Source Water Characteristics Flashcards

What is the primary reason water treatment plants conduct continuous source water monitoring rather than grab sampling alone?

Answer: Source water quality can change rapidly and continuously, especially in surface water

Surface water quality can shift dramatically within hours due to storms, algal die-offs, or upstream events, making continuous monitoring essential for timely treatment adjustments.

Cryptosporidium and Giardia cysts are of greatest concern in which type of source water?

Answer: Surface water or groundwater under the direct influence of surface water (GWUDI)

Cryptosporidium and Giardia are shed by warm-blooded animals and enter surface water through runoff; GWUDI sources share this vulnerability.

A sudden drop in source water pH combined with increased conductivity after a heavy storm most likely indicates:

Answer: Acid runoff and dissolved minerals entering from the watershed

Storm runoff can carry acidic compounds and dissolved minerals from soils and roads, lowering pH and raising conductivity in the receiving water body.

Which characteristic distinguishes a confined aquifer from an unconfined aquifer in terms of source water protection?

Answer: Confined aquifers are overlain by an impermeable layer, offering greater protection from surface contamination

The impermeable confining layer above a confined aquifer restricts infiltration of surface contaminants, generally providing better natural protection than unconfined aquifers.

What is the significance of measuring total hardness in source water for a treatment operator?

Answer: Hardness determines scale formation potential, softening requirements, and coagulation chemistry

Total hardness, caused by calcium and magnesium ions, affects scale deposition, corrosion potential, coagulant selection, and softening process design.

What does a Secchi disk measurement indicate about source water quality in a reservoir?

Answer: Water clarity/transparency as a surrogate measure of turbidity and algal density

The Secchi disk depth — how deep the disk remains visible — is a simple field method to estimate water transparency, which correlates with turbidity and algal growth.

When evaluating a new surface water source, which data set is most critical to collect over a minimum one-year period before selecting treatment processes?

Answer: Comprehensive seasonal water quality profile including turbidity, TOC, microbiology, temperature, and chemical parameters

Source water quality varies significantly by season; a full year of comprehensive data captures spring runoff, summer algal growth, fall turnover, and winter low-flow conditions needed to properly design treatment.