Causes of Water Pollution in Dams and Reservoirs

Water pollution is more than unsightly murky water; it can be extremely harmful to marine life and human health if not managed. Many factors influence water quality, some of which are biological, while others are by our own hand.

Protecting your dam or reservoir starts with understanding the various sources of pollution and their impacts. Once things spiral out of control, regaining optimal water health is challenging but not impossible.

Uncover all you need to know about water pollution in dams and reservoirs, including how effective strategies and equipment can change the trajectory.

Biological Causes of Water Pollution

Living organisms may be natural, but some negatively impact water quality. This often includes depleting oxygen and introducing bad bacteria into aquatic ecosystems.

Organic Matter Decomposition

While important for cycling nutrients, dead plants and animals decompose in large quantities in water, requiring a lot of dissolved oxygen. Algae and bacteria spread more easily when gases like ammonia are released.

Algal Blooms

Algal blooms are the fast spread of algae typically caused by nutrients from organic matter or agricultural runoff. These nutrients essentially fertilise the algae, resulting in it spreading across the dam. Fish and other aquatic life struggle to survive with this oxygen depletion and toxins released by certain algae types.

Bacteria and Disease

Bacteria like salmonella and E. coli can enter dams and reservoirs through animal waste and agricultural runoff, contributing to contaminated water.

Stagnant waters with low oxygen levels, which are customary in dams and reservoirs, exacerbate bacteria problems and are very dangerous for drinking water and marine environments.

Environmental Causes of Water Pollution

Regardless of how you protect your dam or reservoir’s water quality, nature sometimes has other plans. Environmental causes refer to natural events, which some may argue are a byproduct of human activity. 

Agricultural Runoff

Runoff from agricultural land introduces toxic chemicals like pesticides and fertilisers, making it a major contributor to water pollution. When rainfall or irrigation water flows over treated farmlands, it washes the harmful chemicals away and into local waterways.

Erosion

Environmental occurrences, such as especially strong rain and wind, can cause erosion. This is when rocks, soil, sand, etc., are worn away and carried into the water.

When tree or plant roots are removed by landscaping activities, the soil’s structure is compromised, making it more prone to loosening and falling into the water. In addition to causing murky water (making it difficult for sunlight to penetrate and oxygenate aquatic plants), erosion contributes to sedimentation.

Sedimentation

Sediment consists of organic matter like soil or dead plants that settle on the bottom of the water. If untreated, sediment layers can suffocate habitats and the organisms that live in them. Sediment can also slowly release pollutants picked up from elsewhere, providing a continuous source of toxic substances.

Human Causes of Water Pollution

Humans are responsible for much of the water pollution we see today. Whether from large oil spills or improper disposal of toxic waste, the results are severe.

Oil Spills

Oil drilling operations or accidental spills during transport are a few examples of oil pollution in water. When oil spills enter dams from the ocean or from immediate construction, they create surface water pollution that also affects plant and marine life underneath.

Sewage and Wastewater

Sewage treatment plants manage wastewater by removing contaminants before they enter natural water bodies like dams and reservoirs. However, sometimes industrial and municipal wastewater still seeps through.

Sewage nutrients like nitrogen and phosphorus can lead to excessive nutrients and, thus, more algal growth. Pathogens and bacteria pose a serious threat to human and marine life.

Industrial Waste

Industrial sites produce waste from various processes, such as mining and manufacturing. Without proper waste management systems, these pollutants can enter dams and reservoirs, adding to sediment buildup and toxic chemicals.

Stratification of Water 

Stratification is where layers form in a waterbody, with cold, oxygen-depleted water at the bottom and warm water at the top.

Stratification is particularly apparent in tropical conditions native to countries like Australia. Higher temperatures result in organic matter decomposing faster, thus using more oxygen and releasing damaging gases.

Effects of Water Pollution in Dams and Reservoirs

As there are numerous causes of water pollution, the impact it triggers in dams and reservoirs is equally varied.

Contaminated Water

When pollutants gather in water bodies, they degrade water quality, making it dangerous for consumption and daily use. Toxic substances like pesticides and bacteria can seep into the water through agricultural runoff, industrial waste, and sewage.

This contamination makes water treatment more expensive and complicated. If communities lack the resources to manage the issue, they face the risk of waterborne diseases and potential health-related issues. Contaminated water can also not be used for irrigation, as the pathogens spoil the food ecosystem.

Damaged Aquatic Life

Pollution plays a big role in managing aquatic environments. Fish and other organisms suffer greatly from excessive nutrients and low oxygen levels, which results in declining fish populations and species that cannot survive in such conditions.

Additionally, industrial contaminants can gather in aquatic tissues, leading to reproductive issues, poor growth, and increased death rates. Over time, this contamination weakens the entire food chain, impacting biodiversity.

Decreased Water Supply

As sediment builds on the bottom layer of dams, the water capacity and flow are disrupted. When supply demand is high during the summer, dams and reservoirs suffering from water pollution will find it hard to function optimally.

Harmful Gas Emissions

The buildup of decomposing organic material in low-oxygen bodies of water releases gases like methane, one of the strongest greenhouse gases. In addition gases like hydrogen sulphide give off a rotten egg smell, making recreational activities unpleasant.

Methods to Control Dam and Reservoir Water Pollution

Water pollution is a major threat to our dams and reservoirs, so what can be done to fight it? Various methods, ranging from land management to advanced technology, can be used to protect and restore water quality.

Planting Vegetation

Planting trees and plants around dams creates a natural buffer against erosion and runoff. Certain foliage’s deep root systems create a structure that holds soil in place and catches particles before they seep into the water. This natural filtration system significantly reduces sediment and contributes to wildlife habitat.

Waste Management

Managing water contamination in dams reduces pollutants from sources like industrial wastewater and untreated sewage. Optimising sewage treatment facilities is really important as wastewater can breed disease and introduce dangerous bacteria.

Nanobubble Technology

Among the most promising water treatment technologies on the market are nanobubbles. These very small bubbles react differently than regular ones, which helps them thoroughly oxygenate water for months until they collapse.

Even in the deeper, stagnant layers of water where sediment and decaying organic matter often deplete oxygen, nanobubbles help combat pollution and maintain a healthier ecosystem. This method is also very successful at reducing odours and preventing algal blooms.

For the best solutions to polluted water, explore Love My Dam, the hub for water treatment, including dam makeover bundles and aeration equipment. Contact us today to give your dam the best chance at pristine water quality.