Proposals

Weed Removal

Recent Lake History

2009

Small patch of Elodea near SW corner of lake

Removed in one easy session

2010

Feb, Mar, Apr: Lake shallow, little wind, much sunlight

Filamentous algae covers bottom of lake

May: Lake rises. Water very clear and stays that way, except for algae blooms

June 20, first report of weeds (minimum of 150 plants counted)

June 26 & 27, first and second work parties. All curley leaf pond weed removed with some Elodea & Najas

July 3, Third work party. All weeds (Elodea & Ceratophylum) removed from Nick Welsh Park and East Islands.

July 23, Algea alert posted.

Control of Weeds and Algea

Four approaches: Do Nothing, Biological, Physical, and Chemical

Do Nothing: Lower Lake as usual

Pro: Might get better naturally, i.e. freezing, cold, cloudy fall and winter (normal weather pattern), plants will die
back during winter

No financial costs

Con: Could get worse

Biological: Grass Carp

Not likely to be approved

Physical: Raking, Mats, Harvester, Drain Lake

Raking:

Pro: Has worked in the past, can be done by individuals around your own docks.

Con: Labor intensive, Need boats, equipment, cloudy (turbid) water, place to off load weeds. This is now a huge
project for the lake. All raked plants grew back this year.

Mats:

Pro: Very effective,

Con: Cover 10’ x 40’ for about $200. Reusable, but shouldn’t be walked on or caught in outboard prop. Probably
up to individual property owner to purchase and manage.

Harvester:

Pro: Cuts off weeds near bottom, removes nutrients from lake.

Con: May spread small pieces around lake to reroot, where to dock, unload veg, hire an operator, costly (New,
$80,000 – 225,000) I think we might be able to lease one, may be hard to manage around docks.

Drain the Lake:

Pro: May kill the most weeds

Con: Would need long dry period (a month of summer), pumps needed to get all water out (noise, cost), will move
or kill fish and wildlife. May need to use chemicals to kill roots before draining a second summer.

Increase turbidity of the Lake: Dragging chains between two boats

Pro: If this does increase turbidity, removal of weeds might stay in check.

Con: Weeds and filamentous algae must be removed first, stirring lake bottom will bring nutrients to surface and
lead to more blue-green algae problems.

Chemicals: A NPDES permit maybe required ($600), our weeds dictate which chemicals might be used.

Spot treat individual plants or small areas early summer:

Pro: Might clear weeds of a few areas, like the island canals, east canal, and bay at south east end of lake. About
10 acres total, Sonar does not have restrictions for swimming or animal drinking.

Con: 5 acres minimum need to be treated to offset dilution (except island canal), Sonar may take 1-3 months to
kill plants, cost about $5,000 for 10 acres, spot treating does not guarantee that the plants won’t come back next
year, may need a certified applicator to spread chemical.

Treat entire lake:

Pro: Might remove most weeds/algae. With strong summer winds we might get turbid water.

Con: Kills weeds in a month or three, cost: $50,000 for chemicals to kill weeds, $25,000 to kill algae (if legal), may
have to be repeated, may have to lower lake to save $, certified applicator, boats, dead weeds may make lake
smell, will affect fish and wildlife.

Recommendations:

See what things look like in March/April. Hold another general meeting to make a decision on course of action.
Begin action in June if necessary.

Useful websites: I found these very useful

Aquatic Plant Management –

Lake bottom mats

www.lakebottomblanket.com

www.weedersdigest.com

Harvesters:

www.weedharvesters.com

Aquatic Herbicides

www.ecy.wa.gov/programs/wq/plants/management/aqua028.html

www.killlakeweeds.com Aquacide Company

Aquatic weed consultants

www.aquatechnex.com