Did Obama EPA department hide information by using private email accounts?

Could it be used to legally challenge the regulations that are issued if it implies that the proper process wasn't used to implement regulations?  So will the Obama administration speak out on whether they disapprove of this activity?  From The Hill:

Republicans on the House Science, Space and Technology Committee have launched a probe into whether Environmental Protection Agency (EPA) Administrator Lisa Jackson has been conducting official business using secret email accounts.The lawmakers said the practice may violate transparency and record-keeping laws. . . .
"The use of these accounts could seriously impair records collection, preservation, and access, therefore compromising transparency and oversight," the Republicans wrote in a letter to Jackson.
The lawmakers demanded that Jackson turn over all records related to "Richard Windsor" and all other aliases used by senior EPA officials. . . .