Save Union Bay Association 2012 Report and
Recommendations
AquaTechnex, LLC
Prepared for Save Union Bay Association
Headquarters
Bellingham, WA 98228
360-527-1271
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Introduction
Save Union Bay Association (SUBA) is comprised of the homeowners along the northern shore of Union
Bay. This portion of Lake Washington has been severely impacted with invasive aquatic weeds for a
number of decades. The dominant species are Eurasian Milfoil and White Water Lily. There have also
been scattered infestations of Brazilian Elodea noted throughout the Bay.
The Save Union Bay Association board had secured funding to complete an Integrated Aquatic
Vegetation Management Plan (IAVMP). This process is encouraged by the Washington Department of
Ecology. The preferred control strategy that came out of this process was to use fluridone or Sonar
Aquatic Herbicide to target the Eurasian Milfoil and Brazilian Elodea present throughout the bay, and to
use glyphosate herbicide to target White Water Lily infestations. The IAVMP also proposes actions and a
budget for the years through 2020.
SUBA published a request for proposal to implement this plan and Aquatechnex LLC was the successful
respondent to this request. During the spring and summer of 2012, Aquatechnex implemented the
tasks outlined in the IAVMP to the waters of Union Bay. Specifically these included survey and mapping
of pretreatment conditions, development of a treatment strategy using Sonar Precision Release aquatic
herbicide, application of Sonar in four treatments, monitoring of herbicide levels and water quality
parameters, treatment of white water lily growth, public information as required by the permit and a
post treatment survey and report.
This report will present our work for the summer of 2012.
2012 objectives
The Recommended Aquatic Vegetation Control Plan from the IAVMP selected Sonar as treatment
scenario 3 and White Water Lily control with glyphosate. The primary goal is stated to be suppression of
Eurasian milfoil with a secondary goal of suppressing potential future colonization of Brazilian Elodea
populations. The plan further indicates that suppression means limiting target plant growth and density
to a population that does not impede recreation or present a swimming safety risk.
Sonar Precision Release or PR was selected as the primary tool in this mission. Fluridone as an active
ingredient in this herbicide has to remain in contact with target vegetation for a number of weeks. In
large lake system with extensive water exchange, dilution can reduce concentration if one time
applications are made. Sonar PR does not deliver the entire herbicide load of the pellet on application,
it is a controlled release formulation that doses the treated area over a 2‐3 week period. A number of
applications are made at approximately 2‐3 week intervals to maintain dose rates.
Glyphosate is broad spectrum liquid herbicide that is sprayed directly onto target lily pads. This material
is applied with an aquatic surfactant to enhance penetration and translocation within the lily growth.
Generally, large areas are not treated all at one time if the lake bottom is heavy in organic materials.
Instead a yearly program of reducing growth gradually is considered a better approach.
LegendHabitat Types IAVMPHabitat
Emergent and Scrub Shrub WetlandWetlands: emergent and scrubshrub
Scrub shrub and forested WetlandWetlands: scrub shrub andforested
High density invasive submerged vegetationInvasive submerged aquaticplants (high density)
Invasive Submerged Plants Low to Medium DensityInvasive submerged aquaticplants (low to medium density)
Mixed Native/Invasive
Mixed native and invasivesubmerged aquatic plants(high density)
Native Submerged Plants Native Submerged PlantsNo Plants (Dredged); No Plants (Managed) No plants (dredged or managed)
White Water LilyFloating leaved aquatic plants,primarily white water lily
SUBA Implentation of IAVMP ProgramOriginal Map Data Set from IAVMP
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The IAVMP stated that expectations for the year would be that there would be a widespread loss of
Eurasian Milfoil within the treatment area. There will also be an impact on Brazilian Elodea and in some
cases to more sensitive native aquatic plants. The report further concluded that there may be several
small patches of Eurasian Milfoil likely to remain within the control zones after the first year of
treatment. Given the widespread infestation of noxious aquatic weed growth elsewhere in Lake
Washington the goal of this project is not eradication, it is suppression.
With that direction in hand, our team developed and implemented the following program during the
summer of 2012.
Methods
Our first step was to develop a Geographic Information System (GIS) project. We obtained the Herrera
GIS layers from their mapping work in the development of the IAVMP. We also selected imagery
background layers and built a sampling grid.
In early May, our team mobilized two mapping vessels to the area and travelled transects to map
current conditions throughout the proposed treatment area. Eurasian Milfoil dominated the western
half and off shore areas of the bay. As we moved east, milfoil was still dominant, but well mixed with
native aquatic plant growth and Brazilian Elodea in deeper water. We used this data to finalize a
treatment protocol.
Our team then delivered the required 10 day notification to lake shore residents and the University of
Washington facilities that border the treatment area.
The first Sonar PR treatment was made on May 24th throughout the day. We deployed two treatment
vessels and one support vessel to mobilize herbicide from the launch facilities away from the project
site. Each treatment vessel was equipped with RAVEN precision application guidance systems. These
computers contain the treatment area boundaries and plot the course and swath width of the
treatment path the vessel travels. At the end of each swath or pass, the system recalibrated and
provides steering and visual ques to the applicator to insure accurate and complete aerial coverage
throughout the mission. Additional treatments were made as follows.
Date Treatment performed
May 24th First Sonar PR herbicide application
June 14th Second Sonar PR herbicide application
July 19th Third Sonar PR herbicide application
July 25th First glyphosate treatment White Water Lily
July 29th Fourth Sonar PR treatment
August 16th Second glyphosate treatment White Water Lily
At approximately two week intervals, water samples were collected from the treatment areas and
analyzed for fluridone herbicide levels. This information was used to schedule successive treatments
with respect to time, dose and location of dose.
LegendSonar PR Application Zone
SUBA Implementation of IAVMP PlanSonar PR Herbicide Treatment Area
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At the conclusion of the summer, our biologists mobilized mapping vessels back to the lake to review
conditions. Sonar herbicide is a very slow acting technology. The plants take from four to six weeks to
show injury and decline from there over an additional six or more weeks. Observations made on
treatment and sampling trips to the zone showed the normal progression and good herbicide activity.
The mapping effort sampled transects and points throughout the lake and maps were created for
analysis and presentation.
Results and observations
The attached map provides an overview of the control achieved using the Sonar PR strategy selected as
the preferred option by the SUBA board. Overall, Eurasian Milfoil control was excellent. The large
monoculture stands on the western portion of the bay have been removed. This area encompasses
more than 75 percent of the surface area of the treatment zone.
We also mapped two additional conditions observed.
We noted areas that had very sparse growth of Eurasian Milfoil present scattered through the littoral
area. These plants showed Sonar herbicide injury symptoms and may well over the winter continue to
decline.
We also noted one area near the ship canal channel that showed scattered growth of Eurasian milfoil
remaining that we mapped as moderate. This region exhibited significant decline in Eurasian Milfoil, but
there was a slightly higher density of scattered plants remaining within this polygon. The plants here
also showed evidence of Sonar herbicide injury and these may also continue to decline. It is probable
that water exchange in this area was higher than throughout the more enclosed portions of the bay and
perhaps doses received were a bit less. This area can be targeted again as necessary and as the budget
allows.
The White Water Lily control work focused on targeting the first 20‐30 feet of the outside edge of these
communities. The water lily populations were well beyond the areas mapped by Herrera and even
beyond those areas displayed in the aerial imagery used as a backdrop for this project. This image data
is a few years old. The results of this treatment were excellent. Areas adjacent to the University canoe
rental facility were cleared of this noxious weed growth. The access lanes between the Stadium docks
and the Crew House were expanded in terms of open water as were lanes moving to open water. We
targeted this growth along the communities developed shoreline as well. The plants treated this year
will not return and we will continue to reduce these communities in future years as directed by the
IAVMP.
Native aquatic weed growth remains present throughout the bay. In many cases this is a beneficial
development. Native aquatic plants generally do not interfere with aquatic habitat values as invasive
species such as Eurasian Milfoil. Many of these species are not as susceptible as Eurasian Milfoil to
Sonar and in the context of restoration that is a good thing. Dense native aquatic plant growth can
however impact beneficial uses in closed areas such as shorelines, docks, swimming beaches, access
channels.
Legend% E. Milfoil Plants
Sparce E. Milfoil injured
controlledmilfoil
Moderate E. Milfoil injured
SUBA Implementation of IAVMP PlanSeptember Post Treatment Analysis
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The objective of the IAVMP as written and implemented in Year One is stated as follows “The primary
goal of the Submerged Plant Control Plan is the suppression of Eurasian watermilfoil with a secondary
goal of suppressing potential future colonization of Brazilian Elodea populations. Suppression in this
case means limiting plant growth and density to a population that does not impede recreation or
present a swimming safety risk” (page 35, SUBA IAVMP). The plan directs that Sonar aquatic herbicide
(active ingredient fluridone) be applied.
This objective was met by the Year One treatment program. Eurasian Milfoil has been removed from
over 80 percent of the treatment area. Small scattered zones comprising less than 20 percent of the
area treated have scattered sparse and moderate Eurasian Milfoil plants present that at the end of 2012
exhibited herbicide injury symptoms. It is probable that many of these will continue to decline.
As is often the case, when one issue is addressed, secondary problems can develop. This is why a
document like the IAVMP should be reviewed and updated from time to time as necessary.
During the course of the summer of 2012, Sonar herbicide did an excellent job of suppressing and
removing Eurasian Milfoil. That was the objective of the plan for year one. Eurasian Milfoil is very
sensitive to Sonar herbicide and that is the primary reason Save Union Bay Association’s consultant
selected this as the primary management tool in year one. The plan also assumes that treatments in
Year two targeting Eurasian Milfoil and Brazilian Elodea would be necessary and should be budgeted for
at a level of control at $46,000.00 (page 40, SUBA IAVMP).
During the summer of 2012, many of the shoreline residents, especially those on the eastern half of the
Union Bay shoreline experienced good milfoil control, but a mix of aquatic plants that are resistant to
Sonar herbicide continued to interfere with beneficial uses such as recreation and swimmer safety. As
such it is necessary to revisit the objectives of the IAVMP and the control options available.
While Sonar herbicide is not the ideal product to target the noxious aquatic weed growth in these areas
(Curly Leaf Pondweed, Brazilian Elodea etc.) in a shoreline treatment scenario, there are herbicide tools
that will more effectively target this growth in smaller shoreline type treatments.
One of the primary contact herbicides that are very effective on all of the species present in this zone
has a fish timing window as required by the Washington Department of Ecology Permit. Diquat would
play an important role but it cannot be applied until the time window opens on July 15th. This timing
window is in place to avoid exposure of migrating salmon to the herbicide. Diquat can be applied after
July 15th. Renovate OTF granular herbicide has a potential role in areas where Eurasian Milfoil are
present. This herbicide can be used in smaller treatment zones than Sonar because it has a short
contact exposure time requirement. There is no fish timing window for Renovate and it can be used
earlier in the summer. Renovate OTF is selective however and target specific for Eurasian Milfoil. It
does not have activity on species other than Eurasian Milfoil, and much of the shoreline area are
impacted by other noxious weed species. Clearcast is another aquatic herbicide that might have a good
fit. This product has no fish timing window and can be applied earlier in the summer than July 15th. It is
relatively expensive compared to Diquat however.
Legend2013 First Priority Treatment Zone
2013 Second Priority Treatment Zone
% E. Milfoil Plants
Sparce E. Milfoil injured
WW Treatment Zone
SUBA Implementation of IAVMP Plan2013 Projected Treatment Areas and Priority
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The IAVMP direction should be expanded to focus on these other species impacting the beneficial uses
such as recreation and swimmer safety in the near shore environment.
It is also not known which stakeholders will continue to fund the implementation of the IAVMP. The
Save Union Bay Association has funding available and has the capability to raise additional funds from
the shoreline community provided the plan addresses the remaining issues in the near shore
environment. Other stakeholders such as the Washington DNR and the University of Washington may
also participate at some level with continued funding.
Suggested Plan for 2013
Given the unknown funding makeup at this time, we suggest the following approach for 2013. The
primary objective in the IAVMP should be amended to include suppression of other noxious aquatic
weed growth in the high use areas along the shoreline. The program should be divided into a primary
control zone based on one expectation of funding from SUBA members and secondary control zones
should other stakeholders step forward to assist in the continued implementation of the plan. The
following proposed cost table assumes management of 25 acres in Priority Zone One on the attached
map. This area would be surveyed, targeted early in the summer with Renovate OTF or Clearcast based
on plant species make up, and treated a second time with Diquat herbicide at the point the fish timing
window expires.
Table 1, Estimated Costs for implementation of Union Bay IAVMP for 2013
Task Estimated Cost
Water Lily Glyphosate control (4 acres per year)
$2.000.00
Water Lily Glyphosate follow‐up Treatment $1,000.00
First Priority Treatment Zone Clearcast or OTF 25 acres $15,500.00
First Priority Treatment Zone Diquat treatment 25 acres $8,750.00
Ecology permit required public notification and posting, and permit renewal fee to Ecology
$1,500.00
Herbicide monitoring and NPDES WQ sampling compliance $1,500.00
Survey work First Priority Treatment Zone pre and post treatment $2,500.00
Estimated Costs for this level of management for 2013 $32,750.00 plus tax
This budget can be modified to provide additional treatment as stakeholders agree to fund