As David said, it's definitely a job for the Neighborhood Law Corps. They have been making successful cases against illegal dumpers. Do contact them. Here's the info about who they are and what they do that David mentioned:

http://www.oaklandcityattorney.org/community/nlc.html

That's District 3. Lynette McElhaney is the councilmember. She has, herself, made illegal dumping reports. Lmcelhaney@oaklandnet.com

Her policy analyst, Casey Farmer always replies to emails. I always cc her on anything.

Casey Farmer, Policy Analyst
Email: CFarmer@oaklandnet.com
Phone: (510) 238-7031