Overview: This page describes the Science Olympiad Water Quality event (Divisions B & C), its
topics (rotating freshwater vs. marine/estuary), required skills, and core water-quality concepts
and tests.
โ Event basics
โ Covers physical, chemical, and biological water properties.
โ Topic rotates; 2026 = Freshwater; recent years included Marine/Estuary.
โ Participants: 2; 50 minutes; bring a salinometer and allow resources.
โ Biological indicators
โ Freshwater macroinvertebrate classes (1โ5) and nuisance species.
โ Marine/estuary coral reef indicator species grouped by region and stressors.
โ Human impact and treatment
โ Wastewater: septic systems and treatment plants.
โ Primary: screening, grit removal, sedimentation (sludge/scum).
โ Secondary: aeration, bacterial decomposition, clarification, disinfection.
โ Tertiary: nutrient removal and advanced filtration.
โPotable water: coagulation โ flocculation โ sedimentation โ filtration
โ disinfection โ distribution.
โ Core ecology concepts
โ Species interactions: competition, mutualism, predation, parasitism, etc.
โ Food webs, trophic levels, autotrophs/heterotrophs, decomposers.
โ Population ecology: survivorship curves, r/K selection, life tables.
โ Nutrient cycles: carbon, nitrogen, phosphorus, sulfur.
โ Key water-quality parameters (what to measure and why)
โ Salinity: ppt classification, ecological effects, and salinometer construction
(straw/clay hydrometer example).
โ pH and alkalinity: acidity/basicity, buffering, and ecological thresholds.
โ Nutrients: phosphates and nitratesโsources and eutrophication risk.
โ Turbidity and total/suspended/dissolved solids: measurement methods (Secchi,
NTU, TSS/TDS) and effects.
โ Dissolved oxygen (DO) and BOD: oxygen supply, biological demand, and
ecosystem impact.
โ Temperature: thermal pollution effects and DO interactions.
โ Fecal coliform: health risk, sources, and testing (colonies per 100 mL).
โ Analysis and competition notes
โ Students should know acceptable ranges for estuary systems and drivers of
parameter changes.
โ The Water Quality Index should not be used in the event.
โ Salinometer task: build a device to measure 1โ10% salinity; regional and state
accuracy requirements listed.
