Sloan's Lake Environmental Assessment

Sloan’s Lake is a shallow urban lake that has accumulated a significant amount of sediment over the past several decades, resulting in an average water depth of 3.5 feet deep across the lake. In 2020, Denver Parks and Recreation (DPR) partnered with the Denver Department of Public Health and Environment (DDPHE), Denver Department of Transportation and Infrastructure (DOTI) Wastewater Management, and the Mile High Flood District (MHFD) to evaluate the existing conditions of the lake that contribute to an increased occurrence of algae blooms, fish kills, and other aquatic habitat health concerns.

SloansLake-ExistingConditions.pdf(PDF, 18MB)

DPR has contracted an environmental consulting firm to perform an assessment of Sloan’s Lake.  This analysis includes bathymetric mapping (a topography map of the lake floor), water quality sensor installation and analyses, and sediment sampling.  Water quality sensors were installed summer 2021 to collect real-time data of the water conditions within the lake.  Analysis of this data will assist in understanding the existing conditions along with changes over time to guide decision making on how to best manage the lake. 

Sediment Sampling Results and Recommendations.pdf(PDF, 5MB)

DPR is also coordinating with the MHFD to analyze the quality of water entering the lake. This study includes the watershed outside of the City and County of Denver in Lakewood, Wheat Ridge, Jefferson County, and Edgewater.

Sloan's Lake Drainageway Sediment Supply Assessment Memo

The results of the Sloan’s Lake Environmental Assessment culminated in a series of Water Quality Interventions that could be implemented around the lake in phases. The interventions fall along a spectrum of more nature-based solutions to more engineers solutions. The interventions include the following:

1. Bank Restoration: to repair damaged retaining walls and prevent shoreline erosion.
2. Floating Wetlands: to install wetland plants to absorb excess nutrients in the water. A demonstration of floating wetlands was installed in the southwest corner of the lake during summer of 2024.
3. Water Quality Wetlands: to implement green infrastructure and wetland plants to filter water from the storm sewer systems that discharge into the lake.
4. Landscape Transformations: to increase the wetland and riparian buffers of native plants along the shoreline to filter stormwater run-off into the lake.
5. Habitat Structures: to support fish and wildlife that live in and around the lake.
6. Water Quality Nutrient Treatments: an annual treatment applied to the lake in mid-summer to reduce the amount of phosphorous available for bluegreen algae, hopefully slowing down its growth and reducing future harmful algae blooms. These treatments have been occurring on the lake since 2022.
7. Water Quality Infrastructure: to capture sediment entering the lake from the Sloan’s Lake Drainageway or Ashland Drainageway and allow for access to routinely remove this sediment similar to a stormwater detention basin.
8. Sediment Removal: often referred to as “dredging” to remove the sediment that is currently within the lake above the “historic” lake bottom as determined by the bathymetric survey.

Sloans Lake Water Quality Interventions.pdf(PDF, 24MB)

DPR along with partners DOTI, DDPHE, and MHFD are currently scoping the design of “Phase 1 Sloan’s Lake Water Quality Improvements” based on the Environmental Assessment Intervention documents.  These improvement may include water quality infrastructure, wetlands, landscape transformation, and bank restoration. The intent of these interventions are to capture new sediment from entering the lake and treat stormwater through wetlands to remove excess nutrients as it enters the lake.  Due to budget limitations at this time Phase 1 will not include significant sediment removal.  The project partners would like to remind the community that dredging of the lake without treating new stormwater entering the lake will not solve the challenges Sloan’s Lake faces. The lake needs a wholistic approach blending at least some aspects of all of the different water quality interventions to ensure a sustainable future for the Lake.

DPR’s Lake Management team will continue to apply annual Nutrient Treatments on the lake in mid-summer to reduce the amount of phosphorous available for bluegreen algae, hopefully slowing down its growth and reducing future harmful algae blooms.

At the first Community Meeting about the Sloan's Lake Environmental Assessment, we shared existing conditions that will guide initial concept design alternatives to create a vision for the future of the lake.

• View the meeting recording in English
• View the meeting presentation(PDF, 35MB)

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En la primera reunión comunitaria sobre la evaluación ambiental de Sloan's Lake, compartiremos las condiciones actuales que ayudaran crear alternativas para el concepto inicial de la visión para el futuro del lago.

• Vea la primera reunión comunitaria en español