The U.S. Education Department said it is investigating Denver Public Schools for alleged discrimination after the district converted a girl’s restroom on the second floor of East High School into an all-gender restroom while leaving the other bathroom exclusively for male students.

The U.S. Department of Education said on Tuesday it was investigating whether the Denver school system discriminated against women and girls by converting a female bathroom into one for all genders. Gender in schools has been a key issue for U.