Whenever a county, city, town, water-sewer district, or flood control zone district imposes rates or charges to fund stormwater control facilities or improvements and the operation and maintenance of such facilities or improvements under RCW
35.67.020,
35.92.020,
36.89.080,
36.94.140,
57.08.005, or
57.08.081, it may provide a credit for the value of stormwater control facilities or improvements that a person or entity has installed or located that mitigate or lessen the impact of stormwater which otherwise would occur.