Skip to content Skip to left sidebar Skip to footer

Ammonia Details

Understanding Ammonia Levels

Ammonia (NH3) is a naturally occurring compound found in soil, plants, and animal waste, and it is a key indicator of water quality in freshwater ecosystems. In freshwater streams, elevated ammonia levels can indicate a variety of environmental issues, including pollution from human activities, agricultural runoff, or natural sources (U.S. Environmental Protection Agency, 2020). Elevated levels of ammonia can also be harmful to aquatic life and can affect the overall water quality, impacting other parameters such as pH, conductivity, and nutrient levels. By monitoring ammonia levels, we can better understand the condition of our streams and their suitability for recreational activities such as swimming, fishing, and waterfall jumping.

Public and Ecosystem Health Implications of High Ammonia Levels in Streams

High ammonia levels can pose a risk to human health, especially when the water is used for recreational activities. Ammonia can irritate the skin and eyes, and in high concentrations, it can be toxic. Elevated ammonia levels may correlate with higher instances of harmful bacteria like E. coli and enterococcus, impacting public safety (Centers for Disease Control and Prevention, 2021). In 1990, the EPA issued a lifetime exposure advisory of 30 mg/L for ammonia [Minnesota Department of Health, n.d.; Oregon Department of Human Services, n.d.]. It’s important to note that advisories are non-enforceable and are intended to provide technical information to assist public health officials and water systems [U.S. EPA, n.d. a].

Ammonia and Ecosystem Health

Ammonia is essential for aquatic life, but excessive levels can disrupt the ecosystem balance. Ammonia is toxic to fish and other aquatic species, because it leads to a decrease in dissolved oxygen (DO) levels, which is vital for a healthy environment for aquatic organisms (USEPA, 2020). For aquatic life, the U.S. Environmental Protection Agency (EPA) recommends an acute threshold of approximately 2,200 micrograms/L for ammonia (NH₃) in freshwater, depending on temperature and pH (EPA, 2013). For chronic exposure, the EPA suggests a threshold of around 190 micrograms/L, also influenced by temperature and pH (EPA, 2013). The EPA has developed Aquatic Life Ambient Water Quality Criteria for ammonia in freshwater to protect aquatic organisms, not specifically for direct human recreational exposure [U.S. EPA, 2013]. These criteria are provided as guidance for states and authorized tribes to use when setting their own water quality standards [U.S. EPA, 2013]. Chronic Criterion (30-day rolling average): 1.9 mg TAN/L, not to be exceeded more than once every three years on average [U.S. EPA, 2013; Federal Register, 2013]. Additionally, the highest four-day average within a 30-day period should not exceed 4.8 mg TAN/L (2.5 times the chronic criterion) more than once in three years on average [U.S. EPA, 2013; Federal Register, 2013].

Several factors can contribute to elevated ammonia levels in Haʻikū streams

·                  Agricultural Runoff: Fertilizer and animal waste from nearby farms can introduce ammonia into streams.

·                  Septic Systems: Failing septic systems can leak ammonia into groundwater, which can eventually enter streams.

·                  Urban Stormwater Runoff: Stormwater runoff from developed areas can carry pollutants, including ammonia, into streams.

·                  Natural Sources: Decaying plant matter and animal waste can also contribute to ammonia levels.

Ammonia’s Relationship to Other Water Quality Indicators

Ammonia levels do not exist in isolation; they are interrelated with several other important water quality parameters:

·                  Dissolved Oxygen (DO): Low DO levels can result from high ammonia concentrations, as ammonia toxicity stresses aquatic life (National Oceanic and Atmospheric Administration, 2019).

·                  Conductance/Specific Conductance: These measurements indicate the presence of ions in water, including those from pollution sources that may elevate ammonia levels (American Public Health Association, 2017).

·                  pH: Ammonia toxicity varies with pH levels; higher pH can increase ammonia’s toxic effects (USEPA, 2020).

·                  Salinity: Changes in salinity can influence ammonia’s behavior and toxicity in freshwater streams (Schlumberger Water Services, 2018).

·                  Nitrites and Nitrates: These nitrogen compounds are often found alongside ammonia and can indicate nutrient pollution that affects aquatic ecosystems (USEPA, 2020).

·                  Phosphates: Similar to nitrates, phosphates contribute to nutrient pollution, potentially increasing ammonia levels (National Water Quality Assessment Program, 2018).

·                  Erosion and Sedimentation: Increased erosion can lead to higher sediment loads in streams, which can affect water quality and elevate ammonia levels (U.S. Geological Survey, 2019).