Devils Lake Aquatic Vegetation Management Update

Elodea, also known as Canadian waterweed, is an aquatic plant that is native to North America and is now found in many parts of the world. It is often considered a nuisance because it can grow quickly and form dense mats that can interfere with recreational activities and harm wildlife habitats. In addition, it can also outcompete native plants, leading to a decline in biodiversity. Elodea was first identified in Devils Lake in 2019. Since then, Elodea growth has exploded in Devils Lake. Multiple in water vegetation management options exist but not all options work for all water bodies. Given the mixed use of Devils Lake the options below were identified as being the most appropriate methods to manage the nuisance aquatic vegetation growth for our basin.

Chemical control: Herbicides can be used to kill elodea, but they must be used carefully to avoid harming other aquatic plants or animals. After an initial pilot project involving small control areas in Devils Lake it was determined chemical control was not an effective method large scale vegetation control for our water body. However, some success has been found using the chemical herbicide “Dibrox”.

Mechanical removal: This can be done by hand or with special tools, such as rakes or harvesters. It’s important to remove all of the plant material, including roots and fragments, to prevent regrowth. In 2021 the Devils Lake Water Improvement District leased and began operating an aquatic harvesting boat. More details about the districts mechanical vegetation removal efforts can be found here: https://dlwid.org/current-projects/.
Biocontrol: Some species of fish and insects feed on elodea and can help control its spread. Sterile grass carp have been an effective in water vegetation management tool for Devils Lake in the recent past. In June of 2023, 5,000 grass carp were added into the lake. DLWID will perform an annual survey to measure the effectiveness of the grass carp. https://dlwid.org/current-projects/.

Lake Conservation Aeration Project 2 Year Update

Long-standing concerns in the watershed that affect Devils Lake continue to be ongoing inputs of creek-borne, E-coli bacteria from Thompson and Rock Creeks, historical and on-going lake-wide inputs of nitrogen and phosphorus from residential septic systems, increasing sedimentation, erosion, storm water inputs, intermittent cyanobacteria blooms, and the threat of the return of nuisance aquatic plants.The Devils Lake Water Improvement District, after a lengthy period of research and committee/board discussion, agreed to fund an updated and comprehensive study to characterize the quality of Devils Lake as a primary source of habitat and recreational opportunity.In November of 2014, a request for proposals was issued nationally to some 60 firms that exhibited broad expertise in lake water quality study, design, and improvement. In February of 2015, a bid opening was conducted with no proposal responses. In March of 2015, DLWID approved a direct appointed concept, pursuant to State of Oregon, Sole Source policies, rules and law. In July of 2015, DLWID received a proposal from Alex Horne and Associates (AHA) of California to study and report the past and current state of Devils Lake, provide options for lake water quality improvement, and narrow the options to a recommended solution. The July 2015 proposal cost was, through negotiation, reduced sufficiently to allow the DLWID Board in February 2016 to approve the amended proposal and enter a contract with AHA and their design team subcontractors.The AHA Phase 1 Report was completed in mid-April 2016. This level of completed work provided the complete scientific study portion, a solution menu of 17 options, and once oxygenation by aeration was selected as the appropriate course of action. click links below for more info and images.

Aeration-Project-AAR-2-Year-Update-Complete-PDF