Know Your Weeds: A Guide to the Most Common Aquatic Weeds in the UK

Aquatic weeds can cause significant problems if left unmanaged - from blocking water flow to damaging habitats and restricting recreational use. Whether you’re managing a private pond, fishing lake, or large watercourse, knowing what you’re dealing with is the first step toward effective control.

At The Aqua Contractor, we specialise in chemical-free, mechanical weed removal across the UK. Below is our guide to some of the most common aquatic weeds we encounter.

1. Duckweed (Lemna minor)

Fast-growing and often underestimated, duckweed can quickly blanket the surface of still or slow-moving water, reducing oxygen levels and blocking sunlight.

How to spot it: Tiny, bright green, floating leaves (1–5mm) that cluster together to form dense mats.

2. Canadian Pondweed (Elodea canadensis)

A submerged invasive species that spreads aggressively, Canadian pondweed is commonly found in rivers, canals, and ponds, where it restricts flow and traps sediment.

How to spot it: Long, slender stems with whorls of 3 (sometimes 4) small, curved leaves.

3. Curled Pondweed (Potamogeton crispus)

This native plant starts growing in early spring and can form dense underwater thickets, especially in still or slow-moving water.

How to spot it: Reddish-green, crinkled leaves attached directly to long stems.

4. Fringed Waterlily (Nymphoides peltata)

Not to be confused with native waterlilies, this invasive species spreads across the surface, shading out native plants and impeding water flow. It is fast-growing and difficult to control once established.

How to spot it: Small, round floating leaves and bright yellow flowers with fringed petals in summer.

5. Bulrush (Typha latifolia and Typha angustifolia)

Often seen at the edges of ponds and lakes, bulrush can become invasive in shallow water, where it spreads rapidly via rhizomes. While it is native and ecologically valuable, it can take over if not managed.

How to spot it: Tall, grass-like stems with distinctive brown, sausage-shaped flower spikes.

Why It Pays to Act Early

Aquatic weeds don’t just look unsightly - they reduce water quality, limit biodiversity, and cause access issues for anglers, boaters, and land managers. Early identification makes it easier to stay in control and can reduce the cost and frequency of intervention.

How We Help

At The Aqua Contractor, we provide:

We work with private landowners, estates, councils, and commercial clients to restore and maintain healthier water bodies across the UK.

If you think your pond, lake, or canal might be affected by aquatic weeds, get in touch with us today to discuss your site and how we can help.