Invasive Species

The Ozaukee County Planning and Parks Department (Department) conducts invasive vegetation species inventories within Ozaukee County-owned properties, habitat restoration project areas and within right-of-ways of state, county and federal roads to obtain information on invasive species presence and population. The inventories combine systematic field and GPS data acquisition methods to better understand and enhance the Department’s knowledge of invasive plant locations, population levels, treatment methods and success. The inventory’s objective is to accurately locate invasive species populations within natural areas, determine population levels (e.g. density and coverage), prescribe recommended control/treatment, and reassess population locations and infestation levels after several years of on-the-ground control and management. During invasive vegetation species inventories, Department staff also inventory ash tree populations as part of invasive emerald ash borer detection and management.

Between 2016 – 2019, Ozaukee County Planning and Parks Department staff formally inventoried 252 acres of County Park land and detected 29 invasive vegetation species including: amur maple, autumn olive, black locust, bull thistle, Canada thistle, common buckthorn, common burdock, common comfrey, common tansy, common teasel, cut-leaved teasel, Dame’s rocket, emerald ash borer, garlic mustard, glossy buckthorn, honeysuckle (Lonicera spp.), Japanese barberry, Japanese knotweed, lily of the valley, multiflora rose, narrow-leaved cattail, phragmites, purple crown vetch, purple loosestrife, reed canary grass, snowdrop, white sweet clover, wild parsnip and yellow sweet clover. Inventories are ongoing in conjunction with ongoing management activities. 

In 2019, Ozaukee County Planning and Parks Department staff also conducted surveys along the right-of-ways (ROW) of all private, local, state, county and federal roads within Ozaukee County for invasive teasel, Japanese knotweed, phragmites and wild parsnip to add to and update an existing database managed by the Southeastern Wisconsin Invasive Species Consortium, Inc (SEWISC). 

Why You Should Care

If you enjoy being out on the water, hiking in the woods, or enjoying the native wildlife outside; you should be concerned about these "biological bullies". These nonnative species out compete our native species for food, water, and light. This imbalance in the ecosystem can permanently alter the future viability of our native plants and animals.

Types of Invasive Species


  • Curly-Leaf Pondweed
  • Eurasian Water Milfoil
  • Quagga Mussels
  • Round Goby
  • Rusty Crayfish
  • Sea lamprey
  • Zebra Mussels


  • Asian Lady Beetle
  • Buckthorn
  • Emerald Ash Borer
  • Garlic Mustard
  • Gypsy Moth
  • Spotted Knapweed


  • Crown Vetch
  • Japanese Knotweed
  • Phragmites Australis
  • Purple Loosestrife
  • Reed Canary Grass
  • Wild Parsnip