Chemicals are currently the main causes of lake pollution around the world. As the world strives to become industrialized chemical wastes are expected to rise. This means that stringent measures are needed to be taken in order to protect the lake environment for future generations.
Source: http://www.conserve-energy-future.com/
Eutrophication is a major problem that arises due to use of fertilizers which are then carried to lakes by rainwater. This increases the concentration of nitrates or phosphates which encourages algae growth. A growth of algae prevents sunlight from reaching other aquatic organisms which then suffocate and die. Bacteria then decompose the dead plants and use up the oxygen in the water rendering it completely lifeless. Source: BBC science
This is Lake Karachay in Russia. It has been ranked among the world's most dangerous and uninhabitable regions. This is due to radioactive waste that has been dumped into the lake by the nearby Mayak nuclear facility. Due to droughts in the area, most of the lakes area has evaporated away to leave a bed of Strontium and Cesium. This makes it extremely hazardous for the local community Source: http://www.dailymail.co.uk/sciencetech/article-2215023/Is-polluted-place-Earth-The-Russian-lake-hour-beach-kill-you.html
Dark oil slicks on Venezuela’s Lake Maracaibo surface has negative impacts on the lake's wetlands, mangroves, beaches and docks. The oil is permeating the fishing nets, coating the garbage in the lake, killing off the local wildlife and driving away residents and tourists.
Located in northwest Venezuela, Lake Maracaibo is the largest lake in South America, covering 12,800 square kilometers. The shoreline and lake bed have recently been the sites of intense petroleum production since the second decade of the 20th century
Source: http://www.ipsnews.net/
The photo shows the proximity of the flower farms to Lake Naivasha in Kenya. The flower industry is one of the country's highest foreign exchange earner but also the main culprit in the pollution of the lake seen in the background. The fertilizer run off from the farms have caused deaths of aquatic life in the lake and the local authorities have tried to tame the pollution by involving all stakeholders like the farmers and local community to try to preserve the lake and its ecosystem and continue with the flower farming in a more sustainable way.
Image source: www.dutchwatersector.com