Sunday was the fourth anniversary of the explosion aboard the BP/Deepwater Horizon oil rig. The passage of time might be fading the memory, but it shouldn’t be forgotten.

The rig sank and, two days later, 5,000 feet below the surface, oil began pouring into the Gulf of Mexico from the blown-out wellhead. It continued for 87 days, making it by far the worst environmental disaster in our nation’s history.

To put it in some perspective, the infamous Exxon Valdez disaster dumped 11 million gallons of oil, a drip compared to the estimated 206 million gallons the BP/Horizon spewed out. It impacted five Gulf States, thousands of businesses, including boat dealers, marinas, charterboats and many more. And the effects continue to roll in.

For example, in March hundreds of tar balls washed ashore on Florida’s panhandle beaches. Reportedly, some 37,000 tar balls were picked off those beaches last year. Similarly, globs of oil continue to wash up on Louisiana, Mississippi and Alabama beaches.

Fish are being impacted in a variety of ways and the long-term future is unknown. For example, scientific research has identified a huge die-off among tiny creatures that form the basis for the food chain. Gulf corals have died. Anglers have been catching fish with tattered fins and lesions. Dolphins in southeastern Louisiana’s Barrataria Bay are suffering from severe health problems. The mangroves on Cat Island that once were nesting grounds are all dead. And on it goes.

According to government scientists, severe defects in the developing hearts of Gulf bluefin and yellowfin tunas and amberjack have also recently been identified. It has been labeled “a significant cardiac injury” by Stanford University professor of biology Barbara Block, one of the authors of the study. The heart defects likely mean an early death.

Truth is, it will be years before we really know how the spill affects our health, seafood supply, recreation and the businesses whose livelihood is Gulf dependent. The spill and bloom covered more than 360 square miles of Gulf waters. Up until now, BP has paid more than $13 billion in business and individual claims. It has reached a medical settlement that could provide up to 200,000 people with health care services for decades ahead. That’s as it should be and makes BP look like it’s doing the right thing.

But not so fast.

BP is now vigorously contesting payouts under a court-approved civic settlement BP agreed to and signed. On another front, BP is challenging the federal claim that it spilled 206 million gallons of oil into the Gulf. Lowering the gallons could reduce its Clean Water Act fines by billions. BP is embroiled in a lengthy trial in federal court in New Orleans that could eventually yield billions of dollars in damages.

Last month, BP agreed to new safety and operating rules that got a ban from new contracts with the U.S. government lifted by the EPA. That puts BP back in the game for drilling leases in deep water. In fact, since the BP disaster, regulators have approved nearly all of hundreds of exploratory plans in the Gulf. Right now, the drilling areas contain 6,000 leases covering 31 million acres and a new drilling plan calls for opening up some 94 million acres more by 2017.

There’s nothing wrong with new drilling. We need to drill in deeper water for oil, but we must do it better. Change is needed or we still have a recipe for trouble.

Investigations have led to proposed new regulatory and industry standards for well designs and emergency responses. Sadly, none of the most important standards have been written into law. Those need to be firmed up.

Moreover, the Obama Administration has proposed doubling the $75 million cap on oil-spill liability, the first increase in fines in 24 years. Nice, but hardly a deterrent to the possibilities of risky, corner-cutting drilling operations as was found with the BP/Horizon operation. After all, BP’s 2013 profits were $13.4 billion — a $75 or $150 million cap on liability will be just a cost of doing business.

The BP disaster isn’t over. More research is needed to determine the long-term impact. It’s important to keep the needs in focus.