Nutrients
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While both phosphorus and nitrogen are essential nutrients for plants and animals that make up the aquatic food web (nitrogen for protein synthesis and phosphorus for energy transformation in cells), in excess amounts they can cause severe problems.

Since phosphorus is the nutrient in short supply in most fresh waters, even a modest increase in phosphorus can, under the right conditions, set off a whole chain of undesirable events in a stream including accelerated plant growth, algae blooms, low dissolved oxygen, and the death of certain fish, invertebrates, and other aquatic animals. This over-fertilization is called eutrophication. There are many sources of phosphorus in water, both natural and human. These include soil and rocks, animal and plant waste, wastewater treatment plants, runoff from fertilized lawns and cropland, failing septic systems, runoff from animal manure, disturbed land areas and drained wetlands. Phosphorus in water comes in many forms. Both organic and inorganic phosphorus can either be dissolved in the water or suspended (attached to particles in the water column).

Nitrogen is also found in the water column in different forms: as dissolved inorganic nitrogen (nitrate, nitrite and ammonium) and as dissolved or suspended organic nitrogen (complex molecules associated with living, or once living, tissue). Nitrates are the most common form of nitrogen found in our local streams. Together with phosphorus, nitrates in excess amounts can accelerate eutrophication, causing dramatic increases in aquatic plant growth and changes in the types of plants and animals that live in the stream. This, in turn, affects dissolved oxygen, temperature, and other indicators. Excess nitrates can become toxic to warm-blooded animals, particularly babies, at higher concentrations (greater than 10 mg/L) and may also be cancer causing. Sources of nitrates include wastewater treatment plants, runoff from fertilized lawns and cropland, failing on-site septic systems, runoff from animal manure and industrial discharges. Nitrates end up in rivers and streams more quickly than other contaminants like phosphorus, because they dissolve in water more readily and are not adsorbed on soil particles.

Channel Keeper samples are analyzed at UCSB for nitrate, dissolved organic nitrogen, phosphate and suspended organic nitrogen and phosphorus.

Observations made on Stream Team about nutrients: