Systems using surface water, rather than ground water, are required to take extra steps to protect against bacterial contamination because surface water sources are more vulnerable to such contamination. At a minimum, all systems using surface waters must disinfect. Disinfection will kill E. coli O157:H7. [source]So should Portland blame its reservoirs or the lack of sufficient treatment?
Contractors are in place to disconnect our hundred year old system, not because it's broken, but because the EPA says we have to.
Do underground, versus surface sources, also contain E. Coli sometimes? Yes.
Given E. Coli has nothing to do with why the EPA wants this system shut down, we at least have a litmus test: any politician using the E. Coli scare to make points for closing is willfully clueless and a self identified lackey for the contractors / businesses standing to gain financially from the EPA's one-size-fits all ruling.