Both FDOM and Tryptophan fluorescence are measures of special optical properties of water when exposed to ultraviolet light. Think of Dissolved Organic Matter (DOM) as “staining” of water. This is different than turbidity, because DOM is dissolved in the water, whereas turbidity is caused by particles in the water. There are many types of dissolved organic matter (DOM) in most river systems, but much of this is derived from the decomposition of plant material, bacteria, and algae.

Both FDOM and Tryptophan are reported in Relative Fluorescence Units, but each measures fluorescence in slightly different wavelengths of the light spectrum. Studies have shown that use of these optical properties can improve predictions of bacterial concentrations. We are hopeful that this relatively new, commercially available, real-time, field-based technology can help better predict measurements of E. Coli in the Grand River. 

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Dissolved oxygen is the amount of oxygen present in the water. Fish, plants, and other species that call the river home need oxygen to survive. Rivers that have and abundance of aquatic plants, swiftly moving currents and turbulent riffles often have higher oxygen levels than slowly moving rivers or lakes. Oxygen is consumed in the process of decomposition of organic materials such as algal blooms.

Dissolved oxygen levels are measured in milligrams per liter (mg/L). Levels below 3 mg/L are cause for concern. Cold water can hold more dissolved oxygen than warm water, so levels are typically higher in the winter than summer.

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Specific conductance is the water's ability to carry an electric current. Conductivity in water is affected by the presence of dissolved anions (ions that carry a negative charge) such as chloride, nitrate, sulfate, and phosphate and dissolved cations (ions that carry a positive charge) such as sodium calcium, and magnesium.

Specific conductance is measured in microsiemens per centimeter (uS/cm) normalized to 25 degrees Celsius. Conductance in most rivers is largely affected by the geology (think bedrock) of the area which the water flows, but can be increased by human activities such as water softener salt use (sodium and chloride ions discharged from wastewater facilities), salting of roads in winter, and farming activities like fertilizing and manure applications. Water temperature also affects conductance, as a glass of warm water is more conductive than that same glass at a colder temperature.

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Both FDOM and Tryptophan fluorescence are measures of special optical properties of water when exposed to ultraviolet light. Think of Dissolved Organic Matter (DOM) as “staining” of water. This is different than turbidity, because DOM is dissolved in the water, whereas turbidity is caused by particles in the water. There are many types of dissolved organic matter (DOM) in most river systems, but much of this is derived from the decomposition of plant material, bacteria, and algae.

Both FDOM and Tryptophan are reported in Relative Fluorescence Units, but each measures fluorescence in slightly different wavelengths of the light spectrum. Studies have shown that use of these optical properties can improve predictions of bacterial concentrations. We are hopeful that this relatively new, commercially available, real-time, field-based technology can help better predict measurements of E. Coli in the Grand River. 

View the Data

Gage height is a term used to describe the water level, or how “high” the river is.

Gage Height is measured in feet. Some USGS stations report gage height in feet compared to mean sea level, while other stations report gage height compared to an arbitrary local datum. It is important to note that the values reported here don’t describe how deep the river actually is – they just describe how the level of the river compares to the datum.

View the Data

Both FDOM and Tryptophan fluorescence are measures of special optical properties of water when exposed to ultraviolet light. Think of Dissolved Organic Matter (DOM) as “staining” of water. This is different than turbidity, because DOM is dissolved in the water, whereas turbidity is caused by particles in the water. There are many types of dissolved organic matter (DOM) in most river systems, but much of this is derived from the decomposition of plant material, bacteria, and algae.

Both FDOM and Tryptophan are reported in Relative Fluorescence Units, but each measures fluorescence in slightly different wavelengths of the light spectrum. Studies have shown that use of these optical properties can improve predictions of bacterial concentrations. We are hopeful that this relatively new, commercially available, real-time, field-based technology can help better predict measurements of E. Coli in the Grand River. 

View the Data

Dissolved oxygen is the amount of oxygen present in the water. Fish, plants, and other species that call the river home need oxygen to survive. Rivers that have and abundance of aquatic plants, swiftly moving currents and turbulent riffles often have higher oxygen levels than slowly moving rivers or lakes. Oxygen is consumed in the process of decomposition of organic materials such as algal blooms.

Dissolved oxygen levels are measured in milligrams per liter (mg/L). Levels below 3 mg/L are cause for concern. Cold water can hold more dissolved oxygen than warm water, so levels are typically higher in the winter than summer.

View the Data

Specific conductance is the water's ability to carry an electric current. Conductivity in water is affected by the presence of dissolved anions (ions that carry a negative charge) such as chloride, nitrate, sulfate, and phosphate and dissolved cations (ions that carry a positive charge) such as sodium calcium, and magnesium.

Specific conductance is measured in microsiemens per centimeter (uS/cm) normalized to 25 degrees Celsius. Conductance in most rivers is largely affected by the geology (think bedrock) of the area which the water flows, but can be increased by human activities such as water softener salt use (sodium and chloride ions discharged from wastewater facilities), salting of roads in winter, and farming activities like fertilizing and manure applications. Water temperature also affects conductance, as a glass of warm water is more conductive than that same glass at a colder temperature.

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The temperature of the river is measured in Fahrenheit.

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Both FDOM and Tryptophan fluorescence are measures of special optical properties of water when exposed to ultraviolet light. Think of Dissolved Organic Matter (DOM) as “staining” of water. This is different than turbidity, because DOM is dissolved in the water, whereas turbidity is caused by particles in the water. There are many types of dissolved organic matter (DOM) in most river systems, but much of this is derived from the decomposition of plant material, bacteria, and algae.

Both FDOM and Tryptophan are reported in Relative Fluorescence Units, but each measures fluorescence in slightly different wavelengths of the light spectrum. Studies have shown that use of these optical properties can improve predictions of bacterial concentrations. We are hopeful that this relatively new, commercially available, real-time, field-based technology can help better predict measurements of E. Coli in the Grand River. 

View the Data

Turbidity is a measure of how clear water is. Clear water has a low turbidity, while cloudy or opaque water has higher turbidity. During baseflow conditions (low-flow) most rivers have low turbidity because the water is relatively clear. However, during rainfall-runoff events or snowmelt-runoff events, particles from the surrounding landscape are washed into rivers, often making the water a muddy brown color, resulting in higher turbidities.

Turbidity is measured in Formazin Nephelometric Units, which basically a measure of how easily an infrared light can pass through the water. Because most rivers have small bits of debris, detritus (decaying pieces of leaves, for example), particles of sediment, bits of algae and other small critters in the water, turbidity measured by a continuously-operated sonde can be fairly “noisy”. Each time one or more of these small pieces gets between the emitter of the infrared light and the sensor, there’s a small “blip” in the data. 

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Gage height is a term used to describe the water level, or how “high” the river is.

Gage Height is measured in feet. Some USGS stations report gage height in feet compared to mean sea level, while other stations report gage height compared to an arbitrary local datum. It is important to note that the values reported here don’t describe how deep the river actually is – they just describe how the level of the river compares to the datum.

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Discharge is a measure of the movement (flow) of water. Discharge is measured in cubic feet per second (ft³/s or cfs). One cfs is about the same as 7.5 gallons of water moving per second, or 450 gallons per minute.

The USGS has measured flow in the Grand River at Grand Rapids from 1902 through 1905 and from 1931 until now. Over those 95 years of measured record, the average discharge has been approximately 4,0000 cfs. The maximum observed was approximately 54,000 cfs in March of 1904.

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