Notwithstanding any provision of the Government Code, employees of this district may authorize and, upon that authorization, the district may make deductions from their wages and salaries as follows:

1. (a) Pursuant to a collective bargaining agreement with a duly designated or certified labor organization for the payment of union dues, fees, or assessments.
2. (b) For the payment of contributions pursuant to any health and welfare plan or pension or retirement plan.
3. (c) For any purpose for which deductions may be authorized by employees of any private employer.