East Okoboji Lake Aquatic Vegetation Management Plan. Curlyleaf Pondweed Control

Transcription

1 East Okoboji Lake Aquatic Vegetation Management Plan Curlyleaf Pondweed Control

2

3 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

4

5 Curlyleaf Pondweed (Potamogeton crispus)

6

7

8

9

10 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

11

12 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

13 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

14 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

15 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

16 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 only 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

17 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, ft from shore Provides travel lanes for boats to move south Minimizes treatment area (cost savings) Approximately 65 acres of treatment Commercial application costs - $ /acre

18

19 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

20 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

21 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

22 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