Water Quality Monitoring at Arlington Echo

During the fourth grade Arlington Echo outdoor education experience, students engage in lessons and activities at our campus on the Indian Creek, which is a small tributary of the Severn River. These activities include seining to look for fish and other organisms in Indian Creek, using plankton tows and microscopes to identify microorganisms living in the water, and taking water quality measurements to determine the health of Indian Creek.

In the fall of 2016 we began recording our water quality measurements to monitor the health of the Indian Creek and track changes over time. The map below shows our monitoring site location, and the graphs display our current data, collected in Spring 2018. Older data can be found in our archived data section.

Water quality measurements taken include:

• Temperature – how warm or cold the water is; measured in degrees Fahrenheit using a floating thermometer. Though the water temperature naturally fluctuates throughout the season, animals depend on relatively consistent water temperatures during certain times of the year. In Indian Creek, the average water temperature ranges from about 38 degrees Fahrenheit in mid-January up to about 85 degrees in mid-July. Temperature shares a direct relationship with dissolved oxygen levels in the water, because colder water holds more oxygen than does warmer water. Additionally, stormwater runoff from paved surfaces like sidewalks and roads enters the waterways at a higher temperature than runoff that soaks in through pervious surfaces, increasing the overall water temperature.

• Salinity – the amount of salt dissolved in the water; measured in parts per thousand (ppt) using a handheld salinity meter. Different plants and organisms require certain salinity levels for survival and reproduction, and generally cannot survive through drastic fluctuations in salinity. Salinity can be affected by runoff, particularly in the winter when roads are salted and that salt gets washed into nearby rivers and streams. Rainfall also affects salinity; precipitation events add more fresh water to waterways, leading to a lower salinity, while the dry season can lead to more evaporation and thus a higher salinity. Ocean water has a salinity of about 35 ppt, while the Chesapeake Bay averages a salinity around 15 ppt. Inland freshwater rivers and streams have a salinity close to 0 ppt. The Indian Creek is brackish, meaning that it is a mixture of fresh and saltwater, and generally has a salinity range of about 3 – 10 ppt, depending on the season.

• Turbidity – the amount of suspended sediment in the water; measured in centimeters of water depth using a turbidity tube. Ideal conditions for animals and plants in the water occur when turbidity is low and clarity is high. Low turbidity allows animals to more easily see through the water and use their gills to absorb oxygen, and allows for plants to receive sunlight, which they need to survive and provide oxygen and habitat for other living things. Turbidity increases after heavy rainstorms when runoff washes eroded soil into waterways. High turbidity can also result from excess bacteria or algae in the water.

• Dissolved Oxygen – the amount of available oxygen dissolved in the water; measured in parts per million (ppm) using dissolved oxygen tablets. Oxygen is vital for life to survive in the water. Most species that live in Indian Creek are able to survive and reproduce successfully when dissolved oxygen levels are at or above 5ppm, though some species are more tolerant to low oxygen levels than others. Dissolved oxygen levels can be affected by water temperature, because colder water holds more oxygen than warmer water, and by the presence of plant life in the water, because plants emit oxygen as a byproduct of photosynthesis. In addition, algal blooms caused by runoff of excess nutrients from fertilizer, animal waste, or septic systems can result in a loss of oxygen, known as a “dead zone,” as algae blocks underwater plants from getting sunlight for photosynthesis and as bacteria use up all available oxygen in the water when decomposing the algae.

Monitoring Site Location:

Archived Water Quality Data:

• Fall 2016

All data and content on this website are property of Anne Arundel County Public Schools. Please credit Anne Arundel County Public Schools and Arlington Echo Outdoor Education Center when citing or using data and content for any purpose.

All data are offered for educational purposes only. Data presented are provisional, subject to later correction, and have not undergone full quality control procedures. Missing data may result from equipment malfunctions or the rejection of ‘bad’ data during review.

Data are gathered by students with the help of adult volunteers, teachers, and Arlington Echo staff. In some circumstances, including extreme weather, students do not go out to test water quality. This may result in some inconsistencies in the reporting and/or content of the data.