CES Water Quality & Watershed Management 3 — Questions and Answers
Question 1: Under the NPDES permit system, a municipal separate storm sewer system (MS4) operator is required to implement which primary management approach?
- Secondary treatment of all stormwater before discharge
- Six minimum control measures for stormwater management (Correct answer)
- Installation of retention ponds on all properties
- Zero discharge of stormwater to surface waters
Correct answer: Six minimum control measures for stormwater management
Phase I and Phase II NPDES permits for MS4s require implementation of six minimum control measures including public education, illicit discharge detection, and construction site controls.
Question 2: Eutrophication in lakes is most directly driven by excess inputs of which nutrients?
- Iron and manganese
- Nitrogen and phosphorus (Correct answer)
- Calcium and magnesium
- Potassium and sulfur
Correct answer: Nitrogen and phosphorus
Excess nitrogen and phosphorus stimulate algal blooms that lead to oxygen depletion, reduced light penetration, and degraded aquatic habitat in a process called eutrophication.
Question 3: Which physical characteristic of a watershed most directly influences the flashiness of its storm response?
- Average annual precipitation
- Percentage of impervious surface cover (Correct answer)
- Soil pH
- Vegetation species diversity
Correct answer: Percentage of impervious surface cover
High percentages of impervious surface reduce infiltration, causing rapid runoff concentration that produces sharp, high-amplitude storm hydrographs (flashy response).
Question 4: In drinking water treatment, the primary purpose of coagulation and flocculation is to remove which contaminants?
- Dissolved gases and volatile organic compounds
- Suspended particles, colloids, and turbidity (Correct answer)
- Nitrates and fluoride
- Heavy metals through ion exchange
Correct answer: Suspended particles, colloids, and turbidity
Coagulation and flocculation destabilize and aggregate colloidal and suspended particles so they can be removed by subsequent sedimentation and filtration.
Question 5: Which federal regulation establishes maximum contaminant levels (MCLs) for public drinking water supplies in the United States?
- Clean Water Act
- Safe Drinking Water Act (SDWA) (Correct answer)
- Resource Conservation and Recovery Act
- Comprehensive Environmental Response, Compensation, and Liability Act
Correct answer: Safe Drinking Water Act (SDWA)
The Safe Drinking Water Act (SDWA) of 1974 authorizes EPA to set MCLs and treatment technique requirements for public water systems to protect public health.
Question 6: A riparian buffer strip is most effective when it contains which type of vegetation arrangement?
- Mown grass only to allow easy access
- Monoculture of fast-growing willows
- Multi-layered mix of grasses, shrubs, and trees (Correct answer)
- Annual crops planted in rotation
Correct answer: Multi-layered mix of grasses, shrubs, and trees
Multi-layered riparian buffers with grasses, shrubs, and trees provide maximum pollutant removal, bank stabilization, and wildlife habitat through diverse root structures and canopy.
Question 7: The concept of 'first flush' in stormwater management refers to which phenomenon?
- Initial dilution of pollutants when rain begins
- Disproportionately high pollutant concentrations in early stormwater runoff (Correct answer)
- First overflow event from a combined sewer system annually
- Initial treatment cycle in a constructed wetland
Correct answer: Disproportionately high pollutant concentrations in early stormwater runoff
The first flush effect describes the phenomenon where the initial portion of stormwater runoff carries the highest concentrations of accumulated pollutants from impervious surfaces.
CES Water Quality & Watershed Management 3
Under the NPDES permit system, a municipal separate storm sewer system (MS4) operator is required to implement which primary management approach?