Vegetation Management Plan Curlyleaf Pondweed Control What is - - PowerPoint PPT Presentation

East Okoboji Lake Aquatic Vegetation Management Plan

Curlyleaf Pondweed Control

What is Curlyleaf Pondweed?

• Non-native submersed, rooted aquatic plant
• Introduced in the mid 1800’s
• First found in Iowa in 1944, IGL’s in the 1950’s
• Widespread - occurring in 48 states
• Adapted to cool water
• Germinates in the fall and begins growth under

ice

• Dies back (senecense) in late June to early July
• Rapid release of nutrients can cause other issues

Curlyleaf Pondweed (Potamogeton crispus)

2015 Curlyleaf Growth

• Last high growth years were in late 80’s
• Regional event in 2015
• Curlyleaf was present all over the IGL’s
• Approximately 600 acres – Narrows to north
• Navigation and access issues
• Future growth is highly unpredictable

Factors influencing growth

• Ice duration
• Snow cover
• Turion density
• Water levels

One of the shortest on record Little snow cover Moderate turion density Low water levels – 2 years

Aquatic Plant Management Plan

• Community led with DNR guidance
• Identifies the problem
• Affirms the importance of aquatic plants

– Balance aquatic habitat with lake use

• Identifies options and a course of action
• Identifies funding partners and lead entities

– Contracting services – Permitting

Importance of Aquatic Plants

• Provide habitat for fish and wildlife
• Help to stabilize bottom sediments and keep the

lakes clear

• Absorb wind and wave energy
• Act as baffles to settle out sediments
• Utilize nutrients otherwise used by algae or

cyanobacteria

• High diversity of plants is a sign of a health lake

Curlyleaf Pondweed Control and Challenges

• Iowa and other states have invested in

curlyleaf control and eradication research

– Whole lake herbicide treatments – Spot treatments to control nuisance areas – Mechanical cutting

• Some success at diminishing turion levels with

regular whole lake herbicide treatments

– Very expensive – Other consequences

Curlyleaf Pondweed Control and Challenges

• Mechanical cutting or raking

– 3 to 4 inches of growth per day – Regular cutting over small areas is best – Allowed by law for riparian landowners with docks – Disposal of plants can be problematic

• Herbicide treatments

– Whole lake or large bay treatments are expensive – Early season low-dose applications are effective and target

• nly curlyleaf pondweed

– Pesticide concerns / public perception – Pesticide application by private citizens to public waters is not allowed – Pesticide treatments are needed yearly if curlyleaf persists

2016 Proposal

• Riparian landowners can mechanically remove

plants (IAC 571, Chapter 54)

• Early season low-dose endothall application

– Water temps between 50 and 60 degrees

• 100 ft wide travel lane, 50 – 100 ft from shore

– Provides travel lanes for boats to move south – Minimizes treatment area (cost savings) – Approximately 65 acres of treatment – Commercial application costs - $250-350/acre

Endothall (dipotassium salt of endothall)

• Common brand names are Hydrothol or

Aquathol K

• 600 ft buffer around drinking water intakes
• Waters may be used for swimming, fishing,

and irrigation immediately after treatment

• Several studies show no adverse impacts to

fish or other aquatic organisms

• Half life is 5 days

Funding

• DNR/State

– Aquatic Invasive Species Program

• Boat registration funds

– Lake Restoration Program

• Legislative appropriation

– Fish and Game Trust Fund

• Hunters and anglers

– Marine Fuel Tax

• 0.9% of motor fuel tax
• Local Funds
• Over 240 private docks

Blackhawk Lake

• Lake access - 62 acre treatment for 2016
• Commercial applicator using endothall

– Approximately $19,000 ($306 / acre) – Responsible for permitting and label requirements

• Funding

– City of Lakeview - $10,000 and contracting – Lake protective association - $3,000 – Sac County - $6,000

• Vegetation harvester - $15,000/year

– $5,000 per partner

• Iowa DNR – Active lake restoration project with several

hundred thousand dollars invested in watershed and in-lake management efforts

Steps forward

• Identification and commitment from partners
• Finalize the management plan and set

investment level (# of acres to be treated)

• Initiate contracting and permitting
• Application of herbicide in mid to late April