REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM


The Board of Directors and Shareholders
RiverSource Special Tax-Exempt Series Trust
RiverSource California Tax-Exempt Trust:

In planning and performing our audits of the financial statements of
RiverSource Massachusetts Tax-Exempt Fund, RiverSource Michigan
Tax-Exempt Fund, RiverSource Minnesota Tax-Exempt Fund, RiverSource New
York Tax-Exempt Fund and RiverSource Ohio Tax-Exempt Fund (funds within
RiverSource Special Tax-Exempt Series Trust), and RiverSource California
Tax-Exempt Fund (a series of RiverSource California Tax-Exempt Trust) for
the period from June 30, 2006 to August 31, 2006 in accordance with the
standards of the Public Company Accounting Oversight Board (United
States), we considered their internal control over financial reporting,
including control activities for safeguarding securities, as a basis for
designing our audit procedures for the purpose of expressing our opinion
on the financial statements and comply with the requirements of Form
N-SAR, but not for the purpose of expressing an opinion on the
effectiveness of the Funds' internal control over financial reporting.
Accordingly, we express no such opinion.

The management of RiverSource Special Tax-Exempt Series Trust and
RiverSource California Tax-Exempt Trust are responsible for establishing
and maintaining effective internal control over financial reporting. In
fulfilling this responsibility, estimates and judgments by management are
required to assess the expected benefits and related costs of controls. A
company's internal control over financial reporting is a process designed
to provide reasonable assurance regarding the reliability of financial
reporting and the preparation of financial statements for external
purposes in accordance with U.S. generally accepted accounting
principles. Such internal control includes policies and procedures that
provide reasonable assurance regarding prevention or timely detection of
unauthorized acquisition, use or disposition of a company's assets that
could have a material effect on the financial statements.

Because of inherent limitations, internal control over financial
reporting may not prevent or detect misstatements. Also, projections of
any evaluation of effectiveness to future periods are subject to the risk
that controls may become inadequate because of changes in conditions, or
that the degree of compliance with the policies or procedures may
deteriorate.

A control deficiency exists when the design or operation of a control
does not allow management or employees, in the normal course of
performing their assigned functions, to prevent or detect misstatements
on a timely basis. A significant deficiency is a control deficiency, or
combination of control deficiencies, that adversely affects the company's
ability to initiate, authorize, record, process or report external
financial data reliably in accordance with U.S. generally accepted
accounting principles such that there is more than a remote likelihood
that a misstatement of the company's annual or interim financial
statements that is more than inconsequential will not be prevented or
detected. A material weakness is a significant deficiency, or combination
of significant deficiencies, that results in more than a remote
likelihood that a material


misstatement of the annual or interim financial statements will not be
prevented or detected.

Our consideration of the RiverSource Special Tax-Exempt Series Trust and
RiverSource California Tax-Exempt Series Trust internal control over
financial reporting was for the limited purpose described in the first
paragraph and would not necessarily disclose all deficiencies in internal
control that might be significant deficiencies or material weaknesses
under the standards established by the Public Company Accounting
Oversight Board (United States). However, we noted no deficiencies in the
RiverSource Special Tax-Exempt Series Trust or RiverSource California
Tax-Exempt Series Trust internal control over financial reporting and
their operation, including controls for safeguarding securities, that we
consider to be a material weakness as defined above as of August 31,
2006.

This report is intended solely for the information and use of management,
the Board of Directors of RiverSource Special Tax-Exempt Series Trust and
RiverSource California Tax-Exempt Trust, and the Securities and Exchange
Commission and is not intended to be and should not be used by anyone
other than these specified parties.



                                            /s/ KPMG LLP
                                            ------------
                                                KPMG LLP



Minneapolis, Minnesota
October 20, 2006