Domestic waste water in mid-county is currently discharged into individual septic tanks which drain to groundwater system. The discharge of waste water into the aquifer has produced an increase in nitrate concentration in the aquifer and in the slough (hydraulically connected to the aquifer).

A sewer construction program has been proposed as one way of controlling aquifer and slough pollution. Develop a water quality balance analysis to evaluate the effectiveness of the sewer construction program. In particular, estimate the solute response time for nitrate or when will the magnitude of nitrate flux / concentration into the slough decreases to approximately 40% of that original flux after changing to a sewer system.