What is a Watershed?

• An area of land, from ridge top to ridge top, that collects, stores, and releases water to a common point, such as a river or a lake

What’s in a Watershed?

Streams RiversLakes WetlandsHills Mountains

Farms CitiesHousesHumansAnimalsPlants

Watershed Components

Watershed Processes

PrecipitationEvaporationInfiltrationRunoffErosion

Impacts on Watershed

Land UsePollution

Too much of a good thingPoint SourcesNon-Point Sources

ErosionNaturalHuman-accelerated

Watershed Study

PHYSICALWidth Water ColorDepth StreambankBottom Materials Shading (canopy)Soils/Rocks FlowTemperature DamsTurbidity Flow Alterations

BIOLOGICALBacteria AnimalsViruses FishPlankton PlantsMacroinvertebrates Algae

CHEMICALpH AlkalinityDissolved Oxygen BODConductivity ToxicsPhosphorus NitratesChlorine/Chloride Heavy Metals

“Water Quality”

Water shed to stream = easier to measureWater Quality is primarily chemistry“Quality” is a value judgement based on intended use

Drinking waterRecreationAquatic life

Water Quality Parameters

TemperatureDissolved OxygenBODpHAlkalinityTurbidity/Total Suspended SolidsPhosphorusNitrateChlorine/Chloride

Temperature

Most aquatic organisms are poikilothermic - don’t internally regulate their body temp The rate of many chemical reactions increases at higher temperatures.Oxygen solubility as temperature Loss of riparian shadingWater inputs (Industrial, Groundwater, etc)Weather Turbidity can temperature

Temperature

Measure of heatTemperature scalesEquipment

Data LoggersThermometers

0°C

32°F

100°C

212°F

Dissolved Oxygen

Photosynthesis ( DO)Atmospheric Re-aeration ( DO)Inflow of oxygenated water ( DO)Respiration ( DO)Biochemical Oxygen Demand ( DO)Nitrification (NBOD) NH3 + O2 = NO3

Dissolved Oxygen

Measure of O2 in water

BOD is difference in DO after 5 daysMeasures oxygen-consuming waste present in water

EquipmentDO meterWinkler titration

pH

Organisms have optimal range (6.5 – 8.5)pH controls availability and “speciation” of many chemicalsPhotosynthesis ( pH)Respiration ( pH)“Acid” Rain (pH < 5.6) caused by NOx and SO2

Industrial Wastewater

pH

Measure of hydrogen ion concentrationEquipment

Color indicatorspH Meter

Alkalinity

Calcium carbonate CaCO3 – lime

Carbonic acid – CO2 + H2O = H2CO3

Bases (OH-)Phosphate (PO4

3-)

Wastewater Stormwater Runoff

Alkalinity

Measure of acid buffering capacityEquipment

Acid (H2SO4) titration

pH endpoint (~pH 4.5) can be measured using color indicator or pH meterBromcresol Green-Methyl Red – changes from green to pink at pH 4.5

pH

Drops acid added

7.0

4.5

Turbidity/Total Suspended Solids

Caused by sediment, algae and organic materialInhibits plant growthDecreases visibility for visual feedersInhibits gill respirationSmothers eggs

90 Light Detector

Transmitted Light Detector

Light sourceTungsten Lamp

Lens Sample Vial

Turbidity

Measure of light scatteringEquipment

Secchi diskTurbidity tubeTurbidimeter

Total Suspended Solids

Measure of solids in waterEquipment

Filter funnel1.0 m filterDrying ovenDessicator

Glass Fiber Filter(0.45 or 1.0 μm)

Total suspended solids (TSS)

Water sample

Total dissolved solids (TDS)

Nutrients

Phosphorus and Nitrogen - essential “macronutrients” for plants and animalsUsually not obtained from air“Limiting nutrients”Excess can lead to Eutrophication

Phosphorus

Soluble Reactive Phosphorus (SRP)aka orthophosphorus (PO4

3-), but due to pH, most will be HPO4

2- or H2PO4-

“bio-available” P

Total PhosphorusSRP + bound phosphorusP adsorbs to surfaces of organic & inorganics (suspended sediment)P absorbs into large organic & inorganics

Nitrogen

Ammonia (NH3) and nitrate (NO3) are 2 most common formsAmmonia can be NH3 (toxic) or NH4

+ (ammonium)

Nitrate is VERY soluble & preferred N source for plants.Nitrate toxic >10 mg/L

Chlorine and Chloride

Chlorine (Cl2)

Doesn’t occur naturallyUsed for water treatmentGood indicator of human impacts

Chloride (Cl-)Naturally present in saltsCan be an indicator of human impacts

Nutrient Measurement

Colorimetry - Color ChangeColorimeter quantifies color change

Light Detector - Absorbance

Light sourceTungsten Lamp

Lens Sample Vial

Filter