Wisconsin's public sector unions continue to struggle to retain members in the wake of Gov. Scott Walker's reforms, new Labor Department filings indicate. American Federation of State, County and Municipal Employees District Council 48, one of the union's four main branches in the state, has seen its membership slip to just 3,405 by the end of 2013. It had more than 9,000 members as recently as 2010.

Walker's reforms ended the state's practice of automatically deducting membership dues from public sector workers on behalf of their union and for the first time, allowed those workers to opt out of being union members. Effectively, he applied right-to-work rules to those unions. The reforms also required the unions to submit to annual recertification votes and limited collective bargaining to just wages.

Many members took advantage of those reforms and left. Council 48's membership fell to just over 6,000 in 2011, the year the reforms were enacted. The following year, it fell to 3,498. The only good news for the union is that 2013's losses, just 93 members, weren't as steep as the previous years.

The reforms also had a serious impact on the union's finances. It reported total assets of over $2 million in 2010, but just $778,855 for 2013. A spokesperson for the council could not be reached for comment.

The overall number of public sector union members in the Badger State is not clear, though. Current data for AFSCME's other three main state branches was not available. Only private sector unions are required to make the federal filings, called "LM-2s," which include their membership numbers. Council 48 had to file one because while it mostly represents state employees, it does also have some private sector members.

Another branch, AFSCME Council 40, has made filings in the past. It reported having 31,730 members at the end of 2010. That dropped to 29,777 the following year and was just 20,488 by the end of 2012.

Overall union membership in the state is up, though. The Labor Department reported in January that it was 12.3 percent, up from 11.2 percent the year before. These numbers include public and private sector members.