Goodwin & Shoecraft Invasive Milfoil Control
2020 Milfoil UpdateThis year's invasive Eurasian watermilfoil control efforts wrapped up in mid-August. Work included ten days of diver surveying and milfoil removal by Seascapes Aquatic Services. We are happy to report that the milfoil levels are at their lowest since control work began in the mid 1990's. The low number of plants is a results of the 2019 Procellacor herbicide treatment which was highly effective. The results from the 2020 survey are as follows:
In seven days, divers surveyed the entire shoreline and areas of historic hot spots were surveyed twice. Only 30-40 milfoil plants were found as shown in the map. All found plants were hand-pulled or removed using Seascape's diver suction harvesting technology.
In 3 days of diving, the entire shoreline was surveyed twice including an intense survey of the northern cove. Only one milfoil plant was found and removed. A big thanks goes out to the resident who allowed for the use of their private launch to complete this year's work!
What is milfoil?
Eurasian watermilfoil (milfoil) is an aggressive, non-native aquatic plant. It grows rapidly and crowds out native plants, forms dense mats and produces long tendrils that entangle fishing lines, boat motors and swimmers. Milfoil spreads easily to other lakes from small fragments left on a boat motor, boat trailer or fishing equipment. It is considered a Class B designated noxious weed in Snohomish County. See our aquatic plant page to learn more about milfoil and how to tell it from other aquatic plants.
How did milfoil reach the lake?
Eurasian watermilfoil invaded Lake Goodwin in the early 1990s. The largest initial infestations were close to the boat launch indicating milfoil was likely brought in by a boat or other recreational equipment. Milfoil most likely spread to Lake Shoecraft through the canal that connects the two lakes. By the end of the 90's the entire north and south ends of Lake Shoecraft had dense milfoil growth.
What is being done about milfoil?
Since the mid-1990's, Snohomish County and the Lake Goodwin and Lake Shoecraft communities have worked together each year to control milfoil. The County manages the control work with direction from the 7 Lakes milfoil advisory committee, a volunteer group composed of Lake Goodwin and Shoecraft residents. The milfoil control strategy includes the following efforts:
1) prevention - removing plants before launching a boat and again when leaving the lake
2) diver hand-pulling - annual pulling of small patches and scattered milfoil plants
3) herbicide treatments - when areas are too large or dense for hand-pulling
In 2000, control began at Lake Shoecraft with an herbicide treatment where 2,100 feet of curtains were used to contain the herbicide in the infested areas. The treatment eradicated milfoil for 8 years.
Lake Goodwin milfoil control work began in 1997 when 226 burlap sheets were installed covering two acres of milfoil. While effective, this approach proved too labor intensive to be used on a large scale.
Since 1997, divers survey Lake Goodwin and Lake Shoecraft for milfoil. When they find a plant, they dig out the roots and pull teh plant. They carefully bag it as each small fragment can start a new plant. This strategy combined with occasional herbicide treatments has kept milfoil to low levels in most years.
How much does this cost and who pays for it? This control work is funded through Snohomish County Surface Water Management (SWM) utility service charges and local residents. Local residents pay an aquatic plant management service charge, established in 2005 by Snohomish County Council (SC25.20.050). It was established per the request of residents to replace an administratively costly Lake Management District. The charge was renewed in 2010, 2015, and 2019.
The annual cost of milfoil control has ranged from $45,000 to $65,000 from 2016-2019 depending on the number of days with diver hand-pulling and if herbicide treatments are used. The charges paid by residents cover around $31,500 of the total cost and the remainder has been paid for by Snohomish County SWM utility service charges.
Are milfoil control efforts working?
Over the last two decades, milfoil control efforts have largely succeeded as milfoil has been maintained at low levels in most years. You can see milfoil locations over the years in the milfoil location maps for Lake Goodwin and Lake Shoecraft. However, in recent years it has been increasingly difficult to meet milfoil control plan goals because of:
- Warmer, earlier springs that result in a longer milfoil growing season
- Less effective herbicide treatments stemming from increased herbicide resistance
- Fewer days of diver hand-pulling due to rising costs of diver services
A History of Control Efforts
Here are some additional milestones in addition to annual control efforts.
Here are some additional milestones in addition to annual control efforts.
- 1996 - The County applied for and was awarded an early infestation grant through the Department of Ecology for the development of an Integrated Aquatic Plant Management Plant.
- 1996 - The 7 Lakes Milfoil Advisory Committee was formed with volunteers from several lakes. Together with the County, they began efforts to control milfoil and develop the plan.
- 1997 - Lake Goodwin control efforts began with the installation of two acres of burlap bottom barriers. Divers spent two weeks placing the 226 sheets anchored with sandbags. While effective, the strategy proved to be too labor intensive for relatively small areas of control.
- 1997 - Diver hand-pulling at Lake Goodwin also begins. This strategy of using divers to remove scattered plants or small milfoil patches successfully maintains milfoil at acceptable levels for almost a decade.
- 1999 - The 7 Lakes Integrated Aquatic Management Plan was completed. The plan still serves as a blueprint for milfoil prevention and control efforts on the two lakes.
- 2000 - Lake Goodwin and Shoecraft Lake Management District was established as a mechanism for area residents to help fund milfoil control efforts as grant funding had been exhausted.
- 2000 - Lake Shoecraft control efforts began with a 25.5-acre Fluridone herbicide treatment. The herbicide was concentrated in the areas of infestation by two curtains totaling 2,100 feet. This unique strategy successfully eradicated the plant until a 2008 re-introduction.
- 2005 - The Lake Management District proved to be administratively costly to set up and administer. Per the request of lake residents, Snohomish County Council replaced it with an aquatic plant control service charge (SC25.20.050) which was renewed again in 2010 and 2015.
- 2006 - A 7-acre patch of milfoil was discovered in a shallow offshore area in Lake Goodwin and was treated with the herbicide, Renovate. Subsequent annual hand-pulling seems to have eliminated milfoil in this area, though it remains susceptible to infestation.
- 2008 - A few milfoil plants were discovered in Lake Shoecraft near the inlet from Lake Goodwin and annual hand-pulling by divers begins in the lake.
- 2013 - A 25-acre herbicide treatment was conducted on the two lakes (12 at Shoecraft; 13 at Goodwin) as many milfoil patches were too dense for effective diver hand-pulling.
- 2016 - A 7.9 acre patch of milfoil on the north end of Lake Shoecraft was treated with the herbicide, Renovate Max G after the area again became too dense for hand-pulling. The treatment only lasted a few years and by 2018 several areas of the lake had developed dense milfoil patches.
- 2019 - With support from the Lake Goodwin and Shoecraft community, the Snohomish County Council renewed the aquatic plant control charge for 2020 and increased the charge to restore milfoil control efforts to historic levels and to establish a reserve fund to more quickly respond to larger infestations.