Okanogan County Integrated Aquatic Vegetation Management Plan

561 Pages·2014·24.67 MB·English

by  Anna Lyon

OKANOGAN COUNTY
INTEGRATED AQUATIC VEGETATION
MANAGEMENT PLAN
Prepared by OCNWCB
Contributions by:
WDFW
Bureau of Reclamation
USFS
Okanogan Conservation District
Okanogan County Integrated Aquatic Vegetation Management Plan
Table of Contents
Executive Summary ............................................................................................................................................................... 1
Problem Statement ................................................................................................................................................................ 2
Community Involvement ..................................................................................................................................................... 3
History…………………… ............................................................................................................................................. 3
Community Commitment ...................................................................................................................................... 5
Public Consensus ...................................................................................................................................................... 5
Continuing Community Education .................................................................................................................... 5
Watershed and Waterbody Characteristics ................................................................................................................. 6
Watershed Characteristics.................................................................................................................................... 6
Waterbody Characteristics ................................................................................................................................... 7
Characterization of Noxious Aquatic Plants in Okanogan County ..................................................... 12
Noxious Aquatic Weeds in Okanogan County ............................................................................................ 13
Class A Noxious Weeds ....................................................................................................................................... 14
Class B Noxious Weeds ....................................................................................................................................... 15
Class C Noxious Weeds ........................................................................................................................................ 20
Aquatic Plant Control Alternatives ............................................................................................................................... 22
Aquatic Herbicides ................................................................................................................................................ 23
Manual Methods .................................................................................................................................................... 26
Bottom Barriers ..................................................................................................................................................... 28
Diver Dredging ....................................................................................................................................................... 29
Biological Control .................................................................................................................................................. 30
Mechanical-Harvesting and Rotovation ....................................................................................................... 31
Conclusion .............................................................................................................................................................................. 34
Okanogan County Integrated Aquatic Vegetation Management Plan
Appendices:
A: 2014 Survey Report
B: Columbia River Survey
C: Waterbodies
Osoyoos Lake
Pearrygen Lake
Omak Lake
Alta Lake
Blue Lake
Buffalo Lake
Chopaka Lake
Connors Lake
Conconully Reservoir
Conconully (Salmon) Lake
Fish Lake
Forde Lake
Leader Lake
Palmer Lake
Patterson Lake
Pearrygin Lake
Sidley Lake
Spectacle Lake
Whitestone Lake
Okanogan County Integrated Aquatic Vegetation Management Plan
D: Washington Rare Plants
E: Washington State High-Quality or Rare Plants
F: Washington State Species of Concern List
G: Best Management Practices
H: Okanogan Planning
I: Bureau History in Okanogan
Okanogan County Integrated Aquatic Vegetation Management Plan
EXECUTIVE SUMMARY
Aquatic noxious weeds are a detriment to the health and water quality of the lakes and rivers in
Okanogan County. This plan addresses these known infestations of aquatic noxious weeds and outlines
control options for noted species. It will also lay a foundation to control as yet unknown infestations of
new aquatic noxious weeds. Control options will vary by waterbody, local needs, and funding.
A 2014 comprehensive survey of the Okanogan, Similkameen, Methow and Columbia Rivers as well as
several priority lakes with high levels of public access will serve as baseline data for monitoring and
control activities as needed, or desired, to mitigate the impact of invasive vegetation in or adjacent to our
waters. Lakes included in the survey are Alta, Chopaka, Conconully Reservoir, Leader, Omak, Palmer,
Patterson, Pearrygin, Salmon, Sidley and Whitestone. DNR (Dept. of Natural Resources), Okanogan
Conservation District, OCNWCB and DOE (Dept. of Ecology) provided funding for these surveys. Both
Spectacle and Osoyoos have been surveyed (2010 – 2013) recently and treatments have begun.
Further surveys must take place for secondary lakes, those with less public access or waters unsuitable
for vegetative growth excepting the riparian zone surrounding the lake. Funding will continue to be
sought for these additional surveys. Partners in the Okanogan County Coordinated Weed Management
area will continue to seek funding to survey waters within their individual jurisdictions. These surveys,
and the data collected will be incorporated into this document.
Eurasian watermilfoil (Myriophyllum spicatum or E. milfoil) is a commonly found, submersed aquatic
noxious weed that proliferates to form dense mats of vegetation in the littoral zone of lakes and
reservoirs. It reproduces naturally by seed and fragmentation, with primary reproduction from fragments
that “hitch-hike” on boat trailers from one lake to another. E. milfoil is present in many of the lakes and
rivers of Okanogan County.
E. Milfoil can degrade the ecological integrity of a water body in just a few growing seasons. Dense
stands of milfoil crowd out native aquatic vegetation, which in turn alters predator-prey relationships
among fish and other aquatic animals. E. Milfoil can also reduce dissolved oxygen – first by inhibiting
water mixing in areas where it grows, and then as oxygen is consumed by bacteria during decomposition
of dead plant material. Decomposition of M. spicatum also increases existing nutrient levels which can
contribute to increased algal growth and related water quality problems. Further, dense mats of M.
spicatum can increase the water temperature by absorbing sunlight, create mosquito breeding areas,
and negatively affect recreational activities such as swimming, fishing, and boating.
Other submersed and emergent aquatic plant species can be equally detrimental to our waters, and
many are state listed noxious weeds. Increasing awareness of the importance of water quality and the
negative impacts that noxious weeds can have to those resources has necessitated that Okanogan
County devise an Integrated Aquatic Vegetation Management Plan (IAVMP). Because of the complexity
of this document and that it is intended to provide information and options for many individual waters, all
the waters covered under the initial survey are listed separately along with pertinent information.
Additional waters will be added as supplemental data as surveys are completed. All information obtained
for this plan will be housed at the OCNWCB office, currently at RM 102 of the County Courthouse.
This Integrated Aquatic Vegetation Management Plan (IAVMP) is a planning document developed to
ensure that the best available information about the waterbodies and the watershed are utilized prior to
initiating control efforts. Members of the county and various State and Federal agencies have worked
together to develop this IAVMP and ensure a comprehensive approach. To tackle the difficult task of
Okanogan County Integrated Aquatic Vegetation Management Plan 1
generating community concern and educate regarding appropriate action for an environmental issue, a
core group of partners – all collaborators with the Okanogan County Coordinated Weed Management
Area have formed a Steering Committee.

Through their work, the Steering Committee will educate the wider community about the problem, and
inspire them to contribute feedback about potential treatment options. The Steering Committee
ultimately agreed upon an integrated treatment strategy, which includes a combination of chemical, bio
control, and manual, mechanical, and cultural control methods as appropriate for individual waterbodies
within Okanogan County and under various jurisdictions. While there is concern over mechanical
methods such as harvesting or rototilling, they are not a first option of control and other methods will
have preference.

This plan presents lake and watershed characteristics, details of the aquatic weed problems at individual
waterbodies, the process for gaining community involvement, discussion of control alternatives, and
recommendations for initial and ongoing control of noxious aquatic weeds threatening those
waterbodies.

PROBLEM STATEMENT

Okanogan County has a plethora of lakes and rivers, which are home to native plant and animal species.
With the exception of Osoyoos and Spectacle lakes, there has not been a consistent comprehensive
survey of our waterbodies in recent history. The Dept. of Ecology maintains an amount of data
pertaining to many of our lakes, but inconsistent survey schedule and lack of historical GPS/GIS data
does not allow for needed monitoring or control of these sites with invasive vegetation. While many of
these waters are considered waters of the state, Washington State does not have the resources
necessary to consistently survey, monitor nor control invasive noxious weeds within these waters and the
onus of that effort falls to local landowners. DOE does partner in these efforts through Planning and
Implementation grants, available as funding allows.

At this time, there is no readily accessible resource in Okanogan County for these landowners to go to as
they seek answers regarding aquatic noxious weed identification and biology, viable control options, or
permitting processes needed for control efforts in aquatic situations. This document is meant to remedy
the situation and will be available through DOE, our CWMA partners, OCNWCB website
(www.okanogancounty.org/nw), or at the Noxious Weed Office.

Okanogan County relies heavily on agriculture and tourism as economic drivers. Lakes and rivers
infested with noxious weeds are not conducive to optimal recreational uses and can be considered a
safety hazard. In addition, these infested waters reduce agricultural irrigation practices, further reducing
our economic viability.

Due to prolific growth of several species of dense, invasive aquatic noxious weeds, our waterbodies are
in danger of losing their aesthetic beauty, wildlife habitat, and recreational attributes as well as potentially
decreasing the profitability of agricultural production. If left untreated, the most common of these noxious
weeds, Eurasian water milfoil (Myriophyllum spicatum), will further displace native aquatic vegetation,
preventing most recreational uses and eliminating badly needed wildlife habitat. As Engle (Engle 1987)
and Newroth (Newroth 1985) point out, there are negative effects for sport fish species such as Large
Mouth Bass and Salmonids via reduced spawning success. More specifically, Milfoil can reduce water
quality via a number of mechanisms, including increased nutrient loadings; reduce dissolved oxygen and
changes in water temperature (Bates et al. 1985; Madsen 1997). Increasing development in the county
is likely to increase the number of people using our lakes and rivers in coming years, which accelerates
the magnitude of the loss of beneficial uses to the community.
Okanogan County Integrated Aquatic Vegetation Management Plan 2
The shallow shoreline areas of our waterbodies provide an excellent habitat for aquatic plants and
wildlife. Aggressive, non-native species such as Purple loosestrife and Yellow flag iris have invaded
several waterbodies and are colonizing much of the near-shore aquatic habitat.
Milfoil is the most significant submersed invasive threat at this time, but other noxious weeds have also
invaded our waters. These include Fragrant water lily (Nymphaea odorata), Purple loosestrife (Lythrum
salicaria), Curlyleaf pondweed (Potamogeton crispus) and Yellow flag iris (Iris pseudacorus). All of these
species are considered noxious weeds as listed in WAC 16-750. None of the native aquatic plants in the
system are a management issue at this time. The native plants provide important benefits to the aquatic
system and are not impeding any of the recreational uses of the lake. Removing the noxious invaders
will reduce the degradation of the system and allow the dynamic natural equilibrium to be re-established.
Unfortunately, these invasive plants concentrate in the near shore zone, which is also that portion of the
lake that is valued and utilized most by lake residents, visitors and our agricultural communities. Dense
weed growth poses a threat to swimmers, and the portions of the waters where people can fish are
shrinking. E. Milfoil, Curly leaf pondweed and Fragrant water lilies foul fishing gear, motors, and oars. It
is no longer possible to troll through large portions of area lakes. Irrigation from these waters becomes
unpredictable and potentially hazardous when removing aquatic vegetation from intake valves.
As a group these invasive plants:
 Pose a safety hazard to swimmers and boaters by entanglement
 Snag fishing lines and hooks, eventually preventing shoreline fishing
 Crowd out native plants, creating monocultures lacking in biodiversity
 Significantly reduce fish and wildlife habitat, thereby weakening the local ecosystem as well as
degrading wildlife and wildlife viewing opportunities
 Pose a threat to adjoining ecosystems
 Impact oxygen levels
 Threaten a re-emerging Sockeye salmon run
 Pose a threat to the profitability of agriculture
Immediate action is necessary to control Eurasian water milfoil and other invasive aquatic weeds. If left
unchecked, our waters will soon become heavily infested, severely degrading our waters ecosystems
and making the non-native vegetation even harder to eradicate and causing significant impact
downstream.
COMMUNITY INVOLVEMENT
History
Okanogan County residents have typically performed their own weed control by hand pulling, chemical
applications, plastic barriers or bio-control. When it came to aquatic or shoreline weeds, these control
actions have been individually performed, often without training, aquatic labeled herbicides, or necessary
permits. If aquatic herbicides were used, they were purchased from internet distributors and applied in
the dark of night. However, things change and in this case, county residents drove the change.
Since 2006, residents and recreationists have expressed concern regarding the increasing infestations of
aquatic weeds in our water bodies and the limited opportunities for safe recreation. This concern
prompted OCNWCB to actively engage in aquatic noxious weed education and control.
Okanogan County Integrated Aquatic Vegetation Management Plan 3
In 2008, after repeated appeals from Palmer Lake Area Residents Association (PLARA) for assistance in
controlling milfoil infestations, OCNWCB applied for and received coverage under the NPDES Permit
(National Pollutant Discharge Elimination System and State Water Discharge General Permit #
WAG993000) held by Washington Dept. of Ecology (DOE). PLARA members were actively involved and
paid for control costs with assistance from Bureau of Land Management, which owns the boat launch
and water access site at the south end of the lake. Several meetings were held with landowners around
the lake and an education process began for both PLARA and OCNWCB.

At this time, we investigated several control options for invasive aquatic vegetation, including bio controls
and benthic barriers. We began to provide information about milfoil on our Weekly Radio Report and
encouraging water users to take extra caution when entering lakes infested with Eurasian watermilfoil.

Lake Osoyoos residents also began to notice an increase in milfoil and approached OCNWCB for
assistance and education. In 2010, OCNWCB added Lake Osoyoos to the DOE Permit. Because of the
joint border with Canada running through the lake, and concerns from Canada regarding the use of
herbicides and potential drift, a voluntary buffer was established at 1300’ south of the border. It was
agreed that there would be no herbicide use within the buffer and the Lake Osoyoos Association (LOA)
would work with the Okanagan Basin Water Board (OBWB) to potentially allow for use of their harvester
within the buffer area. LOA and OCNWCB applied for and received a Planning grant from DOE and
began an educational campaign that led to further milfoil related radio reports as well as a brochure and
handout regarding identification and detailing “Clean, Drain, Dry” principles. LOA has had an aggressive
education campaign at local boat launches and has spent at least one day every weekend during boat
season distributing handouts and talking to members and visitors about milfoil control, invasive species,
and “Clean, Drain, Dry”.

In 2011, OCNWCB worked with other Weed Boards and State and Federal agencies to create the
International Control of Invasive Aquatic Vegetation for the Upper Columbia River System Cooperative
Weed Management Area (CWMA). This CWMA was established as a means of communication between
the cooperators. An annual meeting occurs to discuss issues and provide support in education and
control efforts. Individual agencies have been working independently and often repeating common
mistakes or “re-inventing” control plans and methods. By communicating and working together, we can
increase the effectiveness of both our education and our control efforts.

In 2013, Spectacle Lake was added to the Permit, with the first aquatic treatment occurring in 2014.
Spectacle Lake is managed by Whitestone Irrigation District and is subject to water drawdowns to
provide irrigation water to surrounding orchards under Global Gap standards. With three resorts and
several private landowners sharing the shoreline, public pressure is high to restore water quality and
recreation. While originally there was not a formal organization to drive control efforts on the lake, the
Spectacle Lake Association was formed and formalized through Washington State.

At this time, Salmon Lake (Upper Conconully) is also seeking milfoil control. This Lake is under Bureau
of Reclamation jurisdiction. Conconully Lake is also expressing interest in implementing control
measures. A survey has been completed of the lower Okanogan and the Columbia River from the
Canadian Border to Rock Island Dam. The survey, funded by CWMA partner DNR, crossed many
jurisdictions, involved multiple partners and required high levels of cooperation. An additional survey,
performed by Okanogan Conservation District and funded by DOE, covered the upper Okanogan,
Methow, and Similkameen rivers as well as the lakes originally covered in this document. We expect
further lakes to express interest in controlling aquatic weeds as awareness continues to increase and
additional lakes are surveyed.

Okanogan County Integrated Aquatic Vegetation Management Plan 4
Community commitment
OCNWCB has maintained an aggressive terrestrial noxious weed program for many years and the
landowners and managers within the county have shown their dedication to weed control efforts. In
many cases they have gone beyond the requirements of RCW 17.10 and instigated control efforts on
non-mandatory control species and worked across property boundaries and jurisdictions to educate and
assist others in developing and implementing a control plan. We have found this same dedication when
dealing with the lakes currently covered by the permit and expect it to be consistent throughout the
county.
OCNWCB currently holds the permit, through DOE, for Palmer, Osoyoos and Spectacle Lakes. We are
committed to assisting in integrated control efforts by maintaining the permit for these lakes. The
communities surrounding these lakes have demonstrated their concern regarding the increasing
infestations of Eurasian watermilfoil and other non-native weeds. They have committed time and
resources to performing survey, control and monitoring efforts as well as educating neighbors and
visitors about the negative impact of aquatic noxious weeds.
The option to add additional lakes or waterways for invasive aquatic vegetation will be available upon
request by shore owners, lake associations, or control requirements mandated by the Washington State
Noxious Weed Law, RCW 17.10.
Public Consensus
The growing amount of Eurasian watermilfoil and other aquatic noxious or nuisance weeds has caused
an increase of public awareness that control efforts must occur to ensure recreational safety, continued
agricultural usage, habitat for native species, and water quality. We expect that control efforts will occur
and shoreline owners and adjacent communities will work together to mitigate the impacts of noxious
weeds in their waters.
However, with the variety of lakes and waterbodies involved in this plan, we do not expect complete
agreement for any preferred control option and will work to incorporate a specific plan that fits the needs
of individual waterbodies.
Continuing Community Education
OCNWCB will offer the means by which the community will receive ongoing education. To ensure that
community education is consistent with best available science and water quality standards, OCNWCB
will continually educate themselves regarding aquatic weed issues by maintaining contact with aquatic
commercial applicators, Dept. of Ecology, Washington State Noxious Weed Control Board and others as
circumstances dictate.
Pertinent information will be distributed through community meetings. Individual waterbodies will be
surveyed and baseline data acquired regarding the noxious weeds present, then we can focus education
efforts to address the issues. Each lake will receive information regarding IPM options and control
methods. Discussions will establish which preferred method would be more effective in their individual
lake.
Watershed mailings will occur when distribution of a species is widespread, such as E. milfoil. OCNWCB
has been very successful in distributing educational handouts through USPS Every Door Direct Mailings.
Utilizing such a method will enable us to reach more people possibly affected by water quality issues
than just those along the shoreline. Previous distributions have been kept and displayed by residents
throughout the growing season.
Okanogan County Integrated Aquatic Vegetation Management Plan 5
KOMW is a local radio station that works with OCNWCB to air a weekly educational segment regarding
noxious weed issues. This enables the Weed Office to reach 13,000 listeners each week. E. Milfoil
segments have aired repeatedly, already increasing awareness and propensity to action.

Aquatic noxious weed brochures and identification cards will be available and widely distributed to raise
awareness among individual landowners of potential non-native invasive plants. A better-educated
community of residents and lake-users will be more likely to identify and report noxious aquatic weeds
and other potential problems. These educational materials will also be available through area
businesses that support recreational opportunities on the water. DOE and LOA have established “Clean,
Drain, Dry” handouts which gives users direction and establishes the need to protect our waters.
OCNWCB has created an E. Milfoil brochure which assists with identification and promotes “Clean,
Drain, Dry” principles. Additional handouts will be created detailing species that we know to be present
in the county and those known to be near and highly aggressive. Educating community members and
other water users will illuminate the relationship between human behaviors and water quality. Each lake
resident will be provided information on how to reduce the amount of pollutants entering the lake from
their property. Property owners with lakeside lots will receive information on lake-friendly landscaping,
subsequently ensuring a healthier lake environment.

Establishment of signs depicting aquatic invasive species will inform lake-users of the presence/absence
of noxious aquatic weeds, how to prevent their spreading them from lake to lake, and promote “Clean,
Drain, Dry” protocols. Many public launches currently have signage, but often they are dated and do not
engage a person to take action regarding noxious weeds or other invasive species. These signs need to
be updated and signs must be posted at all public launches to increase awareness and have a
consistent message.

Volunteers (community members on individual waterbodies) will undergo identification training of aquatic
noxious weeds, enabling them to provide support to continuing control efforts through surveying and
monitoring activities. These volunteers are established on Osoyoos and Spectacle and are providing
valuable information on weed densities, locations, and water quality.

OCNWCB continues to provide education regarding aquatic noxious weeds and with the increased
aquatic education and resulting public awareness of aquatic weeds and associated issues, we expect
further lakes to come forward and discuss their particular aquatic noxious weed issues.

WATERSHED AND WATERBODY CHARACTERISTICS
Watershed Characteristics

The Okanogan River Watershed encompasses about 2,100 square miles in Washington State. This
watershed extends north and south from the Canadian border to the Columbia River. The physical
northern boundary of the watershed is actually in the Canadian province of British Columbia where
another approximately 6,000 square miles is located. Mean precipitation over the Okanogan River
Watershed is 15 inches.

The Okanogan River flows through Osoyoos Lake, which extends across the international boundary, and
continues southward to empty into the Columbia River near Brewster. However, an even greater inflow
from Canada is from the Okanogan's major tributary, the Similkameen River. The Similkameen crosses
the border west of the Okanogan and enters the Okanogan River near the south end of Osoyoos Lake.
About 2.1 million acre-feet of water enters the watershed from Canada as streamflow; about 75 percent
of this amount is from the Similkameen River. The outflow from the watershed at Brewster is estimated
to be 2.2 million acre-feet.

Okanogan County Integrated Aquatic Vegetation Management Plan 6