Without water, no life could exist, and many essential and nonessential human activities wouldn’t be possible without the use of healthy waterways. It is therefore the responsibility of us all to ensure that our local waterways, whether it be a creek, river, or lake are kept healthy and clean. Much like arteries or veins in the body, our waterways pump invaluable lifeblood through our landscapes. Monitoring the health of these vital bodies of water is therefore critical to maintaining a sustainable and healthy environment. So, what are the key measures and how do we monitor them?
Nutrient Pollution is the process where too many nutrients, mainly nitrogen and phosphorous are added to bodies of water and can act like fertiliser causing excessive growth of algae. This process is also known as eutrophication and can lead to low levels of dissolved oxygen causing the death of aquatic life. Common sources of nutrient pollution include; agricultural operations, sewerage, and industrial waste. Whilst both Nitrogen and Phosphorous are natural parts of aquatic ecosystems, an excess of these nutrients from external sources causes damage to the waterways.
Dissolved Oxygen (DO) gets into the water by diffusion from the atmosphere, aeration of water as it tumbles over falls and rapids, and as a waste product of photosynthesis. DO in a stream or waterway may vary from 0mg/L up to 18mg/L. Generally, a healthy waterway should have DO readings above 6 mg/L to support aquatic life. Reduced DO levels may be due to many factors: the water may be too warm, there may be too many bacteria, or as mentioned above, due to excessive amounts of fertilizer runoff.
Water temperature is one of the most important characteristics of an aquatic system. The main source of heat for fresh water is the sun, although temperature can also be affected by the temperature of water inputs (precipitation, surface runoff, groundwater etc.). Water temperature fluctuates between day and night (diurnal changes) and over longer periods (seasonally). Water temperature can have major impacts on: Dissolved Oxygen levels, Chemical and Biological processes, and water density.
Turbidity is caused by particles suspended or dissolved in water that scatter light, making water appear cloudy or murky. Particulate matter can include sediment – especially clay and fine silt, inorganic and organic matter, algae, and other organisms. High turbidity can significantly reduce the aesthetic quality of lakes and rivers and increase the cost of water treatment for human use. High concentrations of sediments are detrimental to aquatic ecosystems because the light that is available for plant photosynthesis is reduced. Sediment also carries with it other materials such as toxicants, pathogens, and organic matter that consume oxygen in the water column.
The pH of a water body is affected by several factors such as the soil composition through which the water moves the amount of plant growth and organic material within the water, and external sources such as the dumping of chemicals into water bodies. Even the smallest pH change can cause severe harm to aquatic life in a waterway. While there are natural sources of alkaline and acid inputs due to local geology, changes are often due to chemical spills and mine waste disposal. Acidic waters also make metal toxicants more available for plants and animals to take up and accumulate which leads to severe ecosystem impacts.
Salinity refers to how much salt is in water. The water in rivers and streams is usually fresh, oceans are salty, and estuaries are highly variable depending on tides and freshwater flows. Salinity levels may fluctuate quickly (periods of hours and days) with the tidal cycles (in response to mixing of fresh and marine waters by wind and currents), and over seasonal cycles with large freshwater flows from the catchments during wetter months. Most aquatic organisms have evolved to function within an optimal salinity range and tolerate natural cycles within this range. Long term changes to salinity distributions and their natural cycles can severely affect the health of aquatic organisms.
Whilst the factors affecting water quality are many and varied, a routine monitoring program provides insights into the overall ecosystem health and will detect any significant changes that could threaten the aquatic environment. A range of equipment and resources are available to provide easy and quick results from basic educational kits to more advanced analytical meters.