SAN FRANCISCO (Reuters) - California Public Employees’ Retirement System should maintain its investments in the controversial Dakota Access oil pipeline project in order to exert influence over the companies involved, staff for the largest U.S. public pension fund said on Monday.

File Photo: Calpers headquarters is seen in Sacramento, California, October 21, 2009. REUTERS/Max Whittaker/File Photo

Legislation proposed in California would require CalPERS, a $300 billion fund, to divest from companies involved in the building and financing of the 1,168-mile-long underground pipeline project, which would affect an estimated $4 billion in CalPERS holdings, according to staff.

CalPERS staff said that while divesting stocks of companies involved in the project may reduce stakeholder perception that the fund’s investments contribute to climate change, the move would limit CalPERS ability to change corporate behavior through engagement.

“There is considerable evidence that divesting is an ineffective strategy for achieving social or political goals, since the consequence is generally a mere transfer of ownership of divested assets from one investor to another,” staff said in its recommendation, which was published on its website.

In order to comply with the legislation, CalPERS would have to sell off shares in the pipeline builder Dakota Access LLC and Energy Transfer Partners ETP.N. In addition, the bill calls for divesting from the banks financing the $3.78 billion project. Those banks include Bank of America BAC.N, Wells Fargo WFC.N, JPMorgan Chase JPM.N, and Citibank C.N.

The pipeline would carry crude from Stanley, North Dakota to Pakota, Illinois. It has been the target of intense protests by those concerned that a spill could contaminate water supplies underneath Native American tribal lands.

The CalPERS Investment Committee will meet on Feb. 13 in Sacramento to discuss the bill.

U.S. President Donald Trump has signaled his support for the project, which faced setbacks under the Obama administration. In December the previous government requested a full environmental review by the Army Corp of Engineers.

The U.S. Army secretary could make a decision on the final permit needed to complete the pipeline as soon as Friday, the government’s lawyer told a Washington, D.C., court on Monday.

CalPERS is a frequent target of divestment campaigns. In the past it has pulled cash out of tobacco and firearm companies as well as investments in countries including Iran, Sudan, and South Africa on political grounds.

The legislation, proposed by Assemblymember Ash Kalra of San Jose, also calls on California State Teachers’ Retirement System (CalSTRS) to divest from the pipeline project.

A spokesperson for CalSTRS said the $188 billion fund has not yet taken a position on the legislation.