On "AC360" tonight, five survivors of the BP oil rig explosion tell Anderson Cooper how they got out alive. Watch "AC360" tonight, live from the Gulf at 10 p.m. ET.
(CNN) -- Sam Waterston says he was wrong.
The actor, who serves on the board of an international ocean conservation organization and opposes offshore drilling, nonetheless thought the risks were low.
"While I thought it was terribly important to stop ocean drilling, I was partly -- and I'm ashamed to say this -- I was partly persuaded by the last 15 or 20 years that it could be done safely and without grave environmental damage," he told CNN in a phone interview.
And now? With the oil disaster in the Gulf continuing unabated, "I think this is an enormous wake-up call for all of us, that we never, ever buy that argument again."
Waterston, 69, who traces his interest in marine issues back to his New England childhood, is hoping the public channels frustration with the oil fiasco into action. The actor, who concluded 16 years as District Attorney Jack McCoy on "Law & Order" with the show's final episode last month, will take part in a July 10 "awareness-raising" charitable event for Oceana, the group founded by actor Ted Danson. Waterston says he hopes that interest stays high even after the oil well is capped and the cleanup takes over.
Waterston spoke to CNN about the oil disaster as a "turning point," anger at celebrities and -- yes -- a little "Law & Order." The following is an edited version of the interview.
CNN: What can be done? It's a very frustrating time for everybody.
Sam Waterston: I hear it from people all over the place. They're feeling helpless and don't know how to respond. [With Oceana,] they can weigh in on this with a lot of other voices, and therefore be more likely to have their voices heard in talking to their representatives and the administration.
This should be a turning point in all of our minds about what our course ought to be about energy supply in this country if we want to preserve the oceans as we know them. ... There's no way to escape the fact that these carbon-based fuels are poisoning the ocean upon which we all depend.
CNN: How do you respond to folks who say environmentalism is all well and good, but the oil industry brings in a lot of money -- and we need it for energy?
Waterston: I think one of things that this disaster shows is -- for the jobs and the energy it produces -- when it is misused, or misproduced, it causes terrible economic damage, and terrible damage to people's lives, not to mention what it does to the environment.
CNN: I wrote an article about celebrity involvement recently, and some people responded angrily, accusing celebrities of being dilettantes. How do you respond to that anger?
Waterston: Well, I don't know what to say to that, except that as a citizen it's a privilege to be able to have the power to point at things. If a few people are going to take shots at us for that, I think it's probably well worth it.
CNN: A "Law and Order" question: What feelings are you left with, now that it's been canceled?
Waterston: It just doesn't happen -- shows don't go this long. I had a wonderful ride, and I have absolutely nothing to complain about. I keep hearing rumors that it's going to revive itself in some other form, so I don't even know that it's actually finally, finally over with. I'm sorry that [creator] Dick [Wolf] didn't get to break the record, but I think tying the [drama series longevity] record [with "Gunsmoke"] is pretty good, and I'm completely happy with my lot.