With a modest gain of more than 4% on the year, Enbridge's (NYSE: ENB) share price is faring far better than beleaguered midstream peer TransCanada. Stronger-than-expected opposition to its key project is creating quite a headwind for the company, however, and investors should take note.

Northern Gateway
At first there was just moderate opposition to Enbridge's proposed Northern Gateway project. The pipeline aims to connect Alberta's oil sands to British Columbia, where the oil would be exported via tanker. Opposition is coming from seemingly everywhere at this point. Environmentalists oppose oil sands development, First Nations communities and other citizens oppose the pipeline traveling over their land, folks in British Columbia are worried about increased tanker traffic in hazardous waters, and the list goes on.

In an attempt to overcome the ever-increasing opposition to its $5.5 billion project, Enbridge has launched a multimillion-dollar advertising campaign. The company's goal is to "help British Columbians understand what the project is about."

Enbridge has set up a website featuring information regarding economic benefits and environmental safeguards. The economic benefits of exporting oil are not difficult to comprehend, but people tend to be more cynical when it comes to energy companies protecting the environment.

Michigan spill
It might be easier to convince people that you are prepared for a pipeline leak if you had some sort of track record to back that claim up. Unfortunately for Enbridge, a recent report from the National Transportation Safety Board does just the opposite.

According to the report, when the Enbridge Line 6B pipeline ruptured on July 25, 2010, operators thought the ensuing shutdown was a false alarm and restarted pumping not once, but twice. Seventeen hours later someone realized that there was indeed a rupture in the line, a rupture that was more than 6 feet at its widest point.

Pipeline systems are complicated, and given the amount of infrastructure criss-crossing North America, the pipes really don't leak that frequently. However, if your employees aren't exercising extreme caution when monitoring pipelines, you cannot expect citizens to be OK with a pipeline in their backyards. For the record, the Michigan spill is still being cleaned up.

Foolish takeaway
It hasn't been all doom and gloom for Enbridge. The reversal of the Seaway pipeline it co-owns with Enterprise Products Partners (NYSE: EPD) is great news for the company, but there are too many things that could go wrong with this growth story for me to do anything other than add it to My Watchlist for now.