Stormwater Monitoring Parameters

stormwater-monitoring

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Stormwater monitoring shows urban runoff’s hidden impact. It involves measuring turbidity, pH, dissolved oxygen, nutrients, and pollutants like heavy metals, oils, and bacteria. This data provides information to assess ecosystem health, guide pollution prevention, and ensure that environmental regulations are being followed, safeguarding our waterways and protecting our communities. 

Stormwater monitoring is a crucial aspect of environmental management and urban planning. As cities expand and climate change shifts weather patterns, understanding the quantity and quality of stormwater runoff is important for protecting our most precious resource, water. Understanding stormwater monitoring also helps to prevent flooding and maintain the health of aquatic ecosystems. 

What Is Stormwater?

Before we dive into how stormwater is monitored, it’s critical to understand what stormwater is and why we should care about it. 

Stormwater is simply any form of precipitation (rain) that flows over land surfaces rather than being absorbed in the ground – this would be groundwater. In natural environments, most stormwater is absorbed by vegetation and soil.

However, in urban areas, these environments are usually limited and replaced with infrastructure with impervious surfaces like buildings, roads, and parking lots. Therefore, the stormwater quickly accumulates and escapes into storm drains, often picking up pollutants with it. 

Impacts Of Unmanaged Stormwater Runoff

The biggest impact of unregulated or unmanaged stormwater runoff is water pollution. As stormwater travels out of urban areas into rivers, coastal areas, and lakes, it picks up contaminants such as trash, pesticides, oil, and sediment. 

In areas with increased impervious surfaces, flooding occurs from rapid water accumulation which can overwhelm storm drains and other drainage systems. In addition, fast-moving stormwater can erode stream banks and alter natural waterways, leading to habitat destruction. Unmanaged stormwater can also pollute waterways and damage aquatic ecosystems.

But it’s not just ecosystems that are affected. When stormwater is not managed properly, frequent flooding and high volumes of water can damage urban infrastructure, so it is essential for effective management and environmental protection. 

What Key Parameters Are Measured In Stormwater?

Stormwater management/monitoring typically involves measuring the biological, chemical, and physical parameters. Each parameter provides us with valuable information about the water quality and the potential environmental impacts in an area. 

pH

The potential (power) of hydrogen, or pH, is a measurement of how acidic or basic water is. It runs on a scale ranging from 0 (highly acidic) to 14 (highly basic or alkaline), with 7 being neutral. 

Measuring pH in stormwater is important as it can greatly impact aquatic life. Most aquatic organisms have adapted to life in water and can only survive within a specific pH range. Any sudden fluctuations in pH can be fatal to fish and other aquatic animals. Also, pH can affect the solubility and availability of nutrients and heavy metals in the water.

The easiest way to measure pH is to use an electrochemical sensor. At Atlas Scientific, our pH sensors offer high accuracy and durability, making them ideal for continuous stormwater monitoring. 

Conductivity

Conductivity measures water’s ability to conduct an electrical current, and so it is directly related to the concentration of ions present in water. 

Conductivity is typically used to indicate the presence of inorganic dissolved solids like chloride, sulfate, nitrate, sodium, phosphate, magnesium, iron, calcium, and aluminum. When the conductivity level is high it may suggest that the water is polluted from sewage, industrial discharges, or road salt.

Conductivity is measured using a conductivity meter and probe. A conductivity meter provides accurate readings across a wide range of conductivity levels, which is vital for diverse stormwater environments. 

Dissolved Oxygen 

Dissolved oxygen (DO) refers to the level of free, non-compound oxygen present in a body of water. Oxygen enters the water by direct atmospheric absorption, a byproduct of aquatic plant photosynthesis, and groundwater discharge. Sufficient dissolved oxygen levels are essential for aquatic organisms to survive. When water has a low DO level it can kill fish and degrade aquatic ecosystems. The depletion of DO levels is usually from the presence of organic matter, often from pollutants found in stormwater runoff.

Dissolved oxygen is best measured using optical or electrochemical sensors. Atlas Scientific’s DO sensors use advanced technology to provide accurate readings even in challenging conditions. 

Turbidity

Turbidity measures the clarity of water and indicates the amount of particulate matter suspended in the water. When turbidity is high in water it can seriously harm aquatic life due to the reduction of light penetration which affects plant growth. High turbidity can also clog fish gills and transport pollutants. 

An optical turbidity sensor provides reliable measurements across a wide range of turbidity levels to maintain turbidity in stormwater. 

Temperature

Water temperature is a critical factor in aquatic environments because it affects the rate of chemical reactions, the metabolic rates of aquatic organisms, and the solubility of gasses such as oxygen. 

Sudden changes or drastic fluctuations are usually caused by urban stormwater runoff. Temperature is measured using a thermostat, which is usually integrated into a temperature sensor or multi-parameter probe for those looking for more comprehensive monitoring. 

Nutrients 

Nutrients such as nitrogen and phosphorus are important for plant growth but in excess, they can quickly become pollutants. Excessive nutrients found in stormwater runoff can cause eutrophication which often leads to harmful algal blooms, dissolved oxygen depletion, and potential fish kills. Sources of increased nutrients include animal waste, fertilizers, and atmospheric deposition.

Implementing sustainable stormwater monitoring can prevent water pollution.  Nutrients are usually measured via laboratory analysis. But, when continuous monitoring is required, ion-selective electrodes can be used to measure parameters like nitrate. 

Heavy Metals

Heavy metals such as zinc, lead, copper, and cadmium can be present in urban stormwater runoff, which can be toxic to aquatic life and bioaccumulate in the aquatic food chain. 

Heavy metals often come from roofing and other infrastructure materials, industrial activities, and vehicle brake pads.

To accurately measure heavy metals in stormwater, laboratory analysis is typically required. However, in some cases, volumetric sensors can provide in-situ measurements for certain metals. 

Total Suspended Solids (TSS)

Total suspended solids (TSS) measure the amount of suspended material in water. High levels of TSS can negatively impact aquatic organisms by reducing light penetration and smothering benthic habitats. TSS can also carry other water pollutants attached to dissolved particles. 

While TSS is often measured in a laboratory, turbidity measurements can usually be an indication of TSS in stormwater monitoring. 

Oil & Grease

Oil and grease in stormwater most often come from oil spills, vehicle leaks, and improper disposal. Even if a tiny amount of oil enters the water, it can be toxic to aquatic life. Oil can also create a sheen on water surfaces which impacts oxygen transfer.

Some optical sensors can detect the presence of hydrocarbon sheens on the water’s surface, but usually, oil and grease have to be sent off for laboratory analysis. 

Bacteria

Fecal coliform bacteria like E.coli are prime indicators of potential pathogen contamination in water. Bacteria pollution such as this suggests contamination from animal waste or sewage, posing risks to human health if the water is used for municipal water supplies like drinking water. 

Bacterial levels are sent to laboratories but newer rapid testing methods and sensors for certain indicators are being developed for easier monitoring. 

Flow Rate & Volume

Now you may be thinking that these are not a water quality parameter per se, however, measuring the quantity of stormwater is crucial for understanding pollutant loads and system performance.

Collecting flow data is important for calculating total pollutant loads, assessing the performance of Best Management Practices (BMPs), and designing stormwater infrastructure.

Flow can be measured using a variety of methods, but we recommend a flow meter to provide accurate measurements even in challenging conditions. 

Continuous Stormwater Monitoring Systems

While grab sampling and laboratory analysis play a key role in stormwater monitoring, there is an increasing trend towards continuous, real-time monitoring systems. 

The Advantages Of Continuous Monitoring 

  • Real-time data for rapid response to pollution events like oil spills.
  • The ability to capture the ‘first flush’ of stormwater, which often carries the highest pollutant loads.
  • Comprehensive data sets that allow for trend analysis 
  • Reduced labor costs compared to frequent and manual sampling and monitoring.

At Atlas Scientific, our sensors are well-suited for integration into continuous monitoring systems, offering high accuracy and durability.

Challenges In Stormwater Monitoring

Despite the advances in sensor technology, stormwater monitoring can still present some challenges:

  • Variability – Stormwater quality and quantity can vary between events and even within a single storm, which can make representative sampling challenging.
  • Harsh conditions – Monitoring equipment needs to withstand exposure to sediment, debris, and potentially corrosive pollutants.
  • Maintenance – Sensors require regular cleaning and calibration to ensure accuracy, particularly in stormwater containing debris. However, we offer affordable calibration solutions for all of our water quality sensors so you can do it yourself. 
  • Data management – Continuous monitoring systems generate large volumes of data, which typically requires robust data management and analysis tools. 
  • Cost – Extensive monitoring programs can be expensive.

Tips For Successful Stormwater Monitoring

To ensure the success of a stormwater monitoring program:

  • Invest in high-quality sensors to ensure reliable data
  • Regularly calibrate your monitoring equipment to maintain accuracy – we offer calibration solutions for all our sensors
  • Understand what you want to achieve with your monitoring program
  • Select testing parameters that align with your objectives and local environmental concerns
  • Choose monitoring locations that are safe to access and are representative of the area
  • Regularly review stormwater monitoring data to improve stormwater practices and make informed management decisions

Summary

Effective stormwater monitoring is vital for protecting our water resources, maintaining healthy ecosystems, and preventing flooding. By measuring a wide range of parameters – from pH and conductivity to nutrients and oil spills, we can gain a better understanding of stormwater quality and its potential impacts.

At Atlas Scientific, we have revolutionized our ability to monitor stormwater continuously and in real-time. As our cities continue to grow and climate change alters rain patterns, the importance of measuring stormwater will only increase. 
If you would like to know more about the wide range of sensors we offer for stormwater monitoring, do not hesitate to contact the world-class team at Atlas Scientific. Together we can better manage our stormwater, protect our environments, and build more resilient communities for the future.

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