CES Water Quality & Watershed Management 2 — Questions and Answers
Question 1: Which parameter is used to express the oxygen demand exerted by chemical oxidation of inorganic and organic compounds in water?
- Biochemical Oxygen Demand (BOD)
- Chemical Oxygen Demand (COD) (Correct answer)
- Total Organic Carbon (TOC)
- Dissolved Oxygen (DO)
Correct answer: Chemical Oxygen Demand (COD)
COD measures the amount of oxygen required to chemically oxidize all oxidizable substances in water, including both biodegradable and non-biodegradable compounds.
Question 2: A watershed's baseflow is primarily sustained by which hydrological process?
- Surface runoff
- Interflow
- Groundwater discharge (Correct answer)
- Precipitation throughfall
Correct answer: Groundwater discharge
Baseflow is maintained by groundwater (subsurface) discharge into streams, which sustains streamflow between storm events.
Question 3: The Clean Water Act Section 303(d) requires states to identify waterbodies that fail to meet water quality standards and develop what for each?
- Nonpoint Source Management Plans
- Total Maximum Daily Loads (TMDLs) (Correct answer)
- National Pollution Discharge Elimination Permits
- Watershed Protection Plans
Correct answer: Total Maximum Daily Loads (TMDLs)
Section 303(d) mandates that states list impaired waterbodies and establish TMDLs specifying the maximum pollutant load a water body can receive while still meeting standards.
Question 4: Which type of wetland is most effective at removing nitrate from agricultural runoff through denitrification?
- Tidal saltmarsh
- Riparian wetland (Correct answer)
- Bog
- Playa lake
Correct answer: Riparian wetland
Riparian wetlands situated adjacent to streams intercept agricultural runoff and provide anaerobic conditions ideal for denitrification by soil microbes.
Question 5: In the context of stormwater management, what does LID stand for?
- Large Infrastructure Design
- Low Impact Development (Correct answer)
- Landscape Infiltration Directive
- Lateral Interception Detention
Correct answer: Low Impact Development
Low Impact Development (LID) uses decentralized, small-scale practices like bioretention cells and permeable pavement to mimic natural hydrology.
Question 6: Which index is commonly used to assess the biological integrity of streams using benthic macroinvertebrates?
- Shannon Diversity Index
- Index of Biotic Integrity (IBI) (Correct answer)
- Trophic State Index (TSI)
- Palmer Algal Index
Correct answer: Index of Biotic Integrity (IBI)
The Index of Biotic Integrity (IBI) uses assemblages of benthic macroinvertebrates or fish as biological indicators of stream health and water quality.
Question 7: Carbonate hardness in water is primarily composed of which ions?
- Sodium and chloride
- Calcium and sulfate
- Calcium/magnesium bicarbonates and carbonates (Correct answer)
- Potassium and nitrate
Correct answer: Calcium/magnesium bicarbonates and carbonates
Carbonate hardness (temporary hardness) results from dissolved calcium and magnesium bicarbonates and carbonates, which can be removed by boiling.
CES Water Quality & Watershed Management 2
Which parameter is used to express the oxygen demand exerted by chemical oxidation of inorganic and organic compounds in water?