Identification and Control of Common Invasive and Nuisance Vegetation in Stormwater Management Systems

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1 Identification and Control of Common Invasive and Nuisance Vegetation in Stormwater Management Systems J. Wesley Allen Environmental Scientist Territory Leader Restoring Balance. Enhancing Beauty. November 8, 2017

2 When is Management Needed: Q: What is invasive vegetation? A: Any vegetation that is: 1) not native to the ecosystem is growing in and 2) whose introduction causes or is likely to cause economic or environmental harm or harm to human health.

3 When is Management Needed: Q: What is nuisance vegetation? A: Any vegetation that is growing in an area where it is not wanted, or where it affects the aesthetic, ecological, recreational, or functional integrity of the waterbody.

4 Objectives Part 1: Factors Contributing to Excessive Growth Part 2: Types of Nuisance Vegetation Part 3: Management Strategies

5 PART 1: Factors Contributing to Excessive Growth Nutrient Loading Shallow Depths Hot, Dry Weather

6 PART 1: Factors Contributing to Excessive Growth Nutrient Loading Nitrogen and Phosphorus contribute to the growth of nuisance vegetation in the same way that these fertilizers improve the growth of lawns and gardens.

7 PART 1: Factors Contributing to Excessive Growth Shallow Depths The photic zone is the area of a water body where plants can photosynthesize. When the photic zone extends all the way to the bottom of a stormwater management system, the entire water column is an adequate substrate for nuisance plants.

8 PART 1: Factors Contributing to Excessive Growth Hot, Dry Weather Hot weather contributes to lower dissolved oxygen levels, which makes it difficult for aerobic bacteria to consume excess nutrients and break down organic waste. During times of low precipitation, waterbodies do not circulate and can become stagnant.

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10 Submersed Plants Floating Plants Emergent Plants Algae

11 Submersed Plants Grow completely beneath the water surface and depend on the water for support of the plant body; found in Wet stormwater management systems.

12 Submersed Vegetation Hydrilla (Hydrilla verticillata): Exotic; forms dense mats; reproduces by persistent tubers, turions, and fragmentation

13 Submersed Vegetation Brazilian elodea (Egeria densa): Exotic; forms dense mats; reproduces only by fragmentation of male plants

14 Submersed Vegetation Canadian elodea (Elodea canadensis): Native; can be problematic in high nutrient environments; reproduces primarily by fragmentation

15 Submersed Vegetation Eurasian watermilfoil (Myriophyllum spicatum): Exotic; tends to shade out other species; grows up to 20 feet long; winter hardy; reproduces by fragmentation and stolons

16 Submersed Vegetation Curly-leaf pondweed (Potamogeton crispus): Exotic; very tolerant of turbid water; dies off in mid-summer; reproduces primarily by turions

17 Emergent Plants Rooted to the bottom, but extend above the water surface and are self supporting, can grow in water or on the edge of systems; Stormwater Management Wet or Dry systems

18 Emergent Vegetation Cattails (Typha latifolia and T. angustifolia) Native; excellent habitat plant, but VERY invasive; reproduces by rhizomes and seeds

19 Emergent Vegetation Phragmites/Common Reed (Phragmites australis) Exotic; VERY invasive; reproduces by rhizomes and seeds

20 Emergent Vegetation Water primrose (Ludwigia sp.) Exotic; VERY fast growing, sprawling growth habit; showy yellow flowers; reproduces prolifically by seeds

21 Emergent Vegetation Parrotfeather (Myriopyllum aquaticum) Exotic; VERY difficult to control; sprawling growth habit; reproduces by rhizomes and fragmentation

22 Floating Plants Rooted on the bottom with floating leaves, or free-floating; Wet Stormwater Management Systems

23 Floating Plants Watershield (Brasenia schreberi) Native; can grow in water up to 6 feet deep; gelatinous slime on underside of leaf; reproduces by seeds and rhizomes

24 Floating Plants White water lily (Nymphaea odorata) Native; can grow in water up to 5 feet deep; flowers open early in the morning and close mid-day; reproduces by seeds and rhizomes

25 Floating Plants Spatterdock (Nuphar lutea spp.) Native; roots can be up to 6 inches in diameter; half-opened yellow flowers; reproduces by seeds and rhizomes

26 Floating Plants Watermeal (Wolffia spp.) Native; smallest seedbearing plants in the world; reproduce rapidly by budding and can cover the entire surface of a pond within a few weeks

27 Floating Plants Duckweed (Lemna spp.) Native; gets nutrients directly from water column through tiny roots; reproduce rapidly by budding and can cover the entire surface of a pond within a few weeks

28 Algae Simple plants with no vascular tissue; do not produce true roots, leaves, or flowers

29 Algae Filamentous algae (Spyrogyra, Anabaena, Pithophora, etc.) Begins growth on the pond bottom; forms mats that rise to surface; looks like horse hair or scum

30 Algae Planktonic algae (Chlamydomonas, Euglena, Anacystis, etc.) Microscopic floating plants; desirable in moderate amounts (base of food chain); can appear as green water or surface slime

31 Algae Muskgrass (Chara spp.) Branched, multicellular algae often confused with submersed flowering plants; has foul, musky odor and grainy texture

32 PART 3: Integrated Vegetation Management (IVM) Strategies No Action Prevention Mechanical/ Physical Practices Cultural Control Biological Control Herbicides/Algaecides Nutrient Inactivation

33 PART 3: IVM Strategies Mechanical/ Physical Control Mechanical Harvesting

34 PART 3: IVM Strategies Physical Practices Dredging Drawdown Benthic Barriers Shading/Light Attenuation Aeration Clearing

35 PART 3: IVM Strategies Aeration Encourages the growth of beneficial bacteria, which help to utilize excess nutrients and break down decaying organic matter. Discourages thermal stratification and helps ensure adequate oxygen levels throughout the water column. Not an option for all Stormwater Management Systems.

36 PART 3: IVM Strategies Cultural Methods Avoid Excess Fertilizer Use Vegetated Buffers/Beneficial Plantings New Construction Methods Erosion/ Sediment Control

37 PART 3: IVM Strategies Biological Control Beneficial Bacteria and Water Quality Augmentation; Wet Systems Only

38 PART 3: IVM Strategies Herbicide/Algaecide Control Licensing, Insurance, Equipment, Reporting (Consider Hiring a Professional)

39 PART 3: IVM Strategies- Contact Herbicides Fast acting on plant tissue (~7days) Can cause DO depletion if not careful Causes extensive cellular damage, but not roots Usually only provides seasonal control Site-specific Can be species selective Examples: diquat, endothall, flumioxazin

40 PART 3: IVM Strategies- Systemic Herbicides Product is translocated throughout the plant structure Longer contact time needed, but Slower decomposition has less effect on the lake s oxygen regime Often multi-year control of certain species can be achieved Tend to be more species selective Granular formulations useful for site specific or high flow areas Examples: glyphosate, fluridone, 2,4-D, triclopyr

41 PART 3: IVM Strategies- Algaecides Fast Acting and Works on Contact - Different Formulations Work Best for Each Algae Species - Be wary of dissolved oxygen when algae infestation is very bad - May require multiple treatments Granular formulation and liquid formulations Examples: Chelated Copper, Copper Sulfate, and Peroxide Based

42 PART 3: IVM Strategies- Dyes and Covers Mode of Action: Inhibits Light Penetration Advantages: Non-toxic (dyes) Can be very effective Increased aesthetics Disadvantages: Not suitable for large water bodies Covers interfere with water use/aesthetics May increased heat absorption May not control plants in shallow water Reapply due to basin flushing

43 PART 3: IVM Strategies- Nutrient Inactivation Mode of Action: Removes or Binds Nutrients (Phosphorus) from water column or sediment Advantages: Non-toxic Can be very effective Attacks Cause of Problems Disadvantages: Not suitable for all stormwater systems Reapply due to basin flushing/new nutrient loading Requires testing to be applied properly Can be cost prohibitive Most effective on algae Examples: Lanthanum Clay, Aluminum sulfate

44 Please Share Your Takeaways J. Wesley Allen Environmental Scientist Territory Leader solitudelakemanagement.com LAKE November 8, 2017