"A lake that used to be 12 feet deep is in some places only 4 feet deep," Mayor Mike Johnston said from the shore of Sloan's Lake on September 2. "It affects the lake's health. It affects algae blooms. It affects our most beloved events."
The headline that followed was about dredging. Dredging is the part of the plan furthest away. It still needs two approvals, and under the city's own timeline it would start no earlier than 2028. Denver's lake planners have said for some time that the first job is elsewhere, at the inlets where the mud comes in. That inlet work is what will reach the loop first.
Where the Mud Comes From
The lake isn't filling in from within. Big parts of Denver, Edgewater, Lakewood and Wheat Ridge drain into Sloan's Lake, and that runoff carries sand, sediment and street grime that has slowly built up on the bottom. The city's September announcement compares today's depth with historical depths of 8 to 12 feet. It says many areas now average 2.5 to 3 feet. The Denver Post puts the average at about 3 feet across the 177-acre lake. Denver Parks and Recreation's assessment page gives 3.5 feet. The exact number depends on who is measuring. Either way, the lake is roughly a quarter to a third as deep as it once was.
Shallow water warms quickly. The Post describes that warm water as hard on fish and an easy place for algae blooms to grow. The city adds that the sediment lowers oxygen, kills fish, and reduces the lake's drought tolerance and its capacity to absorb stormwater.
The Colorado Dragon Boat Festival has already felt this. In 2025 it moved from its usual late-July weekend to September after Parks and Recreation raised concerns that included dead fish, warm and shallow water, blue-green algae blooms and untreated runoff. The festival came back on August 29 and 30 this year. In May, the department told the Post there were no signs of blue-green algae and that it planned phosphorus treatment before the event.
The City's Own Order of Operations
The city's lake work has run on the Sloan's Lake Environmental Assessment, which started in 2020. Parks and Recreation partnered with the Department of Public Health and Environment, Wastewater Management and the Mile High Flood District. Water quality sensors have been collecting real-time data since summer 2021. A separate study with the Mile High Flood District tracked sediment coming from the parts of the watershed in Lakewood, Wheat Ridge, Jefferson County and Edgewater.
The assessment ended in a menu of eight interventions, ranging from planting to heavy engineering:
- Bank restoration to repair damaged retaining walls and stop shoreline erosion.
- Floating wetlands that pull excess nutrients from the water.
- Water quality wetlands that filter storm sewer discharge before it reaches the lake.
- Landscape transformations that widen native shoreline buffers.
- Habitat structures for fish and wildlife.
- An annual midsummer nutrient treatment to limit the phosphorus that feeds blue-green algae.
- Water quality infrastructure that catches sediment from the Sloan's Lake and Ashland drainageways in a basin crews can clean out.
- Sediment removal, meaning dredging down to the historic lake bottom identified by a bathymetric survey.
Some of these are already in place. Nutrient treatments have been applied every summer since 2022. A demonstration of floating wetlands went into the southwest corner of the lake in summer 2024.
The next step is Phase 1, paid for with $5 million in Vibrant Denver bond funds that voters approved in 2025. It is aimed at the edges and the inlets: bank stabilization, erosion repair, landscape transformation, wetland habitat, green stormwater infrastructure and sediment forebays. As of late summer 2026, design was moving toward the 60% mark. The same page says plainly that because of budget limits, Phase 1 will not include significant sediment removal. It also explains why the city considers that order correct:
"Dredging of the lake without treating new stormwater entering the lake will not solve the challenges Sloan's Lake faces."
Put another way, deepening the lake without first catching what washes in would set the clock back to zero and let it start running again.
The Money That Would Pay for the Dredge
The September announcement is what would make dredging possible. The city proposed a $50 million project with three funding sources:
- Up to $40 million from the St. Anthony Urban Redevelopment Area, which was created in 2013 to support redevelopment around Sloan's Lake.
- $5 million from the Vibrant Denver bond.
- About $5 million from the city's Wastewater Enterprise Fund.
That would be a major step, but it falls short of the full job. The Post reports the restoration has been estimated at $130 million or more overall. The city describes the $50 million as a way to "begin removing sediment" and to test dredging methods in a busy urban park that could later apply to other Denver lakes.
The $40 million needs approval from the Denver Urban Renewal Authority board and the Denver City Council. DURA set a special board meeting for September 14, with a resolution on committing funds to a project in the St. Anthony area on the agenda. As of early October, DURA's meeting page lists that agenda but no minutes or result. No related item has appeared on City Council agendas through the October 5 meeting. The dredging money should be treated as pending.
If both approvals come through, the city expects to award a contract and complete permitting with the U.S. Army Corps of Engineers in 2027, then start work in 2028. The Post's September story gave 2027 for the construction start. The city's release is more specific. Per the Post, the work may divide off sections of the lake without draining it, and the goal is to keep as much of the park open as possible.
What Is Actually Changing on the Loop
On a walk around the lake this fall, the changes you'll see have nothing to do with dredging. They are maintenance and building projects at the edges of the park.
Southwest corner, Sheridan Boulevard and 17th Avenue. In September 2026, Parks and Recreation closed the parking lot and basketball court here so it could turn the nearby building into a maintenance facility for northwest Denver parks. Part of the trail will close later in construction. The closures are expected to last through early 2027, with signed detours. This is the same corner as the 2024 floating wetland demonstration.
North tennis and basketball courts. These courts are being replaced with better accessibility, paid for with Parks capital funds and the RISE Denver Bond. The city's schedule shows construction starting in winter 2026 and finishing in fall 2027.
The historic Boat House, near Wolff Street and West Byron Place. Right now Parks Operations, Adaptive Recreation and Park Rangers use the building. Plans call for turning it into a 2,500 to 3,000 square foot community and event space connected to the marina. The design team presented its preferred concept at a third open house on January 29, 2026. The city's project page doesn't give a construction date yet.
For anyone who spends time on or near the water, Denver's general guidance still applies. Blooms that look like green paint can contain toxins, and the city samples Sloan's Lake from time to time between May and October.
Reading the Calendar Forward
Lined up together, the dates put the inlet work first and the dredging last:
- Now through early 2027: Southwest corner lot and court closed. A trail segment closes later.
- Winter 2026: North courts construction begins.
- 2027: Contracting and Army Corps permitting for the dredging project, if DURA and Council approve.
- Fall 2027: North courts finished.
- 2028: Earliest start for dredging, under the city's timeline.
Phase 1 design, with its forebays, wetlands and bank repairs, was already heading toward 60% before the dredging announcement. That puts it on a separate track that doesn't depend on DURA's decision. Afterward, the city's stated goal is a lake safe for paddleboarding and boating. Swimming is not part of that goal. The Sloan's Lake Park Foundation turns 10 this year. It has asked the community to keep pushing for the project through construction. Executive Director Kurt Weaver called the chance "to write a new future for the lake" massive for the neighborhood. The city says Sloan's Lake draws 2 million visitors a year.
For more on the area, see our Sloans Lake and West Highlands neighborhood guide and our earlier weekend guide to Sloans Lake and Highlands Square.
If you own near the lake and want to talk through how a park project lasting several years could affect your timing, the partners at Helm Weaver Helm follow these approvals closely and are glad to walk through them with you. Book an Appointment.
