Measuring and Mapping Water Health and Pollution in the Patapsco and its Tributaries

 Phycoerythrin

What is Phycoerythrin?

Phycoerythrin is a type of blue-green pigment found in some phytoplankton, such as Cyanobacteria and Cryptophyceae. Phycoerythrin is measured as a concentration in cells per milliliter (cells/mL). Because Phycoerythrin is contained within blue-green phytoplankton, it can be used as an indicator for the amount of Cyanobacteria present in the water.

Why is Phycoerythrin important?

As an indicator for the amount of blue-green phytoplankton in waterways, Phycoerythrin is important for determining whether Cyanobacteria are present at ecologically healthy levels. When too much nutrients pollution, measured by Total Nitrogen and Total Phosphorus, is present in the water, Cyanobacteria will rapidly reproduce, resulting in blooms comprised of potentially-harmful species that secrete toxins that under some circumstances may stress or kill fish and other aquatic animals. Less often, these toxins may also pose a risk to humans.

How do we measure Phycoerythrin?

Phycoerythrin is measured with an optical probe that is lowered from our WATERKEEPER boat into the water at each station location. Phycoerythrin readings are automatically collected at 0.5 or 0.25 meter intervals from the water’s surface to just above the river bottom. We assess the Phycoerythrin data for readings collected above the pycnocline [wiki hyperlink here] using the World Health Organization’s numeric human health threshold of 20,000 cells/mL.

Chlorophyll α

What is Chlorophyll α?

Chlorophyll α is a type of green pigment, essential for photosynthesis, found in most algae and phytoplankton. Chlorophyll α is measured as a concentration in micrograms per liter (µg/L). Because Chlorophyll α is contained within algae, it can be used as an indicator for the amount of green-pigmented algae present in the water.

Why is Chlorophyll α important?

As an indicator for the amount of algae in waterways, Chlorophyll α is important for determining whether algae are present at ecologically healthy levels. When there is too much nutrient pollution (measured by Total Nitrogen and Total Phosphorus) present in the water, algae will rapidly reproduce and create visible blooms of algae in the water. Sometimes these algae blooms are comprised of harmful species that secrete toxins that can stress or kill fish and other aquatic animals. Oftentimes, when algae blooms die they are decomposed by bacteria that consume oxygen and cause a rapid decline in dissolved oxygen levels. These conditions can also stress or kill fish and other aquatic organisms. However, lower levels of Chlorophyll α are important to indicate that enough algae are present to serve as food for other aquatic creatures.

How do we measure Chlorophyll α?

We measure Chlorophyll α using two different methods. First, using an optical probe lowered from our WATERKEEPER boat into the water at each station location, we collect readings at 0.5 or 0.25 meter intervals from the water surface to just above the river bottom. Second, we collect a water sample from 1 meter below the water’s surface at each station, store samples on ice, and deliver samples the same day to a laboratory for analysis. We assess Chlorophyll α data using a numeric ecological threshold of <15 µg/L, which was established through scientific studies carried out by Maryland Department of Natural Resources biologists and academic researchers.

Fecal Bacteria

What is Fecal Bacteria?

Fecal bacteria are bacteria from animal (including human) waste or feces, and are measured as a concentration of bacterial colonies (colonies/100mL) present in the water. Fecal bacteria are a diverse group of microorganisms, and there are several different groups of fecal bacteria that are used for monitoring water. For this study, we measure the concentration of Enterococcus fecal bacteria, which are used as an indicator for potential sewage contamination and human health risk from water contact. Fecal bacteria enter waterways through stormwater runoff that carries fecal bacteria from animal waste deposited throughout the environment, such as pet waste, and through overflows of human sewage from septic tanks, sanitary sewer pipes, and wastewater treatment plants.

More information

Why is Fecal Bacteria important?

Enteroccocus fecal bacteria are a reliable indicator for waterborne pathogens that are excreted by mammals and humans, such as Staphylococcus, Hepatitis A, Cryptosporidium, West Nile Virus, and other microorganisms that can cause gastrointestinal illness and skin and eye infections. For this reason, collection of this data is important for assessing the human health risk of recreational water contact.

How do we measure Fecal Bacteria?

Fecal bacteria are measured through the collection of a water sample for analysis by a laboratory. We collect a water sample from halfway between the water’s surface and river bottom at each station, store samples on ice, and deliver samples the same day to the laboratory for analysis. We assess the Enterococcus fecal bacteria data using the State of Maryland’s numeric human health thresholds for body-contact water recreation (“Low Risk” < 61 colonies/100mL; “Medium Risk” 61 - 151 colonies/100mL; “High Risk” > 151 colonies/100mL). 

Temperature

What is Temperature?

Temperature is the measurement of the heat energy of the water, and, for many scientific applications, Temperature is measured in degrees Celsius. Temperature is affected by many factors, including ambient air temperature, flow and volume of water in the waterway, stormwater runoff, as well as other natural and human sources of physical and chemical thermal pollution.

Why is Temperature important?

Aquatic plants and animals are evolutionarily adapted to live in different ranges of Temperature with gradual changes due to changing seasons. When the Temperature of the water changes rapidly and exceeds the acceptable range for various aquatic organisms, those organisms may die, become stressed, or become excluded from their habitat. Other critical water-quality parameters, such as Dissolved Oxygen, are dependent on Temperature.

How do we measure Temperature?

Temperature is measured with a probe that is lowered by staff or volunteers into the water at each station location. Temperature readings are recorded half-way between the water’s surface and the river bottom. We assess the Temperature data using the State of Maryland’s instantaneous numeric thresholds of 32°C (Use Class I streams and rivers), 23.9°C (Use Class IV), and 20°C (Use Class III), which ensures the protection of the ecological health of fish populations in the State’s streams and rivers.


Total Nitrogen

What is Total Nitrogen?

Total Nitrogen is a measurement of how much elemental nitrogen in various molecular formations is present in the water. Total Nitrogen is measured as a concentration in milligrams per liter (mg/L). Nitrogen enters nontidal freshwater streams and rivers from organisms that naturally live in and around the water and through discharges of various sources of water pollution, such as sewage overflows, industrial discharges, and stormwater runoff containing animal waste and fertilizers, among other nitrogen-rich substances in the watershed.

Why is Total Nitrogen important?

Nitrogen is an essential element for cellular formation of plant, bacteria and animal life. As a limiting nutrient, excess levels of nitrogen and phosphorus in nontidal freshwater streams and rivers can drive rapid population “blooms” of bacteria and algae populations, which can have serious impacts on other aquatic and human life. These algae and bacteria blooms may secrete toxins harmful to fish and humans, and, when algae blooms die and are decomposed by bacteria, levels of dissolved oxygen can rapidly decline. These excess levels of nitrogen and phosphorus are often discharged to receiving tidal waters from watershed rivers and streams before they can contribute to algae blooms occurring within the rivers and streams.

How do we measure Total Nitrogen?

Total Nitrogen is measured through the collection of a water sample for analysis by a laboratory. We collect a water sample from halfway between the water’s surface and river bottom at each station, store samples on ice, and deliver samples the same day to the laboratory for analysis. We assess the Total Nitrogen data using numeric thresholds of ≤0.64 mg/L (Piedmont Streams and Rivers) and ≤0.82 mg/L (Coastal Plain Streams and Rivers), as established by the University of Maryland Center for Environmental Science’s EcoCheck Program for the assessment of the ecological health of nontidal freshwater streams and rivers in the Chesapeake Bay watershed.


 

Total Phosphorus

What is Total Phosphorus?

Total Phosphorus is a measurement of how much elemental phosphorus in various molecular formations is present in the water. Total Phosphorus is measured as a concentration in milligrams per liter (mg/L). Phosphorus enters nontidal freshwater streams and rivers through discharges of various sources of water pollution, such as sewage overflows, industrial discharges, and stormwater runoff containing animal waste and fertilizers, among other phosphorus-rich substances in the watershed.

Why is Total Phosphorus important?

Phosphorus is an essential element for cellular formation of plant, bacteria and animal life. As a limiting nutrient, excess levels of nitrogen and phosphorus in nontidal freshwater streams and rivers can drive rapid population “blooms” of bacteria and algae populations, which can have serious impacts on other aquatic and human life. These algae or bacteria blooms may secrete toxins harmful to fish and humans, and, when algae blooms die and are decomposed by bacteria, levels of dissolved oxygen can rapidly decline. These excess levels of nitrogen and phosphorus are often discharged to receiving tidal waters from watershed rivers and streams before they can contribute to algae blooms occurring within the rivers and streams.

How do we measure Total Phosphorus?

Total Phosphorus is measured through the collection of a water sample for analysis by a laboratory. We collect a water sample from halfway between the water’s surface and river bottom at each station, store samples on ice, and deliver samples the same day to the laboratory for analysis. We assess the Total Phosphorus data using numeric thresholds of ≤0.01 mg/L (Piedmont Streams and Rivers) and ≤0.02 mg/L (Coastal Plain Streams and Rivers), as established by the University of Maryland Center for Environmental Science’s EcoCheck Program for the assessment of the ecological health of nontidal freshwater streams and rivers in the Chesapeake Bay watershed. 

 Turbidity

What is Turbidity?

Turbidity is the measurement of how much light can penetrate through the water. Turbidity is measured in Nephelometric Turbidity Units (NTU), and is an indicator of how much particles, such as sediment and phytoplankton, are suspended in the water.

Why is Turbidity important?

Low Turbidity levels are important for the survival of aquatic plants and animals. Low levels of Turbidity allow sunlight to reach aquatic plants, permitting critical fish-habitat forming plants to photosynthesize. Low levels of Turbidity also indicate low levels of suspended solid particles, like algae, sediment, and other pollutants, that may otherwise interfere with the ability of aquatic animals to respire (breathe) and locate crucial food and habitat. High levels of Turbidity often indicate high levels of sediment pollution, which can settle on stream and river bottoms, smothering stream macroinvertebrate insects and fish spawning habitat.

How do we measure Turbidity?

Turbidity is measured using a portable field instrument and water samples. Samples are collected half-way between the water’s surface and the river bottom and analyzed with the field instrument. We assess the Turbidity data using the State of Maryland’s instantaneous numeric threshold of 150 NTU for protecting the ecological health of fish populations in the State’s freshwater streams and rivers from harmful levels of Turbidity.


 Water Clarity

What is Water Clarity?

Water Clarity is the measurement of how much sunlight can penetrate through the water. Water Clarity is measured as a distance in decimeter units (dm) from the water’s surface to the depth where sunlight can no longer penetrate the water. Water Clarity is diminished when solid particles, such as dirt and algae, are suspended in the water column and absorb or reflect sunlight.

Why is Water Clarity important?

High water clarity is important for the survival of aquatic plants and animals. High water clarity allows sunlight to reach aquatic plants, permitting critical fish habitat-forming plants like bay grasses to photosynthesize. High water clarity also indicates low levels of suspended solid particles, like sediment (silt and clay particles from soil) and algae, that may otherwise interfere with the ability of aquatic animals to respire (breathe) and locate food and habitat.

How do we measure Water Clarity?

Water Clarity is measured using an instrument called a Secchi Disk. The black- and white-colored weighted disk is attached to a graduated line and is lowered into the water up until the point that the disk is no longer visible. At the depth the disk disappears a reading is recorded on the line, and the Secchi disk is slowly retrieved until it reappears, at which point another reading is recorded. The average value of the two readings provides the Secchi depth data value. We assess Water Clarity data using the State of Maryland’s instantaneous numeric threshold of ≥10 dm for the protection of the ecological health of aquatic plant and animal populations in the Chesapeake Bay.

 pH

What is pH?

pH is the measurement of the concentration of hydrogen ions in the water. pH is measured on a logarithmic scale (0-14 pH units), with values on the lower end of the scale considered acidic (high levels of H+ ions) and higher values considered basic (lower levels of H+ ions). The carbonate system is a natural process that maintains pH equilibrium in waters impacted by the photosynthesis and respiration of aquatic plants and decomposition by bacteria. Pollution from sewage overflows, stormwater runoff, carbon dioxide emissions, chemical spills and acid precipitation can negatively impact healthy pH levels.

Why is pH important?

Consistent and moderate levels of pH are critical for the survival of aquatic life, because pH affects the availability of essential nutrients and minerals, as well as the presence of toxic substances in the water. Acidic waters (low pH) impede the ability of freshwater invertebrates to build their calcium carbonate shells. Low pH levels also increase the availability of phosphorus, driving algae blooms that can ultimately result in harmful decreases of dissolved oxygen. Basic waters (high pH) also increase the availability of ammonia, which is toxic to aquatic life.

How do we measure pH?

pH is measured with a probe that is lowered by staff or volunteers into the water at each station location. pH readings are recorded half-way between the water’s surface and the river bottom. We assess the pH data using the State of Maryland’s instantaneous numeric threshold range of 6.5 – 8.5 (SU pH), which ensures the protection of the ecological health of animal and plant populations in the State’s streams and rivers from harmful acidic or basic pH conditions.

Salinity

What is Salinity?

Salinity is the measurement of the concentration of dissolved salt content of the water. Salt compounds, which originate through erosion of rocks, include chemicals such as sodium chloride, magnesium sulfate, and sodium bicarbonate and, when dissolved, are present as ions in the water. Salinity is affected by the relative input of freshwater, from watershed streams and rivers, and input of saltwater through the Bay from the Atlantic Ocean. Salinity is measured in Parts Per Thousand (PPT) and can range from nearly 0 in freshwater to 35 in the open ocean.

Why is Salinity important?

Aquatic plants and animals are evolutionarily adapted to live in different levels of salinity. When salinity levels change and exceed the acceptable range for various aquatic organisms, those organisms, such as aquatic plants like bay grasses, may be excluded from their habitat

How do we measure Salinity?

Salinity is measured with a probe that is lowered from our WATERKEEPER boat into the water at each station location. Salinity readings are automatically collected at 0.5 or 0.25 meter intervals from the water’s surface to just above the river bottom. The State of Maryland has not established an assessment threshold for Salinity, but we utilize our Salinity data to measure the pycnocline in the water column in order to assess Dissolved Oxygen data. 

Dissolved Oxygen

What is Dissolved Oxygen?

Dissolved Oxygen is the measurement of how much oxygen is present in the water and available to aquatic organisms. Dissolved Oxygen is measured as a concentration in milligrams per liter (mg/L) and as a percent-saturation, which indicates how much oxygen the water is capable of holding at any given temperature. Dissolved Oxygen enters non tidal freshwater streams and rivers through physical mixing at shallow stream riffles and man-made structures and as a by-product of photosynthesis by algae and aquatic plants.

Why is Dissolved Oxygen important?

Dissolved Oxygen is an essential element for the survival of most aquatic animal life, such as the fin-fish and stream macroinvertebrate insects that breathe underwater. These aquatic animals may avoid areas of water with very low levels of Dissolved Oxygen. Sometimes, the aquatic animals will become trapped in areas with low-levels of Dissolved Oxygen, which means that they may suffocate and die. Oftentimes, very low levels of Dissolved Oxygen result when algae blooms are decomposed by bacteria, which rapidly consume Dissolved Oxygen in the water, or when chemical pollutants, such as sulfur, react to rapidly deplete levels of Dissolved Oxygen.

How do we measure Dissolved Oxygen?

Dissolved Oxygen is measured with a probe that is lowered by staff or volunteers into the water at each station location. Dissolved Oxygen readings are recorded half-way between the water’s surface and the river bottom. We assess the Dissolved Oxygen data using the State of Maryland’s instantaneous numeric threshold of 5.0 mg/L for protecting the ecological health of fish populations in the State’s freshwater streams and rivers.

Conductivity

What is Conductivity?

Conductivity is the measurement of how well the water conducts electricity through its content of ions and is measured in standard unit microSiemens per centimeter (µS/cm). Naturally occurring ions include calcium and magnesium, but urban streams and rivers are also subject to pollution from sewage overflows, industrial discharges, and stormwater runoff containing nitrate, phosphate, chloride, salt, and metals ions.

Why is Conductivity important?

Conductivity can be an indicator of an unnatural or harmful imbalance of the ion content of the water. Low levels of Conductivity may indicate a lack of elements essential for aquatic life, such as calcium and magnesium, due to pollution discharges containing noncharged ions, such as oil and phenols. High levels of Conductivity may indicate harmful levels of toxic chloride, salt and metals ions from pollution discharges from sewage, stormwater, and industrial sources.

How do we measure Conductivity?

Conductivity is measured with a probe that is lowered by staff or volunteers into the water at each station location. Conductivity readings are recorded half-way between the water’s surface and the river bottom. The State of Maryland has not established an assessment threshold for Conductivity.