wages from salarey to hourley employee

Can my employer pay me far less money when going from salary to hourly? I have been on salary for over say 8 years on my check stub it states 1837.51 for 80 hours or two weeks which would bee 22.97 an hour I have always worked 6am to 4pm or 10 hour days and never was paid overtime I questioned this a few times and was told I was exempt. Now they are making changes and I have went from salary to hourly and now punch a clock I am told my hours are now 6 to 5 and will basically be making the same money I asked for a my hourly wage in writing and was given a paper that states my hourly wage is now 16.36 an hour and IM to work no more the 10 hours a day so even taking the 16.36 X a 40 hour week them 24.54 time and a half over time for the other 10 hours a week i will be making less then before my job duties although they now classify them differently are the same I do no less then before I have worked for this company for 19 years. Is this legal or is it a matter of if I want to accept this or look for a nother job Steve