By Robin Respaut

(Reuters) - The California State Teachers' Retirement System announced on Wednesday that it had calculated the total costs and fees paid to manage its entire investment portfolio, likely the first public pension fund to do so.

CalSTRS found total expenses, including carried interest, reached $1.6 billion in calendar year 2015, or less than 1 percent of the portfolio's $186 billion net asset value.

Presented for first time at Wednesday's meeting of CalSTRS' board, the new cost report marks a milestone among public pension funds to keep tabs on investment expenses and may motivate other funds to track their fees.

It also comes at a time when public pension funds, which manage the retirement benefits of public sector workers and retirees, face growing pressure to disclose the fees that they pay.

The task was not an easy one, however. CalSTRS has over 600 partnership investments, separately managed accounts, joint ventures and co-investments within its portfolio, and there is no industry standard for cost reporting.

As a result, to tally up all of the carried interest, management fees, partnership expenses and portfolio company fees paid by CalSTRS, information had to be collected one investment at a time through direct engagement.

"To the best of my knowledge, this is the most comprehensive review of investment costs," Allan Emkin of Pension Consulting Alliance said at Wednesday's meeting. "On the issue of transparency and disclosure, you will be seen as the new leader."

On Monday, CalSTRS sister fund, CalPERS, announced it had shared about 14 percent of the profit made on private equity investments in the past year with firms managing its private equity asset class.

CalSTRS took fee disclosure a step further, calculating the fees and costs for its entire portfolio. Of the $1.6 billion, approximately 61 percent was external and internal costs, while 39 percent was carried interest, or profits shared.

CalSTRS said it paid an outside firm to compile the data, with the total cost of the project reaching $425,000 plus 1,500 hours of staff time.

Board members said the report was worth the money because it clarified important investment costs.

"This is absolutely fantastic," said Board Member Paul Rosenstiel. "I think it’s very well worth the time and the expenditure."

(Reporting by Robin Respaut in San Francisco; Editing by Lisa Shumaker)