Looking after Loe Pool

Loe Bar and surrounding countryside from the air

Loe Pool is Cornwall’s largest natural lake and home to a variety of wildlife (Loe means pool in Cornish so we often refer to it as “the Loe”). Like a lot of freshwater lakes it suffers from eutrophication- the process that sees increased nutrient levels in the water causing a change in ecology and algal blooms. As a result, The Loe Pool Forum was founded by The National Trust in 1996 to look at ways of reversing this worrying decline in water quality. This partnership of environmental organisations include Natural England, South West Water and Cornwall Wildlife Trust amongst others.

The main inputs of nutrients to the water were through agricultural run- off and two sewage treatment plants feeding into the Loe. One enormous step forward was the installation of a tertiary treatment plant at South West Water’s sewage treatment works in Helston. This quartered the input of Phosphorous into Loe Pool. To complement this, RNAS Culdrose upgraded their sewage treatment works in 2015 resulting in an 80% drop in Phosphorous input. 

The marsh at Loe Pool, Penrose
The marsh at Loe Pool, Penrose

Farmers surrounding the Loe have also been working hard to reduce their nitrate and phosphate inputs by changing farming practices. Loe Pool and its catchment are within a Nitrate Vulnerable Zone, which means the amount of fertiliser and organic manure spread on the land has been reduced and the time of year that muck spreading happens has been limited to a few months in the summer. This reduces the risk of heavy rainfall washing nutrients off the fields and into the water. 

Pochard on Loe Pool, Penrose
Pochard on Loe Pool, Penrose

Another important aim of the Forum is to encourage partnerships with local universities and colleges to research the ecology and the history of the Loe. Many fascinating student projects have been published in recent years, including a report on whether Helston could have been a port, and a hydrographic survey of the bottom of the Loe. The forum has also commissioned dive surveys to assess the health of underwater plant populations and surveys into the elusive Loe Trout- a subspecies of brown trout that is unique to the Loe. 

Divers conducting a survey of Loe Pool
Divers conducting a survey of Loe Pool, Penrose

Algal blooms in the water started in the 1980s but the last one was in 2006, which shows how the water quality is starting to recover as a result of all these improvements. Otters are spotted in the quieter areas, and we’ve seen starlings come back to roost in the autumn again, so we’re positive about the future of the Loe as a good quality habitat.

A Heron in the woodlands at Penrose
A heron rests in the woodlands at Penrose

To find out more about the Loe Pool Forum and to discover reseach by local universities click here