Cascade Water Alliance, which owns and operates the Lake Tapps Reservoir, conducted a milfoil survey in June. Based on that survey and information received from residents throughout the year, Cascade is announcing its planned milfoil treatment for 2025.
Milfoil is found in most Northwest lakes and has been in the Lake Tapps Reservoir for decades. Cascade has no legal obligation to address milfoil; however, Cascade believes treating milfoil keeps the reservoir healthy. Cascade has treated and addressed milfoil management annually since 2010.
The areas designated to receive treatment in 2025 are marked on the attached map. Treatment is scheduled for the week of June 23-27, and residents in planned treatment areas will be notified regarding the date of treatment prior to actual application.
Cascade will be using ProcellaCOR®, an aquatic herbicide approved by the State Department of Ecology. Cascade has used this herbicide to treat the reservoir since 2019, with good results. It is environmentally friendlier than herbicides used in the past, and results have been significantly better. This treatment may affect water that is used for irrigation, but, as a reminder, pumping or drawing Lake Tapps Reservoir water for irrigation is not permitted.
Although Cascade can treat much of the milfoil in the reservoir, it doesn’t have the funds to treat all impacted areas, such as small patches that affect a limited number of homeowners. To address these needs, and per the request of some Lake Tapps homeowners, Cascade allows homeowner associations (HOAs) and individual homeowners, at their own expense, to use Cascade’s permit and contract directly with its contractor to chemically treat milfoil in front of their residences. Treatment will be limited to milfoil and will not include other non-native or native plants, and must occur the same days as Cascade’s planned treatments. If you have milfoil that is not in our planned treatment areas and you would like to pay for it to be treated, please visit our website for more information. https://cascadewater.org/lake-tapps/milfoil/
If property owners plan to remove aquatic plants from the Lake Tapps Reservoir in front of their property, they must follow the rules outlined by the Washington State Department of Fish and Wildlife (WDFW). Additional information can be found here: https://wdfw.wa.gov/licenses/environmental/hpa/types/aquatic-plants. The WDFW rules can be found in the Aquatic Plants & Fish Pamphlet: https://wdfw.wa.gov/publications/01728
In addition, Cascade has teamed up with the Tacoma-Pierce County Health Department to offer residents TappsWise, a natural yard care and septic system maintenance program to keep the Lake Tapps Reservoir clean and healthy. Additional information about TappsWise can be found here: https://www.tpchd.org/healthy-homes/tappswise
For more information, visit https://cascadewater.org/lake-tapps/milfoil/
