Simplified Hydrologic (Water) Cycle Condensation Rain clouds Transpiration Evaporation Precipitation to land Transpiration from plants Precipitation Precipitation Evaporation From ocean Evaporation From ocean Surface runoff (rapid) Precipitation to ocean Rapid Infiltration and percolation Surface runoff (rapid) Groundwater movement (slow) Ocean storage Fig. 3-24, p. 54

Use of Water Resources Agriculture – 70% world-wide Industrial – in-stream vs. withdrawl Domestic

point source pollution coming from a known source like a pipe easy to monitor easy to address

non-point source pollution nonspecific source diffuse like runoff or atmospheric fallout harder to control accounts for 90% of water pollution today

Types of Pollution

organic from life processes examples include: sewage, animal waste, decomposing vegetation may contain pathogens

inorganic nonliving examples: road salt, dust, silt, clay, from construction

thermal heat pollution example: industrial cooling

toxic poisonous examples: pesticides, heavy metals, chemicals

Clean Water Act Water Classification Class A – potable water, suitable for drinking supply Class B – suitable for full body contact, “fishable, swimmable” Class C – suitable for partial body contact, safe for boating

NSF Water Quality Index a series of 9 weighted tests that yield a single, comprehensive assessment of the overall health of the river our most important assessment tool used world-wide to assess river water quality

Dissolved Oxygen (DO) the highest weighted test sources: photosynthesis and atmospheric mixing levels peak in late afternoon and bottom out just before sunrise – why? the colder the water, the higher the solubility of DO results must be converted to % saturation low DO indicates organic pollution

Fecal Coliform a type of bacteria found in the intestines of warm-blooded animals 2nd most important test not dangerous but high levels may indicate the presence of pathogens expressed as colonies/100ml of water class B water must not exceed 200 col/100ml

pH a measure of water acidity measured on a scale 0 – 14 below 7 is acidic, the lower the number, the more acidic each change of one on the scale indicates a 10-fold change in pH a pH of 7.5 is best for aquatic ecosystems

BOD a measure of the dissolved oxygen used by bacteria when breaking down organic pollution high BOD means low water quality BOD = DO(day1) – DO(day 5)

Temperature measured as temperature change along the river temperature at site – temperature one mile upstream an indication of thermal pollution

Phosphates and Nitrates two important plant nutrients if levels are too high – excessive plant growth and algal blooms occur, and eventually, a drop in DO when plant material decays sources: runoff from farms, lawns; effluent from wastewater treatment plants

Turbidity a measure of water clarity high turbidity means low clarity high turbidity can increase water temps. (lowering DO) and make respiration difficult for aquatic organisms sources: runoff from construction sites, farms, roads

Total Dissolved Solids same water quality issues as with turbidity can be measured with a conductivity meter

Assessing Water Quality Using Benthic Macroinvertebrate “bottom-dwelling, big enough to see with the unaided eye, backbone-less organisms” loosely referred to as “bugs”

Aquatic Insect Metamorphosis Incomplete: egg – nymph – adult complete: egg – larva – pupa - adult

water quality is based on pollution tolerance and/or species diversity pollution tolerance is based on indicator organisms – organisms that are highly sensitive to pollution; their presence is a good sign, their absence, a bad sign species diversity as an indicator of water quality – the greater the number of different types of organisms (richness), and the more evenly distributed (evenness), the better the water quality