Warmup 10/25/12 If family members living in the house find nitrates in their drinking water (which comes from the well), where should they look for the source of the contamination?

Warmup 10/26/12 We’re halfway through the semester! Which topic has been your favorite to learn about and why? Least favorite? Which activity/lab has been your favorite and why? What will you change about your study habits in this class for next quarter? What would you like me to change about this course?

Non Point Source Pollution Effects on water quality

Impervious Surfaces Humans in towns and cities impact urban streams by creating large amounts of impervious surfaces. Impervious surfaces include roads, parking lots, rooftops, sidewalks, and driveways

Relationship between Impervious Cover and Storm runoff

Run Off Since a large portion of the rainfall in urban areas no longer penetrates into the ground, it is intentionally routed to storm drains and enters directly into urban streams as run off.

Storm Runoff

Urban Runoff Runoff entering urban streams can carry all kinds of chemicals and pollutants with it e.g., motor oil, pet waste, lawn fertilizers, and even sewer leakage).

Sediment and Turbidity Perhaps the biggest impact of runoff entering urban streams, though, is the increased rate of storm flow. When an urban stream experiences rain, the flow rate is much higher than in a natural stream, and this high flow rate brings with it energy that can erode stream banks and push sediment into the water, increasing turbidity.

Lower base flow Urban streams may also have lower base flow rates than natural streams. This means that organisms in urban streams must be able to cope with both fast flows just after storm events and slow flows between storm events.

Water Table Over time, the faster storm flow rates and resulting erosion in urban streams can lead stream channels to become deeper and more incised. The water table then typically becomes lower because of the deeper, narrower streambed. The result is a “floodplain” that rarely floods. A riparian zone where tree roots cannot reach the water table, and riparian trees that die of drought stress. When riparian trees die, urban streams receive more direct sunlight and experience increased temperatures and greater variation in temperature.

Water table shift and decrease riparian area

Water Table Water Table Over time, the faster storm flow rates and resulting erosion in urban streams can lead stream channels to become deeper and more incised. The water table then typically becomes lower because of the deeper, narrower streambed. The result is a “floodplain” that rarely floods. A riparian zone where tree roots cannot reach the water table, and riparian trees that die of drought stress. When riparian trees die, urban streams receive more direct sunlight and experience increased temperatures and greater variation in temperature.

Activity: A Grave Mistake Using your data of arsenic levels, map the levels in the town. If you need more data, you can dig a test well in other locations. To do so, ask me! (If I don’t have data for that location, ask for another location.)

Arsenic in ground water Sources Natural: bedrock Human induced: pesticides, graves (embalming 1880-1910)

Arsenic Poisoning Acute: large quantity at one time Vomiting, diarrhea, even death Chronic: poisoning over longer period of time Skin lesions, numbness

Activity: Dilemma Derby Read your dilemma card. On your sheet of paper: SUMMARIZE your dilemma/problem DECIDE which option your group thinks is best EXPLAIN why your group thinks that’s the best option. (Think consequences) Choose a new dilemma card and repeat (and repeat and repeat)