03/09/2026
Ever wondered why Longwater Lake looks a little different lately? 💚
With the long stretch of high temperatures we’ve had, the lake has taken on a distinctly green appearance. It might look unusual, but it’s actually a completely natural response to warm, sunny weather.
🌿 The green colour is caused primarily by an increase in algae, as well as microscopic organisms called cyanobacteria which can cause streak-like green marks in the water. These organisms use sunlight as an energy source to grow, and this growth is boosted when warm, settled water contains specific nutrients such as nitrogen and phosphorus.
🌊 This can result in an algal bloom, where the algae become more concentrated nearer the surface, making the water appear green and cloudy.
🐟 While algae and cyanobacteria are a natural part of the lake’s ecosystem, providing food and oxygen to aquatic organisms and forming an essential part of the food chain, particularly dense algal blooms can negatively affect the water quality and reduce oxygen levels as algae die and decompose.
As temperatures drop, sunlight becomes less intense and water movement increases, conditions generally become less favourable for rapid algal growth. This can allow algae to decline towards lower levels. Rainfall can sometimes slow that process by washing in extra nutrients, so it may take a little while to see a visible change.
Longwater Lake is home to a huge range of wildlife, so our Biodiversity Coordinator team and the experts at Ground Control will be keeping a close eye on things over the coming weeks 👀
