Identifying Invasive Plants in Stormwater Facilities

Stormwater facilities – including ponds, bioretention cells, bioswales, and infiltration basins – are designed to filter pollutants, slow runoff, and protect waterways. But when invasive plants take hold, these facilities can lose effectiveness and require costly maintenance. Across Maryland, Northern Virginia, Washington, DC, and Delaware, invasive plants threaten both stormwater infrastructure and the health of the Chesapeake Bay.

This guide explains how to identify invasive plants in stormwater facilities, why they’re problematic, and which native alternatives thrive in our region.

Why Invasive Plants Are a Problem for Stormwater Systems

Invasive species spread aggressively and outcompete native plants, disrupting the balance that stormwater best management practices (BMPs) depend on.

Key impacts include:

• Reduced performance and clogged structures
• Increased erosion and slope instability
• Loss of biodiversity and wildlife habitat
• Higher maintenance costs
• Local regulatory restrictions on invasive species

Invasive Plants to Watch in Maryland Stormwater Facilities

Maryland stormwater ponds and bioretention areas often struggle with:

• Phragmites australis (common reed) – creates tall, dense monocultures in wet zones
• Japanese stiltgrass (Microstegium vimineum) – overtakes swales and shaded buffers
• Multiflora rose (Rosa multiflora) – orms thickets that block maintenance access

The Maryland Invasive Species Council lists these and many more plants that threaten stormwater function across the state.

Invasive Plants in Northern Virginia Stormwater Ponds and Bioswales

In Northern Virginia, invasive vines and shrubs are especially common:

• Oriental bittersweet (Celastrus orbiculatus) – smothers trees and structures
• Japanese honeysuckle (Lonicera japonica) – spreads along pond banks and buffers
• Tree of heaven (Ailanthus altissima) – sprouts aggressively and damages infrastructure

The Virginia Department of Conservation and Recreation (DCR) provides invasive plant lists and guidance for landowners.

Invasive Plants Threatening DC Green Infrastructure

Washington, DC has invested heavily in green infrastructure projects like rain gardens and bioswales. Unfortunately, these systems are vulnerable to:

• English ivy (Hedera helix) – a common groundcover that quickly invades facilities
• Porcelainberry (Ampelopsis brevipedunculata) – a fast-growing vine often mistaken for grape
• Japanese knotweed (Fallopia japonica) – spreads by rhizomes and can damage hardscape structures

In urban stormwater sites, invasives not only block water flow but can also compromise engineered soils and designed planting plans.

Invasive Plants in Delaware Stormwater Management Facilities

Delaware’s stormwater ponds and ditches are especially prone to:

• Purple loosestrife (Lythrum salicaria) – produces thousands of seeds and overtakes wetlands
• Japanese stiltgrass – a regional problem in shaded slopes
• Callery pear (Pyrus calleryana) – spreads from landscaping into stormwater buffers

The Delaware Department of Natural Resources and Environmental Control (DNREC) offers best practices for invasive plant removal and native replacement.

Native Plants for Stormwater Facilities in the Chesapeake Bay Region

Replacing invasives with native species not only protects stormwater function but also supports Bay restoration goals.

Wet Edges & Shallow Water

• Blue flag iris (Iris versicolor)
• Pickerelweed (Pontederia cordata)
• Buttonbush (Cephalanthus occidentalis)
• Soft rush (Juncus effusus)

Slopes & Buffer Zones

• Switchgrass (Panicum virgatum)
• Joe-Pye weed (Eutrochium purpureum)
• Winterberry holly (Ilex verticillata)
• Black-eyed Susan (Rudbeckia hirta)

Upland or Drier Zones

• River birch (Betula nigra)
• Red maple (Acer rubrum)
• Eastern red cedar (Juniperus virginiana)
• Common milkweed (Asclepias syriaca)

These native species stabilize soils, filter runoff, and provide food and habitat for pollinators, birds, and other wildlife.

Stormwater Facility Management Tips for Property Owners

• Inspect facilities at least three times per year (spring, summer, fall).
• Remove invasive seedlings early before they spread.
• Replant disturbed soil with fast-growing natives.
• Require contractors to use weed-free seed mixes and mulch.
• Document problem areas and schedule follow-up maintenance.
• Partner with professionals who understand both stormwater regulations and invasive species management.

Conclusion

Stormwater facilities in Maryland, Northern Virginia, DC, and Delaware are vital to protecting the Chesapeake Bay – but invasive plants threaten their effectiveness. By identifying invasives early and replanting with strong native species, property managers can protect water quality, reduce maintenance costs, and improve facility resilience.

👉 Need help with invasive plant control in your stormwater ponds, swales, or bioretention areas? Our team provides inspection, maintenance, and native planting services throughout the Chesapeake Bay region.

📞 Call us at (410) 231-3455 or 💬 Contact us online.