1. What is the hydraulic residence time of Lake Washington?
2. What is the flow rate through the Montlake Cut? What assumptions do you have to make to do this calculation?
3. How much does the hydraulic residence time of Lake Washington differ between January and August in a typical year?
During a cold and windy night with temperatures predicted to fall below freezing, the Seattle Department of Transportation decides to spread salt on the 520 bridge over Lake Washington to prevent icy roads. They apply 585 kilograms of salt to the road, all of which eventually is washed by the rains into Lake Washington.
4. Ignoring any loses of salt, calculate the salt concentration in Lake Washington as a result of this application. What assumptions are you making?