National Park Service

Northeast Temperate Network (NETN)

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Water is a chemical substance with the chemical formula H2O: one molecule of water has two hydrogen atoms covalently bonded to a single oxygen atom. Water appears in nature in all three common states of matter and may take many different forms on Earth: water vapor and clouds in the sky; seawater and icebergs in the polar oceans; glaciers and rivers in the mountains; and the liquid in aquifers in the ground. The major chemical and physical properties of water are: Water is a tasteless, odorless liquid at standard temperature and pressure. The color of water and ice is, intrinsically, a very light blue hue, although water appears colorless in small quantities. Ice also appears colorless, and water vapor is essentially invisible as a gas. Water is transparent, and thus aquatic plants can live within the water because sunlight can reach them. Only strong UV light is slightly absorbed.

The polar nature of water favors adhesion to other materials. Each hydrogen nucleus is bound to the central oxygen atom by a pair of electrons that are shared between them; chemists call this shared electron pair a covalent chemical bond.

Capillary action refers to the tendency of water to move up a narrow tube against the force of gravity. This property is relied upon by all vascular plants, such as trees. Water is a good solvent and is often referred to as the universal solvent. Substances that dissolve in water, e.g., salts, sugars, acids, alkalis, and some gases – especially oxygen, carbon dioxide (carbonation) are known as hydrophilic (water-loving) substances, while those that do not mix well with water (e.g., fats and oils), are known as hydrophobic (water-fearing) substances.

Importance & Issues

Water chemistry is an essential indicator to any long-term aquatic monitoring program (Gilliom et al. 1995). It is widely applicable, and critical for interpreting the biotic condition and ecological processes of all park aquatic resources. Water chemistry affects the bioavailability of contaminants, and the metabolism of aquatic species. For example, ionic conditions affect osmoregulation (Hoar and Randall 1969) and contaminant uptake (Sinley et al. 1974, Luoma 1989, Spry and Weiner 1991), dissolved oxygen and temperature affect metabolic rate (Hoar and Randall 1969). Water quality parameters are sufficiently well known that abnormal conditions and trends can be recognized or determined statistically. Information from basic water chemistry measures can be directly related to the condition of a wetland and may be correlated with other wetland vital signs. In order for causal relationships between physical and biological processes to be fully understood, it is necessary to obtain basic water chemistry measures in lakes, ponds, streams, and wetlands.

Monitoring Objectives

  • What is the natural range in variability in water-chemistry parameters for streams in each NETN park based on streams in the park that are relatively unaffected.
  • Are water-chemistry measures exceeding thresholds indicating that they are outside the range of natural variability? What is the spatial and temporal extent of these deviations?
  • Are freshwater bodies in NETN parks in compliance with the applicable Federal and state water quality standard for the highest use classifications in each state for water chemistry?
  • Are water-chemistry parameters showing long-term (> 10 year) spring, summer or fall seasonal trends after accounting for flow?
  • Can water-chemistry data be used to explain deviations in biological data at collocated sites?
  • Can changes in water chemistry be linked to trends in human activity in the park such as increased roads and (or) erosion?


Measures of water chemistry include specific conductance, pH, water temperature, and DO and are fundamental to any long-term water quality monitoring program, are critical for interpreting the biotic condition and ecological processes of a resource, and are mandatory as directed by the Inventory and Monitoring Program at the national level


Last Updated: December 30, 2016 Contact Webmaster