A river with concentration $C_u$ of salt and an upstream flow rate of $Q_u$ receives an agricultural discharge of $Q_a$ carrying $C_a$ of salt. A municipality just downstream withdraws river water and mixes it with pure water from another source to deliver water having no more than salts concentration $C_c$ to its customers.

a$.)$ Is this a steady$-$state or non$-$steady state system?

b$.)$ Conservative or non$-$conservative?

c$.)$ A big storm causes the plant to shut down for a couple of days while the storm water recedes. As the plant manager, you want to know how long it will take to reach a constant concentration of salts to send to the customers. Is this a steady$-$state or non$-$steady state system? Conservative or non$-$conservative?