Lake Chelan Project Relicense Botanical Surveys, 1998

Calypso Consulting was brought under contract with Chelan PUD in March of 1998 to design and execute botanical surveys for the Lake Chelan Project Relicense. A study plan was developed prior to fieldwork and is available from Chelan PUD. Under the study plan Calypso Consulting will provide a rare survey of the shoreline of Lake Chelan from the high water line to thirty feet above the high water line. The survey is a two year project, which commenced in April of 1998. Calypso Consulting has nearly completed the first year’s field survey work, which is summarized below.

Field Methods

Due to the extreme steepness of the terrain along the shoreline of Lake Chelan, a power boat has supported all of the botanical surveys to date. When the terrain allows walking, the shoreline is surveyed on foot, but many areas are too steep or rocky to be walked, and in these areas the boat is used as a survey tool. Since the lake is very deep along the shoreline, the boat can be operated within a few feet of the shoreline vegetation. Binoculars are used to scan the shoreline, and when unusual habitats or unidentified are seen within thirty feet of high water, one or both botanists go on to shore and work on foot. Approximately 60 miles of the shoreline has been surveyed by boat, and 32% of that area, or approximately 19 miles, has been surveyed on foot. This represents well over half of the potential rare plant habitat of Lake Chelan, since most of the lake below Manson is completely developed.

There were three phases to the 1998 rare plant survey: the first phase, in May, focused on habitat for rare annual along the north shore; the second phase, in June, was a more general survey which included much of the south shore; and the third phase, in July, was exclusively focused on seep areas on both shores which might provide habitat for two rare orchids, Spiranthes porrifolia (western lady’s tresses) and Epipactis gigantea (giant helleborine). Some areas were surveyed more than once, if habitat for both early and late season species was present.

Calypso Consulting has also compiled a species list of the shoreline which includes more than 400 species to date. The species list is divided into six sub-areas: #1, downlake of Mitchell Creek and 25 Mile Creek on both sides of the lake; #2, Mitchell Creek to Prince Creek on the north shore; #3, Prince Creek to the National Recreation Area boundary on the north shore; #4, 25 Mile Creek to Graham Harbor on the south shore; #5, Graham Harbor to the National Recreation Area boundary on the south shore; and #6, the National Recreation Area on both sides of the lake.

Findings

Calypso Consulting has found populations of the following rare plants within the Lake Chelan Project area:

Epipactis gigantea (giant helleborine) state sensitive species (common bluecup) state sensitive species brachyptera (Sierra cliffbrake) state sensitive species Silene seelyi (Seely’s silene) state threatened species Spiranthes porrifolia (western lady’s tresses) state sensitive species

Epipactis gigantea is a large member of the orchid family. One population was found during the July survey in a small seep along the Lakeshore Trail 1/4 mile downlake of Stehekin, near the 30 foot

1 elevation above the lake. This population may face threats from recreational use and trail maintenance, but is unlikely to be affected in any way by the Lake Chelan Project.

Githopsis specularioides is a small annual in the bluebell family. Four small populations of Githopsis were found in May between Prince Creek and Moore Point on the north shore of the lake in open grasslands. Although some individual plants are near the high water level of the lake. the greatest threat to these populations is the continued spread of the noxious weed Crupina vulgaris.

Pellaea brachyptera is a dryland which grows in rocky, open areas. The only known Northwestern populations of this fern are in the Lake Chelan area. Calypso Consulting found two populations of Pellaea brachyptera: one in the Prince Creek area and one between Pioneer Creek and Cascade Creek, both on the north shore of the lake. These populations appear stable.

Silene seelyi is a member of the pink family which is only known from Chelan and Kittitas Counties. It often grows on granitic cliffs and talus. Two plants were found on the recent alluvial fan of Canyon Creek, on the south shore of the lake within the National Recreation Area. We suspect that seeds of these plants may have been washed down the creek from a larger population at a higher elevation by a large avalanche which occurred in this creek basin within the last four years. The population is not likely to persist, since natural succession will result in the invasion of trees and shrubs on to the presently open, rocky site. The two plants are at least 10 feet above the high water level of Lake Chelan, and more than 100 feet from the shoreline.

Spiranthes porrifolia is a member of the orchid family which grows in seeps and other wet areas. Four populations were found on the north shore of Lake Chelan between Prince Creek and Moore Point, all associated with seeps above the lake. All four populations are threatened by Crupina vulgaris, and in some areas Crupina appears to be crowding out Spiranthes porrifolia. Some individual Spiranthes plants grow close to the current high water level, but in most cases the populations are 5 to 25 feet above the lake.

In summary, more than half of the natural habitat along Lake Chelan has been surveyed for rare plants. Twelve populations of five rare plant species have been found, mostly on the north shore between Prince Creek and Stehekin. Crupina vulgaris, which is an extremely invasive noxious weed, presents the greatest threat to these populations. No population appears to be threatened at this time by erosion or other processes directly related to the Lake Chelan project.

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