The Effects of Water Diversion and Extraction on Ecosystems and Biodiversity

As our global population increases and climate change takes effect, it is more important than ever for water utilities to consider the impact of water infrastructure on the earth’s ecosystems and biodiversity. Overexploitation of freshwater supplies is having devastating effects on the natural world and is causing our available water supplies to shrink to dangerous levels.

Large dams, aqueducts and canals have been in existence since the Roman times, used to reserve and transport freshwater to settlements. A feat of engineering and architecturally impressive, these monstrous constructions played an essential part in the evolution of our species. Unfortunately, these means of water conservation have had major negative consequences for earth’s ecosystems. By altering the natural course of river water into the sea, entire ecosystems become imbalanced, fish migration is affected, plants are killed, and animals are forced to move out of their natural habitat.

Sedimentation is another major issue. Sediments would normally be carried downstream and out to sea. When these sediments are stopped by a dam, they settle in reservoirs which not only leaves less space for water, but also has knock-on effects for plants, wildlife, and human settlements downstream that rely on the nutrients the sediments supply. Without the natural flow of sediments from upstream, rivers will seek to replenish themselves by eroding riverbeds and banks. This lowers the water table and has a snowball effect on ecosystems. The stagnant reservoir can also affect the chemical composition, dissolved oxygen levels and temperature of the river both up and downstream, wreaking havoc for plant and animal life. 

River flooding is also a natural phenomenon that is vital to river ecosystems. It is instrumental in creating backwater and beach habitats, as well as recycling nutrients. The building of dams stops this natural flooding and therefore inhibits the river from feeding plants and wildlife.

Dams also contribute significantly to greenhouse gas emissions. Recent studies show that the sediment and nutrient flow from rivers drive biological processes far into the oceans, including serving as carbon sinks for atmospheric greenhouse gases.

The construction of large dams has caused the complete disappearance of several bird and fish species and the degradation of forests, wetlands, and coastal deltas. The Colorado River is one of the most heavily developed river systems in the world, with 15 main dams and hundreds more along its tributaries. In the Grand Canyon and in other areas along the Colorado River, many native species have disappeared, including river otters, muskrats, several species of frogs, lizards, and birds.¹ Invasive species of plants have taken over vulnerable parts of the landscape and altered the ecosystems and the landscape in dramatic ways.

Groundwater is our largest freshwater source. Groundwater pumping has caused dramatic changes to our natural landscape. Over-pumping causes the water table to drop, resulting in dried up streams, lakes, wetlands, and land subsidence along rivers – resulting in the destruction of highly productive ecosystems. The steep riverbanks we are used to seeing are a direct cause of groundwater pumping as the drier earth subsides. Naturally shallower riverbanks would support an abundance of plant life and in turn provide food for a variety of invertebrates and mammals.

In coastal areas, over-pumping can cause saltwater to move further inland and contaminate freshwater supplies, which is called saline intrusion. This problem is frequent along parts of the Mediterranean coast, where water demand from tourist resorts is high and available water supplies are low, such as Malta. Parts of both Italy and Spain have faced difficulties with saline intrusion because of overexploitation of groundwater for irrigation purposes.²

Malta and many other countries with low freshwater resources rely heavily on desalination. Desalination plants also pose a considerable threat to the environment. Marine life can suffer immensely from the heavily-salinated wastewater that is pumped back into the oceans and also in the intake process. Desalination also makes a considerable contribution to greenhouse gas emissions as so much energy is needed to process the water.

Protecting our freshwater supplies and the environment go hand in hand. By restoring ecosystems and making our urban areas greener, water utilities around the world can play a huge part in protecting the environment and, in turn, provide safe, sustainable water supplies for the growing population. As more studies reveal the devastating effects of water extraction and diversion on the natural world, water utilities and governing bodies are working hard to keep up with the demand for clean water whilst finding new ways to limit damage to the environment.

The Sacramento-San Joaquin Delta is California’s most crucial water and ecological resource. Providing drinking water for 29 million people, as well as irrigation water for a large agricultural industry, this vast delta has suffered greatly due to the infrastructure. Considering the degradation of this important ecological resource and the impacts of this on the water supply, the Delta Plan, updated in 2019, was put in place to protect and reform the ecosystems and wildlife that exists in the area.

Reducing and reusing wastewater are clearly the most effective ways forward for water utilities. In the UK alone, more than 3 billion gallons of clean water is wasted every single day.³ Repairing infrastructure to prevent leaks, capturing runoff, and restoring natural habitats will all go a long way to helping us prevent so much waste.

By turning to wastewater treatment instead of dam building and groundwater pumping, the environment will benefit in many ways. As well as the obvious benefits, valuable non-renewable resources such as phosphorus can be extracted from the wastewater, providing the water utilities with income, and preventing us from having to mine it from the sea.

Another important change will be opting for green infrastructure instead of grey infrastructure in urban areas. Creating green areas that mimic the natural hydrology cycles such absorbent gardens, green rooftops, and roadside planting that can capture rainfall, would stop useable water from entering the sewage systems, reduce flash floods and ultimately boost the quality and quantity of freshwater supplies for the area. Of course, there are countless other benefits of green infrastructure, for both residents and the environment, including the creation of habitat for wildlife, air quality and mental health.

Changes within the agricultural sector would also make a considerable difference to the amount of water we waste. The sector uses 70% of the world’s freshwater withdrawals, compared with just 8% for household use, although this varies greatly by region globally.⁴ Using drip irrigation, particularly solar-powered drip irrigation, may be the most eco-friendly option for farmers and could make a significant decrease in the amount of wastewater if it was used more widely.

Whilst progress is being made, changing the way we capture water will take time and a lot of investment. So, you may be asking ‘what can we do now as individuals to reduce our water footprint and protect the environment?’

Educating the public on the issues surrounding freshwater supplies can help to alleviate some of the pressure. In richer countries, the amount of water used and wasted by individuals is phenomenal. By making small changes to our daily lives, we can all help in the fight to conserve water whilst protecting our ecosystems and boosting biodiversity. A shift in culture is key if we are to successfully protect our planet and the abundance of life that resides on it. 

Learn more about our Water Solutions for a sustainable future.

¹ National Geographic, Earth's Freshwater
² European Environment Agency, Impacts Due to Over-abstraction
³ Maintain Drains, The UK Is Wasting Billions of Litres of Clean Drinking Water Every Day
⁴ Too Good To Go International, The Water Crisis