PROBLEM STATEMENTBrazilian Elodea

Lake Leland Integrated Aquatic Plant Management Plan

 


In January of 1998 at the second meeting of the Lake Leland steering committee, members established a list of problems related to invasive aquatic vegetation. Many of these problems had been previously identified at meetings of the Leland Neighborhood Improvement Club and at a public meeting in August 1997, which specifically addressed invasive vegetation in Lake Leland. The identified problems are related to three invasive weeds: Brazilian elodea (Egeria densa), reed canary grass (Phalaris arundinacea), and yellow flag iris (Iris pseudacorus). The problems associated with each species are discussed below.

BRAZILIAN ELODEA

In the summer of 1994 during a routine Department of Ecology aquatic plant survey of Lake Leland, the presence of Brazilian elodea was first officially noted. This noxious, non-native, invasive species has been spreading at a steady rate and is rapidly filling in the shoreline up to a depth of about ten or eleven feet. In the last four years, Brazilian elodea has become well established in the south end of the lake, and plants are now found scattered along the perimeter of the rest of the lake (Figure 1). Fishing, boating, and swimming have been affected due to the density of the plant. Many private docks have become totally surrounded with this noxious weed, which hampers safe swimming.

Jefferson County Parks and Recreation provides a campground and maintains a swimming area and boat ramp at the lake. Brazilian elodea has now been found along the shoreline of the park which could eventually hinder safe swimming in that area. The rapidly spreading weed could result in less use of the county campground, which is a source of revenue to Jefferson County Parks and Recreation.

The community feels that their property values could be lowered by the steady encroachment of the weed. Another concern is that Brazilian elodea could alter the ecological balance of the lake, affecting fish and wildlife habitat and the excellent warm water fishery that presently exists at the lake.

A very important concern of the committee is the potential for the spread of Brazilian elodea to other lakes in the surrounding area. This noxious weed is easily transported to other locations on boat motors, trailers, and fishing gear and is known to establish new infestations from plant fragments. There are several lakes in the area that currently are not infested with Brazilian elodea, one of which is Crocker Lake, located just three miles north of Lake Leland. Fishermen are known to utilize both lakes in the same day.

A final concern is that the methods chosen to control invasive plants in the lake do not jeopardize the water quality of the lake. Lake Leland is a source of domestic water for some residents, and the community is particularly concerned about using broad spread chemical treatments which might compromise human safety.

REED CANARY GRASS

Reed canary grass, another exotic species listed by the state as a noxious weed, is also a problem at Lake Leland. This water tolerant grass, introduced into the area to provide forage for livestock in wet areas, is notorious for growing in stream channels and causing drainage problems. Canary grass grows densely in the upper 2000 feet of Leland Creek and is a major factor in causing the flooding problem and high water level in Lake Leland. Beaver dams on Leland Creek also contribute to the problem.

The steering committee has thoroughly discussed the history of the flooding problem, which has occurred for a long time. During the late 1940’s the Soil Conservation Service (SCS) assisted local farmers in dredging out the inflow and outflow channels to the lake. According to long time resident Hector Munn (Munn 1986), the lake level dropped dramatically for several seasons, enough so that docks had to be extended to reach the water level. One could walk through the culvert under Leland Valley Road West. The road is now flooded most of the winter and spring, and the culvert is full all summer long. However, the dredging was only a temporary fix. In April of 1988, the SCS again addressed the drainage problem and provided an analysis (Appendix A). The SCS had no solutions to recommend due to environmental factors, permit systems, and federal and state regulations regarding wetlands. Recurrent flooding over Highway 101 north of the lake prompted the Department of Transportation to look for a solution to the rising water table in late 1990. The Jefferson County Conservation District served as lead agency and identified removal of canary grass, a beaver dam, and natural obstructions as a first step in the solution. In the fall of 1991, a Leland Creek channel restoration project utilizing an excavator and a "Cookie Cutter" (a flat bottomed boat used to cut vegetation in lakes) cleared canary grass from the 2000 foot section of Leland Creek below Lake Leland and, as a result, the lake flowed steadily through the outlet. The lake water level dropped dramatically for a few years but has since returned to previous levels (see Figure 12 in Watershed Characteristics). Flooding was only temporarily reduced, because problems of funding, responsibility, and permitting plagued the project and prevented continued maintenance to ensure that the outlet remained open.

Seven years later the issue has not resolved itself. The outlet channel is again virtually clogged with canary grass and the flooding problem has been increasing. Over the past three years the lake level has continued to rise. The higher water table has contributed to flooded roads (county and state) and septic drainfields. The latter could result in the release of nutrients and fecal coliform bacteria to the lake. To date, two homes have been flooded and others are at risk. Several properties are in jeopardy and useable farm lands have decreased. Dead trees resulting from a high water table can be seen around the shoreline. Since it has been demonstrated that improved drainage reduces the lake water level, neighbors regularly patrol Leland Creek for obstructing beaver dams. And they continue to look for feasible solutions to control the canary grass.

It should be noted that the Washington Natural Heritage Information System database lists the presence of bristly sedge (Carex comosa), a state sensitive plant species, in the wetland at the south end of the lake and along Leland Creek. Although the Natural Heritage Program has no regulatory authority, the Leland community wishes to respect the uniqueness of the Leland ecosystem and will plan any canary grass controls with respect to this information.

YELLOW FLAG IRIS

Yellow flag iris, a non-native invasive species not listed on the state noxious weed list, has been spreading in some areas of the lake shoreline. The density of the iris along the shore crowds out native vegetation and can impede human or wildlife passage.


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Questions about this page?
Contact Kathy Hamel by e-mail at kham461@ecy.wa.gov