1. All Sewers Lead to the Ocean Exploring and Measuring Stormwater Quality SciREN Coast February 12, 2015 Kellen Lauer and Kathleen Onorevole

2. What is stormwater?

3. Stormwater runoff is generated when precipitation from rain or snowmelt events flows over land or impervious surfaces and does not percolate into the ground (USEPA) impervious surface (sidewalk)

4. What is in stormwater? As stormwater is washed over the land, what might it pick up and carry with it? ●litter and debris ●sediment ●fertilizers/chemicals ●animal waste (especially from wildlife)

6. Water Quality Parameters Scientists measure different parameters that indicate how stormwater runoff affects water quality of the rivers, lakes, or oceans that receive the runoff.

7. What do scientists measure? These are parameters measured by scientists: ●temperature ●turbidity ●nutrients ●dissolved oxygen ●bacteria

9. Temperature ●Runoff is a relatively thin layer of water, so it can heat up substantially as it moves over streets in urban and residential areas. ●Thermal pollution occurs when warm runoff reaches a river or estuary. ●If the stormwater is drastically warmer than the receiving waters, it can heat-shock organisms and potentially cause them to die.

11. Turbidity ●Loose dirt and soil from farms or construction sites can be picked up by stormwater and carried to rivers/estuaries. ●This can increase water turbidity: floating particles suspended in the water (cloudiness). ●Some negative impacts of higher turbidity: o Blocks light from entering the water and reaching aquatic plants. o Covers aquatic plants or clogs the gills of aquatic animals, which can kill them.

13. Nutrients ●Fertilizers are applied to agricultural fields or lawns to help plants grow. They contain nitrogen and phosphorous, which are nutrients. ●When fertilizer is picked up by stormwater runoff, the nutrients ultimately end up in the receiving water, where they can stimulate rapid algae growth, known as eutrophication. ●Some algae can produce toxins that can kill fish and make humans sick.

15. Dissolved oxygen ●Algae don’t have a long lifespan, so they will die within a couple of days. ●Soon after a large algae bloom (eutrophication event), all the algae rapidly die and settle onto the bottom. ●They then decompose, which removes oxygen from the water. Fish cannot breathe without oxygen dissolved in the water, causing them to die. When large numbers of fish die at once, it’s termed a “fish kill.”

17. Bacteria ●Bacteria and pathogens (oftentimes coming from fecal matter) are delivered into receiving waters by stormwater runoff. ●They have the ability to make people sick if they swim in contaminated water or eat shellfish which have filtered contaminated water. ●Bacteria have a larger effect on human health than environmental health.

18. Water quality standards Because bacteria concentrations that are too high can make people sick, there are safe water quality standards set by the U.S. Environmental Protection Agency.

19. Water quality standards Water samples are tested for bacteria concentrations on a regular basis. If the concentrations are higher than the safe water quality threshold, the waters will be closed to swimming or shellfish harvesting until bacteria concentrations are reduced to safe levels.

20. How do we fix the problem? Can you think of ways to cut down on pollutants in stormwater?

21. Oysters and Water Quality Remember that stormwater runoff can contain a lot of nitrogen, and too much nitrogen can cause algae blooms.

22. Oysters and Water Quality ●Oysters can help remove some of this extra nitrogen from water. This process is called denitrification. ●After denitrification, there’s less nitrogen in the water for algae to use to grow. ● Chemical reaction: NO 3 → NO 2 → NO → N 2 O → N 2

23. Oysters and Water Quality ●Many coastal towns are restoring oyster reefs that had been lost through overharvesting or disease o Scientists think that the present area of oyster habitat in estuaries is ⅓ of what it was in the mid-1800s

24. Conclusions In today’s modern society, we will never be able to get rid of all the negative impacts of stormwater. However, certain natural ecosystems have the ability to reduce negative consequences of stormwater runoff. We can alleviate water quality problems by restoring ecosystems such as oyster reefs.