Science & Monitoring

CWC evaluates watershed heath by assessing biological, physical and chemical factors in monitoring.

This holistic approach helps us determine whether a stream is meeting water quality and habitat standards established by the Clean Water Act and the Federal Endangered Species Act. It also helps us understand what might be impairing the ecosystem and best management practices for its conservation or preservation. This work drives individual stewardship actions and is an example of science driving policy in Santa Cruz County.

Parameters we measure in the field

CWC uses the Water Quality Objectives formulated by Central Coast Ambient Monitoring Program (CCAMP) for these parameters. Water Quality Objectives are the acceptable range for each of the parameters that results in a healthy watershed. CCAMP provides water quality objectives specifically for the Central Coast.

Air and Water Temperature

Water temperature is one of the most important water quality parameters and has direct effects on water chemistry and the functions of aquatic organisms. Temperature influences the dissolved oxygen content of the water; the rate of photosynthesis by algae and other aquatic plants; the metabolic rates of organisms; the sensitivity of organisms to toxic wastes, parasites and diseases; and the timing of reproduction, migration and aestivation of aquatic organisms. Factors which can affect temperature include sunlight energy, seasonal and daily changes, shade, air temperature, stream flow, water depth, inflow of groundwater or surface water, and the color and turbidity (cloudiness) of the water. Other factors include soil erosion, storm water runoff and alterations to stream morphology, substrate and flow. In the Monterey Bay region, the water quality objective is that the water be less than 22 degrees Celsius.


Conductivity is a measure of the ability of the water to conduct an electrical current. This ability is affected by the nutrients and minerals in the water as well as various pollutants. It is also a useful way to measure sea water intrusion as the more salt there is in the water, the higher the conductivity. There is no set water quality objective for the Central Coast area. Generally, the conductivity of rivers in the United States ranges from 50-1500 ųS/cm and inland fresh water studies indicate a range between 150 to 500 ųS/cm for supporting good mixed fisheries (EPA 2003). Industrial waters can range as high as 10,000 ųS/cm (EPA 2003). However, baseline measurements in central coast watersheds are consistently found to be of elevated values normally, up to 1900 ųS/cm and beyond, as so much of the local geology consists of many mineral deposits and uplifted seafloor materials.


Chlorine, as Cl² (molecular chlorine) is highly toxic and it is often used as a disinfectant. High chloride levels can cause human illness and also can affect plant growth. Public drinking water standards require chloride levels not to exceed 250 mg/L. Very high detections in storm drain discharges could be an indicator of industrial waste waters, however low concentrations may indicate a drinking water discharge from a local source.


pH is a measure of how acidic or basic (alkaline) the water is. As the pH decreases, water becomes more acidic and as the pH increases, water becomes more basic. At the extreme ends of the pH scale, (2 or 13) physical damage to gills, exoskeleton and fins occurs. Changes in pH may also alter the concentrations of other substances in water to a more toxic form. In fresh water, increasing temperature decreases pH. Streams containing salmon need to have a pH between 7.0 and 8.5.

Dissolved Oxygen

Dissolved oxygen (DO) refers to the amount of oxygen in water. The dissolved oxygen concentration in water can directly affect reproduction, incubation, changes in species and death of adult and juvenile fish and other organisms. Factors which affect the dissolved oxygen concentration in water include temperature, DO sources such as photosynthesis, DO sinks such as respiration and breakdown of organic material and salinity. Low dissolved oxygen levels usually result from algal blooms, human waste and animal waste. Anadromous fish require high DO levels, particularly during their reproductive phases when it should be as high as 9.0 mg/l or more. The Water Quality Objective minimum for DO for supporting coldwater fish has been set at not less than 7.0 mg/l (Basin Plan).


Turbidity is a measure of the amount of suspended particles in the water. Watersheds in general have a natural turbidity level with inputs from natural erosion, organic decay and algae. Turbidity can be an indicator of erosion, excessive nutrient loading and algal growth. Because of the number of suspended plants and animals (plankton) found within stream systems, turbid water can also be considered natural. The level of turbidity will vary from stream to stream depending on the nutrient loading, geology and stream dynamics. There has been no determination of the natural turbidity level in most of the local watersheds in Santa Cruz County. CWC measures turbidity mainly using Jackson Turbidity Units and uses a water quality objective of less than 20 JTU.


Surfactants and detergents are common contaminants of surface water due to their common usage in every type of washing and cleaning operation. Modern detergents contain more than surfactants. Cleaning products may also contain enzymes to degrade protein-based stains, bleaches to de-color stains and add power to cleaning agents and blue dyes to counter yellowing. Detergent surfactants are made from a variety of petrochemicals (derived from petroleum) and/or oleochemicals (derived from fats and oils). The presence of detergent surfactants in a storm drain system is a strong indicator of run-off or effluent discharges. Detergents lower the amount of oxygen available to fish.

Photo: NOAA Photo Libraries Flickr Creative Commons License 2

Parameters measured in the lab

Levels of nutrients and pathogens in a stream are a commonly accepted indicators of how healthy a stream is. CWC takes water samples for lab analysis for nutrients and pathogens including:


Nitrate is a nutrient that occurs naturally in water bodies and promotes aquatic plant growth. Excessive nutrient levels can lead to algal and aquatic weed growth that in turn depletes the available oxygen in the water column. Runoff containing detergents, fertilizers, animal waste, industrial waste or sewage contributes to elevated nutrient levels as does excess dumping of vegetative material. High levels of nutrients can cause hypoxia and eutrophication in water. The CCAMP Attention Level is 2.25 mg/L. An attention level is a non-regulatory objective that helps us to measure when potential impacts may occur.


Most coliform bacteria originate from the feces of warm-blooded animals and indicate the presence of human sewage or wildlife contamination, as well as feces-born organisms that can cause diseases such as hepatitis A, bacterial meningitis and encephalitis. Total coliform count provides an indicator of pathogen conditions in the water. Testing for “indicator” bacteria monitors the potential presence of disease-causing organisms. Indicator bacteria are types of bacteria not
normally found in high numbers in oceans, rivers or creeks but always found in sources of fecal contamination. Though they are not typically disease-causing organisms themselves, they can be indicative of the presence of such organisms. Studies have shown that when concentrations of indicator bacteria exceed certain levels in waters used for water body contact recreation, individuals exposed to these waters may have a greater chance of getting sick. The EPA Water Quality Criteria of 400 MPN/100 ml is used as the water quality objective.

Ammonia Nitrogen

Ammonia is excreted by animals and produced during decomposition of plants and animals. Its natural breakdown thus returns nitrogen to the aquatic system. It is rapidly oxidized in natural water systems by special bacterial groups that produce the ions of nitrite (NO2), nitrate (NO3), and ammonia nitrogen (NH3–N), which are then used by plants; therefore ammonia is an additional source of nitrogen as a nutrient which may contribute to the expanded growth of undesirable algae and other forms of plant growth that overload the natural system and cause eutrophication. The unionized form of ammonia (NH3) is the preferred nitrogen-containing nutrient for plant growth and is also one of the most important pollutants because it is relatively common, but can be toxic to animals, causing lower reproduction and growth or death to fish and other aquatic life. The water quality objective, according to the U.S. EPA, is less than .025 parts per million.


The orthophosphate test measures the amount of phosphates in the water. Phosphate is a nutrient that is not found in large quantities in streams. As a result, modest increases in it can lead to large changes in the stream conditions. Some effects of phosphates are: accelerated plant growth, algae blooms, low dissolved oxygen and the death of certain fish, invertebrates and other aquatic animals. Human sources of phosphate are wastewater treatment plants, runoff from fertilized lawns and cropland, failing septic systems, runoff from animal manure storage areas, disturbed land areas, drained wetlands, water treatment and commercial cleaning preparations. There is no formal water quality objective for orthophosphate but the CCAMP attention level is 0.12 mg/L.


E.coli is a type of fecal coliform bacteria commonly found in the intestines of animals and humans. E. coli is short for Escherichia coli. The presence of E. coli in water is a strong indication of recent sewage or animal waste contamination, although sewage may contain many types of disease-causing organisms. During rainfalls, snow melts, or other types of precipitation, E. coli and Fecal coliforms may be washed into creeks, rivers, streams, lakes, or groundwater.


Copper is a mineral element; however it is used in many industrial applications. Specific to this program is the fact that surface runoff and stormwater flows pick up copper and zinc from brake and tire wear and other chemicals in vehicle wash wastewater. Concentrations over .025 mg/L are toxic to freshwater fish.

Photo Courtesy of CA Regional Water Quality Control Board