Hawaii's Watersheds Help Page


Glossary of Terms

Site Location

Site name: Use letters, numbers, words, anything to name your site but keep it simple and brief. Use your description above to help you choose a good site name. You will use this site name every time you visit this site, so make it easy enough to remember. This is for your reference only. It doesn't have to make sense to anyone else.

Tributary, stream, or canal name: Identify the stream, tributary, or drainage canal you will be working at. Use any map available to help you. (USGS maps are usually the most reliable.) If you are unsure about which stream you are on, try looking on a bridge if one is near by. Stream names are frequently written on bridges. If your site is a drainage ditch, a storm drain, or a small stream or tributary not listed, write "other" and describe it under "description of site".

Major water body it flows into: All Hawaiian tributaries and streams flow into other, larger water bodies. Choose the next largest water body your stream or tributary flows into. If your site is a ditch or storm drain, refer to the City and County storm drain map to see what water body it drain into.

District or neighborhood: Streams can pass through many neighborhoods. Identifying the neighborhood as well as the stream name can help others identify your location.

Description of site: Describe your site with enough detail that someone else could find the site without your help. Use landmarks, buildings, street names, etc. If your site is a storm drain, perhaps there is an address on a nearby house or building to refer to. If your site is away from any infrastructure such as back in a valley accessible only by trail, mention the trail name and do your best to give latitude and longitude.

Intermittent stream: Streams (ditches, canals, gulches,) which have water in them only part of the time.

Perennial stream: Streams (ditches, canals, gulches,) which have water in them all year round.

Glossary of Terms


At your site at time of survey: The concern with weather relates to amount of rainfall which potentially can affect flow, clarity and amount of water in a stream. Note the weather at your site at the time of your survey. Weather rainfall reports are available in the daily newspaper or by calling the local weather service. Definitions of weather conditions established by the Weather Service are: Rain - 1/3" in 24 hours - light steady rainfall. Showers - 1/3" - 1" in 24 hours, intermittent and variable in intensity. Storm - 1" or more rain in 24 hours, usually accompanied by winds.

Anywhere in the headwaters or at your site within the past 48 hours: Stream flow and water clarity is affected not only by the amount of rainfall at your site at the time of your survey but is also affected by rainfall in the headwaters as much as 48 hours prior to your survey time. (Hawaiian streams are designed to get rid of flood waters quickly and usually will return to their normal perennial flow within 48 hours.) Think back or check the weather report to see if it rained/stormed/showered at your site or anywhere in the headwater area of your stream within the past 48 hours.

Glossary of Terms

Stream reach description

Survey reach length: Once you've chosen a site for your regular monitoring, you'll want to expand your familiarity of that site for the streamwalk survey. A 50 meter stretch of stream is ideal. You may want to choose 25 meters upstream from your site and 25 meters down stream from your site, or some other combination depending on accessibility. If a 50 meter walk along the stream is difficult or appears dangerous in any way, limit your reach to an area you can reasonably survey in a safe manner. Whatever length of stream you choose to walk along and observe, this is your "reach" (as opposed to your "site" which is a single, specific spot that you will take water quality measurements from regularly).

Stream type: Pools are deeper than adjacent areas. Riffles and/or runs are flows swift in comparison to surrounding areas. Most Hawaiian streams are pool/riffle in their upper, mountainous portions. On some islands, the lower, coastal portions of streams may flatten out and meander or become straight. Hawaiian streams are rarely braided unless it is a trickle of water flowing over a mud flat or sand.

Habitat alteration (pool/riffle/run present): A variety of flow in relation to depth creates habitat to support fish and invertebrate life. This variety can be seen by looking for pools and riffles. Pools are deeper than adjacent areas. They provide feeding, resting and spawning areas for fish. Riffles and/or runs are flows swift in comparison to surrounding areas. Riffles are shallow and fast water, runs are deep and fast water and pools are slow and deep water.

Glossary of Terms

Stream reach measurements

Average depth to width ratio: This information will give a description of the stream water along your reach. Do not take these measurements if it will disturb habitat, require that you wade in deep water or disturb stream banks. Do not attempt to cross in high flows. If it feels even mildly unsafe, do not try it at all. Remember, this is a screening tool, not the last word.

Take the average of about six measurements of width and depth along your reach. The width is from water's edge to water's edge. The depth is the deepest depth across that width of stream. Choose the location for your measurements according to some unit of measure. For example,if your reach is 50 meters long, take measurements at 0, 10, 20, 30, 40, and 50 meters. This way you are not tempted to skew your results by choosing a spot arbitrarily.

Glossary of Terms


Stream banks: Natural streamside plant cover degraded: Indicate if streamside vegetation is trampled, missing, or replaced by landscaping or cultivation. Introduced plants can also cause damage by dominating an area by crowding out or engulfing all other plants. Introduced plants are difficult to identify from native unless you have a guide, but one indication that an introduced plant may have dominated an area is by looking for many levels or "stories" of vegetation. For example, there may be high trees and thick shade in the upper story with no shrubs in the middle story, and bare, exposed soil in the lower story. Evaluating the environmental degradation of introduced plants can be difficult. Remember, what we are interested in is adequate, but not too dense shade, several levels or "stories" of growth, and enough ground cover to secure the soil.

Banks collapsed/eroded: Note if banks or parts of banks have been washed away or worn down.

Banks artificially modified: Indicate if banks have been artificially modified by construction or placement of rocks, wood or cement supports or lining.

Garbage or junk adjacent to stream: Indicate if human made materials are present.

Glossary of Terms

Stream channel

Mud/silt/sand on bottom/entering stream: Excessive mud or silt entering the stream and clouding the water can interfere with fishes' ability to sight potential prey. It can also clog fish gills and smother fish eggs in spawning areas on the stream bottom. Suspended matter in the water raises water temperature causing further decreases in oxygen. Mud/silt/sand can be an indication of poor construction practices in the watershed: where runoff coming off the site is not adequately contained. It can also be a perfectly normal occurrence, especially if, for example, a muddy bottom is found along a very slow-moving segment or a wetland. Use your best judgment.

Artificial stream modifications: Please note if the stream water has been dammed, dredged, filled, or channelized through culverts or if other large scale activities such as log removal are apparent.

Algae/scum floating/covering rocks: Evidence of algae (very tiny plants that can color the water green or can resemble seaweed) or scum in the water can point to a problem such as an upstream source adding too much nutrient (fertilizer) to the water.

Foam or sheen: This is a bit if a tricky category because this type of thing can be naturally occurring or a problem. For example, an iridescent sheen on the water might be from rotting leaves or it might be from some upstream pollutant. If you are not sure, mark it on the checklist. Try your best.

Garbage or junk in streams: This is your chance to point out very straightforward problems: litter, tires, car bodies, and garbage dumps.

Glossary of Terms


Further Description of Usage

Adjacent land uses: Adjacent land use has a great impact on the quality and state of the stream and riparian areas.
Organic debris or garbage: The purpose is to determine if the stream is being used as a dump site for materials which would not be present naturally. Debris can be anything from a pop can to vegetation brought from somewhere other than the stream corridor.

Livestock in or with unrestricted access to stream: Are livestock present or is there an obvious path that livestock use to get to the water from adjacent fields? Is there streamside degradation that is caused by access? Is animal waste entering the stream?

Actively discharging pipes: Are there pipes which are entering the stream? Please mark even if you cannot find an opening or see matter being discharged.

Ditches: Are there ditches, usually draining the surrounding land which lead into the stream?

Glossary of Terms

Site description

Habitat type (Choose one):
An area of relatively deep slow water in a stream that offers shelter to fish.
Riffle: A shallow, gravely area of stream bed with swift current. Used for spawning by some fishes.
Run: A stretch of fast smooth current, deeper than a riffle.

Width and depth: Measure the width from water's edge to water's edge and the deepest depth across that width at your site. Remember, do not attempt these measurements if it will disturb habitat, require you to wade in deep water, or will result in disturbing stream banks. It feels even mildly unsafe, estimate the depth and width.

Channel cross-section shape: Please check the box which best matches the general shape of the stream channel at your site. If you are unable to see the shape of the bottom and banks, please estimate. You can base your estimate on the flow of water. The slower the water in the middle of the stream, the flatter the bottom.

Stream bottom: Excessive mud or silt entering the stream and clouding the water can interfere with fishes' ability to sight potential prey. It can also clog fish gills and smother fish eggs in spawning areas on the stream bottom. Mud/silt/sand can be an indication of poor construction practices in the watershed: where runoff coming off the site is not adequately contained. It can also be a perfectly normal occurrence, especially if, for example, a muddy bottom is found along a very slow-moving segment or a wetland. Use your best judgment.

Gravel (0.1 - 2 in.), cobbles (2 - 10 in.) and boulders (greater than 10 in.): Stream bottom is made up of material larger than 0.1 inch.

Sand (up to 0.1 inch): Sand is made up of tiny particles of rock. It feels wonderful underfoot.

Silt/clay/mud: This substrate has a sticky, cohesive feeling. The particles are fine. The spaces between the particles hold a lot of water, making the sediments behave like ooze.

Glossary of Terms


Exotic organism populations, organisms which come from other parts of the world which were not original habitants of the Hawaiian Islands, livingin Hawaiian streams are a form of pollution. They degrade the habitat of native fish by competing for food and introducing parasites and deseases which are detrimental to the natives. Some may even preying on juvenile natives or may compete for spawning grounds. Introduced organisms may disrupt the biochemistry of the habitat in other ways such as by comsuming plants which stablize the water chemistry or disturbing the stream bottom making it unsuitable for spawning.

Identify which organisms you saw along your reach. Start with the general class or phylum (fishes, crustaceans, mollusks, or amphibians). Identify further to family, genus, or species to the best of your ability (but don't guess!). If, for example, you see a fish but don't know anything more, check "fish". Stop there if that's all you know. Please don't guess. If you know the fish is a native goby, but don't know what species, check "goby". If you are quite sure you know the species, good for you...check the species!

Another example is with introduced fish. Native gobies are quite distinctive, so if you see a fish and know it isn't a goby, then it is most likely an introduced fish (unless you are very close to the ocean in an estuary type environment with brackish water in which case you may be looking at a aholehole or 'ama'ama). If this is the case, check "introduced fish". Check the species if you know it, else leave it at "introduced fish". Do the same for crustaceans, mollusks, and amphibians.

Glossary of Terms

Streamside vegetation

A description of the presence and type of streamside vegetation provides much information about the stream due to its important role in molding the stream environment. Vegetation acts as a filter for sediment and pollution coming in from the near land. It provides habitat for the many creatures that are dependent on and influence the stream. Branches, logs, and leaves enter the stream from this region. Vegetation also provides shade, which keeps the water cool. On the data sheet mark all the categories that apply.

Conifer: A cone bearing, evergreen tree or shrub (e.g. a pine tree).

Deciduous: A tree which sheds it's foliage at the end of the growing season. In Hawaii, where trees don't go completely bare for the winter, it may be easier to think in terms of "broad-leaf" trees, like a banyon or monkey pod tree, vs. "needle-leaf" trees, like pine trees. Basically, if its not a "needle-leaf" pine, call it deciduous.

Small trees or shrubs: Either conifers or deciduous bushes less than 20 feet high.

Grasses: Any number of plants with narrow leaves, jointed stems and spikes or clusters of inconspicuous flowers. Grass flowers are difficult to recognize so don't let the definition confuse you. By the way, did you know that sugar cane and bamboo are both examples of grasses?

Liana: A woody or herbaceous climbing plant with roots in the ground (e.g. a vine).

Extent of overhead canopy (stream cover): This is the amount of vegetation that overhangs the stream. It focuses on several important values of streamside vegetation: offering protection and refuge areas for fish and other organisms, shading the stream and keeping the water cool, and providing "launching" areas for insects that might fall into the river. Estimate as best you can, about how much of the river is overhung by vegetation, whether it be grasses, shrubs or trees. Please check the category that is appropriate for the current condition of your site.

Extent of ground cover: This is the extent of vegetation growing close to the ground securing the soil. Soil erosion can be a significant source of pollution in the stream. There may be plenty of vegetation along the stream bank, but it may be that thick shade trees, especially introduced species, block sunlight or produce a substance which inhibits the growth of an understory. The exposed soil can erode during heavy rains.

Glossary of Terms

Water Quality Measurements

Ambient temperature: Temperature of the surrounding, curculating air. Measure in degrees Celcsius.

Water temperature: The temperature of the water is very important for water quality. Many of the physical, biological, and chemical characteristics of a stream are directly affected by temperature. For example temperature influences the amount of oxygen that can be dissolved in water, the warmer the water, the less oxygen it holds. Temperature affects the metabolic rates of aquatic organisms. Some organisms are more tolerant of warmer water than others. Native Hawaiian species appear to need cooler waters to survive. They become stressed when water temperatures rise. Introduced species are often much more tolerant of the warmer water. Temperature also affects the sensitivity of organisms to toxic wastes, parasites, and diseases.

Turbidity: Turbidity is the measure of the relative clarity of water: the greater the turbidity, the murkier the water. Turbidity increases as a result of suspended solids in the water that reduce the transmission of light. Suspended solids are varied from clay, silt, and plankton, to industrial wastes and sewage. High turbidity may be caused by soil erosion, waste discharge, urban runoff, abundant bottom feeders (such as carp) that stir up bottom sediments, or algae growth.

NTU stands for Nephelometer Turbidity Unit, and JTU stands for Jackson Turbidity Unit. Both NTU's and JTU's are interchangeable units. They differ only in that their name reflects the device used to measure turbidity. A nephelometer measures the scattering of light by the suspended particles in NTU's. A Jackson tubemeasures the clarity of the water by viewing a candle flame under the tube in JTU's. A Secchi disk has been roughly correlated with JTU's.

Total dissolved solids: That portion of the solid matter found in a water sample that passes through a filter. Dissolved or inorganic materials include calcium, bicarbonate, nitrogen, phosphorous, iron, sulfur, sodium chloride (salt) and other ions found in a water body. Many of these dissolved ions are building blocks of molecules necessary for life. Sources of dissolved solids include leaves and other plant materials, soil particles, and urban runoff.

Total dissolved solids can be measured in parts per million (ppm) or parts per thousand (ppt) depending on the sensitivity of the instrument and the amount of dissolved solids in the water sample.

Dissolved Oxygen: Dissolved oxygen (DO) is essential for the maintenance of healthy water bodies. Most aquatic organisms need oxygen to survive. Some aquatic species are more tolerant of low oxygen conditions than others and have acquired special techniques like gulping air from the surface to get the oxygen they need. Most of the low-oxygen tolerant species are introduced apecies. Native organisms are usually not found in very great numbers in areas of low oxygen. For our purposes, the presence of oxygen is a positive sign, the absence of oxygen is a signal of severe pollution. Waters of consistently high dissolved oxygen are usually considered healthy and stable ecosystems. Sources of dissolved oxygen in water comes from the atmosphere. Waves, wind, and water tumbling vigorously over rocks mix atmospheric oxygen into the water. Algae and rooted aquatic plants also produce oxygen during photosynthesis, but use up oxygen at night in respiration. You may notice in some areas that dissolved oxygen levels rise from mid-morning to late afternoon, reaching its peak late in the afternoon as a result of photosynthesis. Dissolved oxygen levels will fall from sunset to sunrise with the lowest level just before dawn due to plant and animal respiration.

Dissolved oxygen measured in part per million (ppm) can be converted to percent saturation using the graph below. Note: For our purposes, consider mg. per liter as equal to parts per million. Also, you'll need the water temperature in degrees Celsius for the conversion.

Place a straight edge on the figure (below) connecting water temperature and Oxygen (mg. per liter). The straight edge crosses the correct % saturation.

pH: Water (H2O) contains both H+ (hydrogen) ions and OH- (hydroxyl) ions. The pH test measures the H+ ions concentration of liquids and substances. Each measured liquid or substance is given a pH value on a scale that ranges from 0 to 14. Pure deionized water contains equal numbers of H+ and OH- ions, and has a pH of 7. It is considered neutral, neither acidic or basic. If a water sample has more H+ than OH- ions, it is considered acidic and has a pH less than 7. If the sample contains more OH- ions than H+ ions, it is considered basic with a pH greater than 7. It is important to remember that for every one unit change on the pH scale, there is a ten-fold change in how acidic or basic the sample is. Most natural fresh water bodies in the U.S. have a pH between 6.5 and 8.5.Increased amount of nitrogen oxides (NOx) and sulfur dioxide (SO2), primarily from automobile and coal-fired power plant emmissions, are converted to nitric acid and sulfuric acid in the atmosphere. When combined with atmospheric moisture, the it falls to the earth as acid rain or acid snow. Rocks and minerals also determine the pH of the local water. Limestone, for example can make the water alkaline (basic).

Nitrate, Nitrite and Ammonia: Nitrogen is an element needed by all living plants and animals to build protein. In aquatic ecosystems, nitrogen is present in many forms. Nitrogen is most commonly found in its molecular form (N2) which makes up 79 percent of the air we breath. This form, however, is useless for most aquatic plant growth. Blue-green alga, the primary algae of algal blooms, are able to use N2 and convert it into forms of nitrogen that plants can take up through their roots and use for growth: ammonia (NH3) and nitrate (NO-3). As aquatic plants and animals die, bacteria break down large protein molecules into ammonia. Ammonia is then oxidized (combined with oxygen) by specialized bacteria to form nitrates (NO-2) and nitrates (NO-3). Excretions of aquatic organisms are also very rich in ammonia although the amount of nitrogen they add to waters is usually small. High levels of ammonia could indicate an input of human sewage into the waters. Although nitrogen in the form of ammonia and nitrates acts as a plant nutrient, it also causes eutrophication. Eutrophication is characterized by an abundant accumulation of nutients that support a dense growth of plant and animal life, the decay of which depletes the shallow waters of oxygen.

Sources of excess nitrates in the water are: sewage spills or leaks from sewer lines and septic tanks, excessive use of fertilizers on nearby lands, animal waste entering the water from runoff, and green waste dumpage.

Total phosphate: Phosphorous is usually present in natural waters as phosphate (PO4-P). Organic phosphate is part of living plants and animals, thier by-products, and their remains. Inorganic phosphates include the ions (H2PO-2, HPO=4, and PO=4) bonded to soil particles, and phosphates present in laundry detergents. Phosphorus is an essential element for life. It is a plant nutrient needed for growth, and a fundamental element in the metabolic reactions of plants and animals. Plant growth is limited by the amount of phosphorus. In most waters, phosphorus functions as a "growth-limiting" factor because it is usually present in very low concentrations. The natural scarcity of phosphorus can be explained by its attraction to organic matter and soil particles. Any unattached or "free" phosphorus, in the form of inoranic phosphates, is rapidly taken up by algae and larger aquatic plants. Because algae only require small amounts of phosphorus to live, excess phosphorus causes extendive algal growth call "blooms". Algae blooms are a classic symptom of cultural eutrophication.

Phosphorus comes from several sources: human wastes, animal wastes, industrial wastes, and human disturbance of the land and its vegetation. Sewage from leaky sewer lines or septic tanks is one source of phosphorus. Soil erosion contributes phosphorus to rivers. Fertilizers used for crops, lawns and golf courses end up in storm drains and streams when used in excess.

Glossary of Terms

Did you influence the water quality?
If you slid down the bank and caused a landslide of dirt into the water just before you took your water sample, you would have most definitely influenced the water quality. Another way you may have influenced the water quality is by stepping in the stream to take width and depth measurements before taking your water sample. There can be any number of ways you may have effected the water quality at your site. If this is the case, make a note of it, and next time plan to avoid having the same influence.

Is there any evidence of pollution?
Think back, now, on what you've learned about pollution and what the indicators of pollution are. Maybe there is evidence of pollution you never thought of as pollution before, such as an established population of introduced fish or crayfish. Perhaps it is something subtle like a slight rise in water temperature, accumulated fine silt and mud on the stream bottom, or the loss of variable fish habitat. These signs, along with obvious signs such as garbage, are indications of pollution. There are many more way pollution may present itself.

Is there any evidence as to the source of pollution?
Be a detective and document evidence for the cause of the pollution. Don't guess!

If there is no evidence as to the source of the pollution, speculate on some of the possible causes: Here is your chance to make an educated guess and be a little creative. If there is no evidence to the cause of the pollution.

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Help content compiled by Malie Beach & Tom Speitel, HTML by Eric Capers
Last update January 30, 1998 (Speitel)