This website presents the results of long-term monitoring of streams in eleven national parks. The goal of the monitoring is to determine the status and trends of water quality, as demonstrated by a variety of water quality measures. The streams chosen are those which flow year round, are not tidal and are wadable (1st - 4th order). Monitoring of each stream takes place at a fixed location near to where the stream exits the park or flows into a larger stream. For detailed methods, please consult the data collection protocol listed in the Citations & References tab above.
This results displayed on this website are based on data which has undergone a QA/QC process and has been accepted. Data which is below the detection or quantification limit is only displayed in the Graphs Panel on this website.
This website provides information on the following measures of water quality.
Acid Neutralizing Capacity (ANC): ANC is the prime indicator of a waterbody's susceptibility to acid inputs. The higher the ANC of a waterbody, the better able it is to resist the effects of acid. It is a measure of the amount of compounds in the water that neutralize low pH. The measured ANC refers to the alkalinity of an unfiltered water sample (i.e. alkalinity due to both dissolved and suspended matter). This is different than the pH of the stream, as pH measures acidity, but does not measure "buffering capacity". ANC is typically caused by anions (negatively charged particles) in natural waters that can enter into a chemical reaction with a strong acid. These are primarily the carbonate (CO32-) and bicarbonate (HCO3-) ions. Borates, phosphates, silicates, arsenate, ammonium, and organic ligands (e.g. acetate and propionate) can also contribute to alkalinity when present.
Dissolved Oxygen (DO) in mg/L or % saturation: DO is a measure of the amount of oxygen in water. DO is necessary in aquatic systems for the survival and growth of many aquatic organisms. Dissolved oxygen can enter water by photosynthesis of plants or directly from the atmosphere, and it is lost by temperature rise, plant and animal respiration, and bio-chemical reactions. The DO concentration of surface water also depends on water temperature and air pressure. High pressures and cool temperatures allow more oxygen to be dissolved in the water. Due to changes in temperature, DO has strong daily and seasonal variability.
Low DO is of greatest concern because of its detrimental effects on aquatic life. Conditions that generally contribute to low DO levels include warm temperatures, low flows, water stagnation and shallow gradients in streams, organic matter inputs, and high respiration rates. Decay of excessive organic debris from aquatic plants, municipal or industrial discharges, or storm runoff can also cause low DO. Insufficient DO can lead to unsuitable conditions for aquatic life.
We include two measures of DO: milligrams per liter (mg/L) and % saturation. Milligrams per liter indicates the absolute amount of oxygen present in the water, whereas % saturation indicates how much is present as compared to a theoretical maximum determined by water temperature.
pH: The pH of water is a measure of how acidic or basic a stream is. The term pH stands for "power of hydrogen." More hydrogen ions results in a lower pH. pH is measured on a scale that most commonly ranges from 0 (acid) to 14 (basic/alkaline). Pure water has a pH of 7 (neutral). The pH scale is "logarithmic" meaning each pH unit increase represents a 10X decrease in hydrogen ion concentration.
The pH of water is important to aquatic life, as it has a profound impact on the toxicity and solubility of many chemicals. The toxicity of ammonia, aluminum, and some other contaminants is partially determined by pH. Changes in pH affect the dissociation of weak acids or bases, which in turn affects the toxicity of many compounds. For example, hydrogen cyanide toxicity to fish increases with lowered pH, whereas rapid increases in pH increase NH3 (ammonia) concentrations. Metal mobility is also enhanced by low pH which can have a significant impact on water bodies located in areas contaminated by heavy metals (e.g. mining).
Salinity: Salinity is a measure of the amount of salt dissolved in the water. While freshwater streams naturally have some salt content, this can be increased by pollutants. One notable cause of increased salinity in streams is road salt and other deicing compounds that are washed off of road in the winter. Salinity is measured in parts per thousand or "ppt". Freshwater has 0 - 0.5ppt, brackish water is 0.5 to 30 ppt and saltwater is above 30ppt.
Specific Conductance: Specific conductance is a temperature corrected measure of the electrical conductivity of water and is directly related to concentration of ions. Conductivity is a measure of the capacity of water to conduct an electrical current. The conductivity of water is highly dependent on temperature and may change as much as 3% for each 1 degree C change. Thus a large apparent change in conductivity may simply be due to water temperature, and not due to changes in ions in the water. Specific conductance is a measure of conductivity of water which takes water temperature into account. Specific conductance is dependent upon the types and quantities of dissolved substances and is a good indication of total dissolved solids and total ion concentration.
The electrical conductivity of a water body has little or no direct effect on aquatic life. However, an increase in conductivity may indicate an increase of an ion that is toxic to aquatic life. Specific conductance is also useful in estimating the concentration of dissolved solids in water. Electric current is carried by dissolved inorganic solids such as chloride, carbonate, nitrate, sulfate, and phosphate anions (negatively charged particles), as well as sodium, calcium, magnesium, potassium, iron, and aluminum cations (positively charged particles). Common sources of pollution that can affect specific conductance are deicing salts, dust reducing compounds, agriculture (primarily from the liming of fields), and acid mine drainage (U.S. Geological Survey 1980, Stednick and Gilbert 1998, National Park Service 2002). In an analysis of data from the Maryland Biological Stream Survey, Morgan et al. (2007) found a critical value for conductivity of less than 247 uS/cm for macroinvertebrates and less than 171 uS/cm for fish.
Total Nitrate: Nitrate is one of the dissolved, inorganic forms of nitrogen most available for biological uptake and the chemical transformation that can lead to eutrophication of water bodies. Nitrate is highly mobile in surface and groundwater and may seep into streams, lakes, and estuaries from groundwater enriched by animal or human wastes and commercial fertilizers. High concentrations of nitrate can enhance the growth of algae and aquatic plants in a manner similar to enrichment in phosphorous and thus cause eutrophication of a water body. In most natural waters, inorganic nitrogen as ammonium or nitrate is not the growth-limiting nutrient unless phosphorous is unusually high.
Total Phosphorus: Phosphorus (measured as PO4) is frequently a limiting nutrient in aquatic systems. A minor increase in phosphorous concentration can significantly affect water quality by changing the population and community dynamics of algae and diatoms leading to eutrophication (Allan 1995). Phosphorus is singled out as an especially important actor in the Heinz Center Report (2002) on the state of nation's ecosystems. Sources of phosphorous include sediments, fertilizer application (e.g. irrigation return flow), soaps, and detergents.
Water Temperature: Several of the water chemistry parameters are water temperature dependent, such as: DO and specific conductance. High temperature can also stress aquatic life particularly those adapted to habitats with cooler temperatures such as trout.
This website provides information on the following measures of water quantity.
Discharge: Discharge of a stream is a measure of the volume of water in a stream. It is measured by calculating how much water passes a given cross-section of the stream per second and is measured in cubic feet of water per second.
Additional data is collected druing stream monitoring to provide context to the stream data.
Atmospheric Pressure: An atmospheric pressure reading is taken during each monitoring event. This reading is used to when calculating % saturation of dissolved oxygen.
Air Temperature: Air temperature readings are taken duirng each monitoring event.
For a complete description of the project and its methods, see Norris et al, 2013 in the Citaitons & References tab.