The first rule of draining - exploring and photographing storm sewers and drains - is to stay out if it is, or will be, raining. Like most "rules" in the anarchic subculture of Urban Exploration, it's more of a fast-and-loose guideline, one that's considered stupid, obvious, and common sense, and many of the maverick teenagers on the fringe of UE doubtless ignore it, as they do most of the other tenets and guidelines of this hobby and, indeed, day-to-day life.
They do so at their peril.
A typical storm drain is a relatively safe environment to explore. Arrest, electrocution, serious injury, wild-animal attacks, encounters with transients; all are of greatly reduced likelihood in a drain. Keeping your footing in the inch or two of water typical of most drains isn't terribly difficult, and slipping is, for some people, half the fun. Compared to steam or utility tunnels, or abandoned buildings, storm sewers are safe.
When it rains, all bets are off. Water is the enemy. Rain kills.
Three of us entered a large storm drain one summer night at about 1930. It was hot, and humid, and cloudy. Rain was forecast, but the odds were low, and it was predicted to be several hours off. We paid it no great heed. Carrying cameras and tripods, we walked downstream through a few inches of cold, clear water, passing a gaunt and water-logged hedgehog near the entrance who seemed curiously unbothered by our presence. Given the temperature outside, the drain fog was especially bad, and we searched in vain for a picturesque section of tunnel with the least amount of fog possible. Along the way, we realized that we'd forgotten to bring the rope ladder - necessary for an easy, safe, and graceful egress, but there was nothing we could do. After about a mile, it was decided the fog just wasn't going to get any better than it was, so we turned to retrace our steps about halfway, to a foggy but beautiful section of tunnel we'd identified before.
We noticed, at first, that the fog seemed to be growing worse as we retraced our steps. Far worse, in fact, and the air smelled faintly of gasoline. We were willing to dismiss this with any number of plausible explanations, when one of us pointed out the large volume of debris floating past us in the now-murky water around our ankles. Leaves and grass. Cigarette butts. Styrofoam cups and plates. Empty soda bottles. Shit, we all said, it must be raining. We headed upstream as fast as possible, knowing we had the better part of a mile to go, against the current.
It wasn't just the current; the water level was rising. Already it had nearly doubled, a fast-moving body of water with an increasingly powerful current. As we trudged upstream, more, and larger debris came racing past us. A four-foot length of six-inch tree branch was swept past. More pop bottles came streaking out of the fog and raced between our legs. Small chunks of broken, waterlogged plywood arrived and departed against a background white noise of rushing water.
The corners were the worst, as the current tore at our legs at a diagonal, the water still rising. Some ten inches of fast-moving stormwater, too deep and too strong to let us lift our legs out of the water with each step, so that we were forced to trudge against the flow with each step. Several times we were almost upended as we slipped or stumbled on uneven sections of the floor, or heavy debris under our boots. Moving against the water was a chore, the tunnel seeming endless, and grabbing on - tieing on - to a pipe or stepiron and waiting it out began to grow in it's attractions.
We fought on towards our egress point - the only one for miles in that drain - and finally came to the final stretch of tunnel, the two less-athletic of us unsure if we'd even be able to get out at all without the ladder. Though this part of the tunnel was broader, the water here was still close to a foot deep at the edges, perhaps eighteen inches in the middle, and the current, while reduced, was still very dangerous. Looking up the manhole shaft, we saw sunlight shine invitingly of warmth and safety. It had stopped raining, but the drain was still rising.
I'm an idiot, with a soft place in my heart for animals, and an all-too-keen awareness of karma. Seeing the poor hedgehog struggling against the waterflow to keep it's head above water, despite the still very real danger to me, I just had to try and rescue it. With some inarticulate shouts to my companions that couldn't be heard above the rushing water, I cautiously - very cautiously - approached the poor little thing, and tentatively placed a hand on it's back. It made no move to bite me or claw me to death, so after a few abortive attempts, I managed to life him (very emphatically a he, once his rear end was out of the water) in one hand and trudge cautiously towards the entrance. Just a little fella, about six pounds fully soaked with water, he seemed to be scared witless - I could feel his little hedgehog heart pounding in my hand - but he seemed to understand that whatever I had in mind was probably better than struggling against the stormwater. It took some effort, but I got him up by a slit in the side of the tunnel, a grated infall sort of thing, and he leaped for freedom without a moment's hesitation. Score one for the good guys, I guess.
The small mammal now out of our concern, we large mammals made our none-too-soon ascents in a graceless and awkward spectacle best left undescribed. Back on the surface, the manhole lid kicked back in place, we stood and sat, soaked and panting, and we all agreed, that, indeed, that sucked.
We were drenched, soaked to the waist and above, our boots flooded, our bags and packs damp from spray and splashes. As we trudged back to the cars, dripping, the adrenaline of the last forty-five minutes began to wear off, and we began to realize, and talk about, the gravity of what we'd just experienced. It was an eye-opener to the very real hazards of drains, the suddenness with which conditions can change, and a much-needed reminder both of our mortality, and how accustomed and blase one can become about living on the edge.
It had rained for less than forty-five minutes, with only twenty minutes of anything approaching serious rain, the remainder of that period being little more than sprinkles. Not even a thunderstorm, or serious, hard rainfall, just brief, steady light rain. The official rainfall for that day was 0.05 inches. Five-hundredths of an inch of rainfall in more than half an hour, and the level of water rose a foot. We'd had no warning of the rain, and deep underground, it's unlikely we'd have heard thunder had the storm been more severe. The suddenness of the changes, the severity of the changes, the unbelievable power of five-hundredths of an inch of rain is mind boggling, and I really hope our near-disaster can serve as a graphic example of why rain and draining don't mix. Kids! Don't try that at home!