X0304 4 2012-02-21 0000742126 US ECOLOGY, INC. ECOL 0001272447 COOPER JOHN M 300 E. MALLARD DR., SUITE 300 BOISE ID 83706 1 VP and Chief Information Off. Common Stock 2012-02-21 4 A 0 1300 0 A 9300 D Common Stock Option 19.71 2012-02-21 4 A 0 6200 0 A 2012-03-21 2022-02-21 Common Stock 6200 6200 D Common Stock Option 21.74 2007-07-27 2016-07-27 Common Stock 10203 10203 D Common Stock Option 23.48 2008-12-06 2017-12-06 Common Stock 4000 4000 D Common Stock Option 20.63 2010-01-02 2019-01-02 Common Stock 10000 10000 D Common Stock Option 15.36 2010-04-08 2020-03-08 Common Stock 6300 6300 D Common Stock Option 16.18 2011-04-10 2021-03-10 Common Stock 6200 6200 D Issued pursuant to 2006 Restricted Stock Plan, vesting monthly over 12 month period. Issued pursuant to 2008 Stock Option Incentive Plan, vesting monthly over 3 year period. /s/ John M. Cooper 2012-02-23