Water Quality & Management Flashcards

Which federal program under the Clean Water Act provides grants to states for construction of publicly owned treatment works (POTWs)?

Answer: Clean Water State Revolving Fund (CWSRF)

The CWSRF provides low-interest loans and grants to municipalities for wastewater infrastructure, funded by federal capitalization grants matched by state contributions.

Thermocline stratification in a reservoir creates a water quality concern because the hypolimnion (bottom layer) may become:

Answer: Depleted in dissolved oxygen and enriched in reduced metals like iron and manganese

The hypolimnion is isolated from surface reaeration; bacterial decomposition depletes its oxygen, releasing reduced forms of iron, manganese, and phosphorus.

A hydrographer is tasked with computing a storm-event pollutant load. The correct calculation is:

Answer: Instantaneous concentration × instantaneous flow, summed over the storm duration

Event mean load is computed by multiplying concurrent concentration and flow at each time step and integrating (summing) over the storm hydrograph.

Which physical process is primarily responsible for removing suspended sediment from stormwater runoff in a detention pond?

Answer: Gravitational settling (sedimentation)

Detention ponds reduce flow velocity and allow time for gravitational settling of suspended particles before the water is released.

Which water quality issue is specifically addressed by a 303(d)-listed impairment for 'pathogens'?

Answer: Elevated bacteria concentrations that make water unsafe for swimming or shellfish harvesting

Pathogen impairments refer to elevated levels of fecal indicator bacteria that close beaches, shellfish beds, or other contact-recreation uses.

The concept of 'antidegradation' in US water quality policy requires that:

Answer: Existing water quality levels be maintained and protected, with high-quality waters given special protection

Antidegradation policy prohibits lowering water quality below current levels and requires justification before allowing any new or increased degradation.

When interpreting a longitudinal water quality profile in a river, a hydrographer observes rising nitrate and declining dissolved oxygen at a downstream station. The most likely cause is:

Answer: Agricultural drainage or wastewater inputs adding nutrients that drive biological oxygen demand

Nutrient-rich agricultural or wastewater inputs stimulate microbial decomposition that consumes oxygen while adding nitrate to the water column.