Rising nitrate levels in municipal water in the winter is a very common occurrence. Read this:
Nitrates On the Rise in Winter
You might start noticing something with your nitrate test results as we enter the winter season - they might increase. Nitrates (converted from nitrogen) is a nutrient needed by living organisms for protein development and DNA / RNA synthesis, and it is naturally present in our aquatic systems. The levels of nitrates can fluctuate seasonally from both natural and human influences. An increase in this level usually begins in November.
Why is this happening? What are some of the natural causes for this increase that happens in all streams? Think about what is happening out there in the environment during this time of year that would add nutrients to soil and streams. What might be some of the human influences for the change?
Nitrates (a form of nitrogen in water) are needed by all living plants and animals to help build proteins, DNA, and RNA. From soil, plants retrieve nitrates with their roots; animals obtain nitrates by eating plants directly or indirectly. Eventually, all the accumulated nitrates in an organism are returned to the soil through excretion (waste production) or by dying and decomposing. This is a simplified version of the nitrogen cycle.
The winter rise...There are a number of reasons why nitrate levels increase during the winter. Decaying leaves and dead terrestrial (land) and aquatic plants were adding nitrates. Because vegetation is dormant (not growing) during this season means that the roots are not taking up nutrients. Instead they can be washed into the stream by rain and snow melts, especially off of bare agricultural fields.
Increased use of agricultural and lawn fertilizers can also be an input all year round. Sewage can be added to a stream any day. This includes malfunctioning septic systems outside of homes and failing municipal sewage plants. Any outdated plants that treat both sewage and storm runoff cannot handle high volumes of water after snow melts and storms. So it is sometimes sent into the waterway only partially treated. In addition to human sewage, animal waste from pastures is another nitrates input. Ever see a cow standing in a stream? Plop, plop.
But aren't nutrients needed in a stream? Yes, but too much can disrupt the normal aquatic environment. More nutrients in the water would encourage excessive algal and plant growth. Green soupy water could appear. Even though plants produce oxygen, needed by the creatures living in the water, there is still a problem. Eventually the algae dies. When plants die, the process of decomposition (bacteria at work here) sucks up the oxygen - taking it away from the fish, insects, and mussels living in the water.
Nitrates in drinking water may also be a health risk to humans, especially babies. Therefore, the EPA sets a limit of 10 ppm of nitrate for public drinking water. So keep an eye on your nitrate levels and see if there is any increase during the winter.
