Nutrient Pollutants and Water
The main nutrient pollutant is phosphate, it and comes from many things such as cleaning products and fertilisers. Some phosphates are removed at larger treatment works but not at smaller ones or private sewage systems.
Too many phosphates have a negative impact in water. The water becomes nutrient-rich (eutrophication) which leads to an increase in algae, creating algal blooms. This also favours nutrient tolerant plants which can then dominate, changing the natural balance in and around the lake.
Algal blooms take up a lot of oxygen from the water, starving plants and deep-water fish like the Arctic Charr. The decaying plant matter also smothers the bed of the lake impacting on spawning, so numbers will continue to decline. In time, the lake margins will change, the reedbeds will be affected and some invasive non-native species will thrive.
Some algal blooms, such as blue-green algae (cyanobacteria) is harmful to wildlife and pets and it’s these blooms that are a concern in Coniston Water. Not all algal blooms release toxins, nor do they all behave and develop in the same way so it can be difficult without formal testing to tell if the blooms are harmful or not.
Blue-green algae will threaten swimming and other leisure activities on Coniston Water, as has happened on several occasions on Windermere. This will impact on the tourism industry as thousands of people are drawn to the beauty of the lake each year.