Is Juanita Creek in Danger? Effects of Rain and Runoff on the pH of Juanita Creek

What makes the rain acidic?  Natural acidity CO 2 (g) + 2H 2 O(l)  H 3 O + (aq) + HCO 3 - (aq)CO 2 (g) + 2H 2 O(l)  H 3 O + (aq) + HCO 3 - (aq)  Pollution SO 2, SO 3, NO x are produced by factories & car exhaustSO 2, SO 3, NO x are produced by factories & car exhaust SO 2 + H 2 O  H 2 SO 3 (sulfurous acid)SO 2 + H 2 O  H 2 SO 3 (sulfurous acid) SO 3 + H 2 O  H 2 SO 4 (sulfuric acid)SO 3 + H 2 O  H 2 SO 4 (sulfuric acid) NO x + H 2 O  HNO 2 + HNO 3 (nitric acid)NO x + H 2 O  HNO 2 + HNO 3 (nitric acid)  This is called WET deposition.

What about the runoff?  Acidic particles in the dust and air Same factory & car-produced pollutants Same factory & car-produced pollutants Sticks to buildings, trees, roads, etc. Sticks to buildings, trees, roads, etc. Washed off by rain; collects in runoff Washed off by rain; collects in runoff  This is called DRY deposition.

A pictoral view

Initial Model pH of creek Rain Run-off 2 ] air [CO 2 ] air Air pollutants Dust & deposited particles Temperature

Why do we care?  Juanita Creek is a coho and chinook salmon run where fish come to spawn Most fish die at pH values between 4.5 & 5.0 Most fish die at pH values between 4.5 & 5.0  Insects that salmon feed on are affected by changes in pH  Algal growth is needed for the insects’ food.

Assumptions  Biological contributions to pH are minor in the winter Temperature Temperature Scouring effect of moving sediments during rainstorms (based on background reading) Scouring effect of moving sediments during rainstorms (based on background reading)  The section of the creek sampled is similar to other portions of the main stem creek Water chemistry Water chemistry Loading Loading

Assumptions, con’t.  Juanita Creek does not have a major buffering system (based on background reading)

Methods  Samples were taken from a portion of the main stem of Juanita Creek for 26 days. 5 mile long drainage creek in north Kirkland; empties into Lake Washington 5 mile long drainage creek in north Kirkland; empties into Lake Washington Drainage for ~4000 acres Drainage for ~4000 acres  Collected water and soil samples daily at 4:30 pm Water from midstream (assuming I could reach it!) Water from midstream (assuming I could reach it!) fine and coarse sand (averaged) fine and coarse sand (averaged)  Collected rain water when available

Methods, con’t.  Tested pH using a pH meter & electrode Calibrated pH meter using standards Calibrated pH meter using standards pH 4.01 & pH 7.01pH 4.01 & pH 7.01  Checked online for daily precipitation Local weather station Local weather station XDailyHistory.asp?ID=KWAKIRKL1 XDailyHistory.asp?ID=KWAKIRKL1 XDailyHistory.asp?ID=KWAKIRKL1 XDailyHistory.asp?ID=KWAKIRKL1  Recorded and manipulated data in Excel

What did I find? Amount of Rainfall pH of rainfall Amount of Rainfall pH of rainfall

pH Data pH Data  pH of water  pH of soil

Is the Creek in Danger?  Is the creek pH changing with rainfall?  Is the soil pH changing with rainfall?

Final Claim– NO!  Appears to be some correlation between amount of rainfall and pH in Juanita Creek, although not to any great extent Evidence: Graphs show that creek pH drops slightly with average to high amounts of rain Evidence: Graphs show that creek pH drops slightly with average to high amounts of rain Evidence: Although to a lesser extent, soil pH also drops slightly with average to high amounts of rain Evidence: Although to a lesser extent, soil pH also drops slightly with average to high amounts of rain

 pH never dropped near or below safe levels for fish Evidence: lowest pH reached for either creek or soil was 6.45 (Nov. 15). This is well above harmful levels for fish and other organisms. Evidence: lowest pH reached for either creek or soil was 6.45 (Nov. 15). This is well above harmful levels for fish and other organisms.  At least in the winter, if appears as if the creek is healthy.  At least in the winter, if appears as if the creek is healthy.

Revised Model pH of creek RainRun-off 2 ] air [CO 2 ] air Air pollutants Dust & deposited particles Temperature Sunshine Natural Wetland Filtration? Manmade Barriers to Runoff? X X

Future Considerations  What would the data look like in the summertime?  Have recommended runoff filtration devices (ex. hay bales) been put in place? How much of an impact do these make? How much of an impact do these make? The questions are still many!!