How to select largest value for each date?

I have my data arranged in 4 columns as shown below (sample data). I need the Excel to find the largest value for each date and write them somewhere along with those dates. For example, the Excel should write in the 5th column (E) below two dates and values based on the sample data I listed below -

4/1/2007 - 0.044
4/2/2007 - 0.055

I have about 17-18 values for each date between 4/1/2007 and 10/31/2007.

Thanks.

Sample Data
========================================
A B C D
--------- ---------- ---- -----
Date SITE POC Concentration
4/1/2007 110010025 1 0.039
4/1/2007 110010041 1 0.042
4/1/2007 110010043 1 0.039
4/1/2007 240090011 1 0.042
4/1/2007 240170010 1 0.044
4/2/2007 110010025 1 0.051
4/2/2007 110010041 1 0.048
4/2/2007 110010043 1 0.052
4/2/2007 240090011 1 0.053
4/2/2007 240170010 1 0.055
4/2/2007 240210037 1 0.055