Pay Cut

[coolred]

What is the name of your state (only U.S. law)? Texas

I am an at will employee in a school district who received a 20% cut without notification either verbally or in writing.
Last March, my position was redesignated and my wages never changed. In May, I was told I might have to take a pay cut in the coming school year but the budget was not settled therefore I could not be told how much or when for sure. When I received my pay statement for the September, I learned I had received the 20% cut. I was told that they had chosen to not change my salary when they redesignated me but that with the new school year, they had chosen to do so and pay me what the position actually called for. At the time I was redesignated, I was not told that there was any difference in pay nor when I was told in May about a possible cut was I told the reason. I was led to believe it was because of the budget tightening within the district. This is why I did not question it.
Do I have legal recourse since I was not informed prior to the cut taking place either verbally or in writing ? I feel there was an implied contract when I was allowed by their choice to maintain my current pay status. Please advise. Thanks.