns to ruin their day.
Honestly, the best time to visit isn't summer. It's late September. The crowds are gone. The maples around the lake turn a screaming shade of orange. The water is usually still enough to provide a perfect mirror image of the sky. It’s quiet. You can actually hear the birds instead of the "thump-thump" of a car stereo from the parking lot.
Practical Steps for Local Residents
If you live near Five Mile Lake Washington, you have more responsibility than the average visitor. The lake's health literally starts in your driveway.
- Switch to Phosphorus-free fertilizer. Look at the bag. The middle number should be zero. This is the single biggest thing you can do to prevent the toxic algae that shuts the lake down every August.
- Wash your car on the grass. Don't let the soap and grime run into the storm drain. Those drains lead directly to the lake or the Hylebos.
- Join the Friends of Five Mile Lake. Local advocacy is the only reason this park gets funding for improvements like the newer playground equipment and dock repairs.
Five Mile Lake isn't a pristine wilderness. It’s a hardworking, suburban basin that provides a vital escape for thousands of people. Respect its limits, watch the algae blooms, and maybe bring some extra bags to pick up the trash that others leave behind. It’s the only way to keep this little blue-green gem from fading away.
Check the current lake status on the King County "Lake Buoy" website before you head out to ensure the beach is open for swimming. Don't forget your WDFW fishing license if you plan on casting a line; the rangers do check, and the fines are significantly more expensive than the permit.