WATER QUALITY TESTS

What do they all mean?

Dissolved Oxygen - DO

• Measure of how much oxygen is available• Heavily influenced by temperature– Cold water dissolves more than warm water

• 4mg/L or higher is needed to sustain life• Insect larvae and young fish need more DO

than adults – important factor for replenishing biodiversity

• Reduced by organic matter such pet and livestock waste

DO Continued

pH• Measures the [H30+]• Most natural waters have a pH between 6 – 8.5• Photosynthesis increases pH• Cellular Respiration lowers pH• Natural rain has a pH of about 5.6 due to carbon dioxide

making carbonic acid• Metals are more soluble in low pH

– Important to monitor mine run-off (often has a pH of 2 or 3)• pH influences solubility of Ca, P, N, & other elements• Little to no wildlife can live below 4 or above 9• Acid precipitation contributes to issues• Acid waterways can be somewhat remediated by adding

lime (a base)

pH Continued…

pH Continued…

Biological Oxygen Demand• Measures how much oxygen is needed by

aerobic microorganisms• Indicator of the amount of organic waste – Sewage treatment effluent– Stormwater (pets and farmland)– Septic systems– Dead organisms– Industrial effluent

• High BOD lowers DO

Temperature• Varies due to climate and depth• Thermal pollution can lead to water being out

of the tolerance range of native organisms• Testing for thermal pollution– 2 locations 1.6 km apart– Tested at the same time– Should be no more that 2 degrees Celsius apart

Turbidity• Measure of suspended particles– Sand, silt, clay– algae– Plankton

• Caused by– Urban run-off– Bottom dwelling fish (stir up water)– Algae growth– Soil erosion– Heavy storms– High water velocity leading to streambank erosion

Turbidity continued…• Measure of suspended particles– Sand, silt, clay– algae– Plankton

• High turbidity– Increased water temperature due to heat

absorption by particles; leads to low DO– Decreased light penetration for photosynthesis

• Particles clog fish gills, filter feeder siphons, smother fish eggs & benthic organisms

Turbidity Cont…..

• Measured with a turbidity meter or Secchi Disk – what is considered good turbidity depends on water depth, water velocity, and ecosystem type

Fecal Coliform Bacteria

• Bacteria normally found in intestinal tracts of animals (including humans) – Escherichia coli (E. coli) and several other types tested

• Not toxic but indicates that other toxic bacteria and protozoans also found in animal intestinal tracts could be present

• No swimming or eating of shellfish in high level waters

• Can cause water to be smelly and murky

Fecal Coliform Bacteria Cont….

• Caused by – Sewage treatment and wastewater run-off– Animal waste– Septic system issues

• EPA Recommendations– body-contact recreation is fewer than 200

colonies/100 mL– fishing and boating, fewer than 1000 colonies/100 mL– domestic water supply, for treatment, fewer than

2000 colonies/100 mL– drinking water standard is less than 1 colony/ 100ml.

Fecal Coliform Bacteria Cont….

Nitrates

• Caused by– Animal waste– Fertilizers– Human sewage

• Can cause water eutriphication

Nitrate Cont….

• Should be tested in Drinking Water Too– Methemoglobinemia = Blue Baby Syndrome• Reduces the ability for the RBC to carry oxygen

– Linked to non-Hodgkin’s Lymphoma and Stomach Cancers – still disputed by scientists

• Levels in drink levels– Below 10 mg/L (some experts recommend below

1 mg/L for infants 3 months old or younger)

Phosphorus

• Caused by– Animal waste– Detergents– Fertilizers– Industrial Run-off

• Too much causes eutrophication

Macroinvertebrate Tesing

• Uses an index to identify water quality– What type– How many

Other Water Quality Tests

• Alkalinity• Chlorine• Iron• Copper• Iodine• Hardness• Heavy Metals