Goodwin & Shoecraft Invasive Plant Control

2023 Invasive Milfoil Update

This year's invasive Eurasian watermilfoil control efforts wrapped up in mid-August. Work included ten days of diver surveying and milfoil removal by Snohomish County's contractor, Lake Defense Force. The work was highly successful as follows: 

Lake Goodwin

In seven days, divers surveyed the entire shoreline and areas of historic hot spots were surveyed twice. Divers found 22 plants. All found plants were hand-pulled. 

Lake Shoecraft

In 2022, the north end of the Lake was densely infested with invasive milfoil and was treated with ProcellaCOR. The treatment was highly successful - in 3 days of diving, the entire shoreline was surveyed and no milfoil plants were found

2023 Milfoil Locations

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2022 Milfoil Locations

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2021 Milfoil Locations

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2023 Fragrant Water Lily Treatment

In response to concerns from lake residents, the advisory committee requested SWM explore options for control of invasive fragrant waterlily in addition to the annual milfoil work. A multi-year chemical treatment was found to be the most effective and low-cost method of control for the 2.2 acres infestation. Imazapyr and Imazamox were selected as the two chemical options as they are both effective with a favorable toxicological profile. In 2022, 2.2 acres of lilies were treated with imazapyr. In 2023, the plants were reduced to 1 acre of lilies which were treated with Imazamox.

Invasive Eurasian watermilfoil (milfoil) and fragrant waterlily are aggressive, non-natives aquatic plant. They grow rapidly and crowds out native plants as they do not have natural predators. Milfoil forms dense mats in the water 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. Fragrant waterlily is an introduced ornamental plant. It takes over shallow areas, limiting habitat and boating and causes the lake to fill in faster than it would naturally. It is Considered a Class C noxious weed in WA state. 


See our aquatic plant page to learn more about  invasive milfoil and fragrant waterlily including how to identify and other aquatic plants. 


How did invasive 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 invasive aquatic plants?

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. In 2022, the group also included control of invasive fragrant waterlily in their efforts. See below for more information on past efforts. 


Past Milfoil Control Efforts

Aerial View of Containment Curtains on Lake Shoecraft

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.

Man Holding Burlap Barrier from Boat Side
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. 
Milfoil Removal Boat
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 invasive aquatic plant 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 invasive plant 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. Prior to 2020, efforts were beginning to fail due to rising costs allowing for fewer days of diving. In addition, herbicide treatments were less effective stemming from increased herbicide resistance. 


However, the community helped to increase fees to restore diving services to their previous level. In addition, a new herbicide, Procellacor was developed for milfoil control which has been highly effective. Collectively, these two efforts have kept milfoil efforts at their lowest levels since control work began. In addition, sufficient funds have allowed for the inclusion of fragrant waterlily control as well.  You can see milfoil locations over the years in the milfoil location maps for Lake Goodwin and Lake Shoecraft

A History of 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. 
  • 2013A 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 2020-2025 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. 
  • 2019 - A 30-acre herbicide treatment was conducted on the two lakes (12 at Shoecraft; 18 at Goodwin) with the herbicide ProcellaCOR. This treatment was highly effective at reducing milfoil in both lakes.
  • 2022 - An 8-acre patch of milfoil on the north end of Lake Shoecraft was treated with the herbicide ProcellaCOR.
  • 2022 - 2 acres of Fragrant waterlily on Lake Shoecraft were treated with the herbicide imazapyr.
  • 2023 - 1 acre of Fragrant waterlily on Lake Shoecraft was treated with the herbicide imazamox.