(LETTERHEAD OF DELOITTE & TOUCHE LLP) Exhibit 23(a) INDEPENDENT AUDITORS' CONSENT We consent to the incorporation by reference in this Registration Statement of Westbank Corporation on Form S-8 of our report dated January 25, 2002, appearing in the Annual Report to Stockholders and incorporated by reference in the Annual Report on Form 10-K of Westbank Corporation for the year ended December 31, 2001. /s/ DELOITTE & TOUCHE LLP Stamford, Connecticut July 22, 2002 10