Unfortunately, stormwater brings a lot of risks. The land area represented by human structures is growing, which means the surfaces available on which the earth can manage stormwater using natural means are shrinking.
This is causing serious trouble in our cities. And, since basically everywhere is downstream of somewhere else, the problems then travel to the country, to wilderness areas, to wetlands and waterways, and eventually to the ocean.
An increase in stormwater runoff can exacerbate existing, or introduce new, pollution problems. This is particularly true in urban areas, where “More frequent and intense downpours, projected for all regions of the country, can overwhelm the design capacity of municipal stormwater management systems. Overwhelmed stormwater management systems can lead to backups that cause localized flooding or lead to greater runoff of contaminants such as trash, nutrients, sediment or bacteria into local waterways.”
In other words, if you’d like to keep the contents of someone else’s toilet out of your drinking water, stormwater management is the key.
It’s not just an issue in urban areas, however. Rural property owners also face trouble from stormwater that arrives at their property in the form of flooded waterways from rain or snowmelt. They may also lack the ability to manage it when it falls from above, overflowing existing streams and ponds and creating large floodplains. This can endanger homes, garages, and outbuildings.
Similarly, farmers face dangers from flooding. Unmanaged stormwater can drown crops, carry pollutants into fields, and overflow clean waterways with dirty water. This is especially dangerous for organic farmers, who need to maintain high standards of purity in order to keep their certifications. It’s risky overall, however, since excess water of any kind can damage crops and endanger profits.
Where Does It Go?
So, when stormwater isn’t flooding a farmer’s fields, where does it go?
Good question, with a few different answers. In cities, stormwater tends to travel further because of the increased amount of impermeable surfaces. However, the countryside does have its share of hard surfaces in the forms of industrial areas, utilities, agricultural operations, airports, and more. Overall, stormwater falls into some variation of the following categories.
Runoff
“Runoff” is any type of stormwater that is moving over a surface. That can include streets, parking lots, rooftops, and even lawns. Since unaerated lawns with a lot of thatch built up are significantly impermeable, water often simply runs right off. That’s why it’s important for homeowners who want to keep their lawns to maintain a healthy environment beneath the surface grass, which we will discuss below.
Due to the wealth of impermeable surfaces in cities, runoff is a primary issue here. Oftentimes, stormwater has nowhere to go for several streets or blocks. Sewers and storm drains do help to redirect water into passageways below the city, but in extreme weather events, these aren’t enough. They may back up and overflow into the streets, adding effluence to the runoff that then gets carried elsewhere.
While runoff is a major problem inside cities, rural communities are not exempt. Any time water flows from a hard surface and collects, that is runoff. In the countryside, explains the Copper River Watershed Project, “Runoff from roofs, driveways, sheds, and other impervious surfaces flows to the storm drain and road ditches that flow directly into our anadromous streams and lakes.”
Luckily, harvesting stormwater can help prevent runoff anywhere, from the most remote compound to the biggest city.
Parks and Greenways
When stormwater falls on or flows into parks and greenways, it is often absorbed. That’s why green spaces dramatically decrease the amount of runoff we have to deal with. Mulch, soil, plants, and trees all provide excellent stormwater management, pulling it down into the ground where it either filters through to the aquifer or nourishes plants.
Yards and Gardens
Like parks and greenways, yards present excellent stormwater management potential. Home and business owners that add stormwater harvesting systems such as cisterns and barrels to their roofs and side yards can do even more for their world. With the price of water these days, getting it for free isn’t a bad idea either!
Retention and Detention Basins
These are huge stormwater management strategies, relying on large depressions in the ground to collect rainwater and snowmelt and either hold onto it or funnel it along later, after peak runoff times. And by “huge,” we mean physically huge, so they’re not the right answer for everyone. However, they are an excellent way to collect runoff in places like office or apartment complexes, the outskirts of cities, and near shopping malls and hospitals.
We will discuss both retention and detention basins, or ponds, in much greater depth below.
Waterways
Of course, some stormwater simply falls into bodies of water. These include lakes, rivers, streams, deltas, the ocean, and so forth. This is ideal, because then stormwater lacks the chance to pick up toxins, pathogens, and other ick on its way to our waterways.
Speaking of ick, let’s take a quick look at the risks of runoff.
The Risks of Runoff
Impervious surfaces are highly problematic in urban areas, because they don’t allow water to soak down through the soil and go back into the aquifer, as stormwater does in wild areas. Instead, the stormwater runs off of those surfaces – streets, parking lots, driveways, school grounds, etc. – and gathers in gutters, low patches, or boggy greenways.
While the number of impermeable surfaces is on average lower in rural areas, these problems still occur there as well. This has a number of downsides, including:
- Pollution: Our hard surfaces are covered in pollutants. Toxins from household products, seepage from cars, flaking paint, and other inorganic compounds can all pose a risk to the health of people, animals, vegetation, and ecosystems. Water also strips smog out of the air and picks it up off of surfaces, which increases its polluting potential.
- Disease: As discussed above, extreme weather can cause sewer overflows, which send sewage back up into the streets. Since human waste carries significant disease potential, this increases the danger of waterborne sickness quite a lot. (Think of a river in a developing country, where everyone washes their clothes and gets cooking water from the same river that upstream users put their waste in.) Harvesting stormwater does much to reduce this risk.
- Erosion: Stormwater carries away topsoil, mulch, and even gravel in its wake. While erosion is a natural process to a certain extent, stormwater often means that it happens too quickly. We lose the soil out from under a tree’s roots, for instance, killing the tree. Or water erodes the clay on which a home sits, leading to …
- Property loss: When stream channels widen, that can lead to the loss of valuable public or private property. Stormwater runoff, especially at peak times, can pack a punch. That leads to eroded streams and riverbanks, boggy land around developments and homes, and instability of foundations. Any of these outcomes can endanger a home or business – or many at once.
- Ecosystem disruption: Pollutants and pathogens disrupt wildlife ecosystems as well. We humans, after all, aren’t the only ones at risk of catching disease or getting cancer. This happens to animals in the wild as well. Plants, similarly, can be compromised by contaminants in the water. And when one part of the ecosystem is affected, others can be as well. Food webs get damaged or disrupted this way, sometimes changing them entirely.
- Eutrophication: This is a fancy way of saying “overgrowth of green, algae-like things.” Eutrophication is the process by which algae and their cousins receive an abundance of nutrients through runoff (think fertilizers and other chemicals), which causes them to grow rapidly. They then use up all the oxygen in the water, gunking it up and killing other plants or animals trying to live there. It’s ugly, smelly, and bad for ecology overall.
- Closure of public facilities: When runoff contains diseases or hazardous chemicals, this affects the surrounding waterways that people use. For instance, heavy runoff can often lead to beach closures, because swimming becomes dangerous due to the presence of pathogens and carcinogens.
- Contaminated drinking water: Lastly, contamination of drinking water is a serious issue. While developed countries have a better handle on this, developing ones often see outbreaks of waterborne diseases such as cholera. However, even in the U.S., “sometimes unsafe levels of harmful germs and chemicals contaminate public drinking water. The germs and chemicals can get in the water at its source (for example, ground water or water from lakes or rivers) or while water is traveling through the distribution system, after the water treatment plant has already removed germs and chemicals from source water.”
Overall, runoff is best avoided, which is where stormwater harvesting and management come in. That said, stormwater isn’t all bad.
Stormwater: Not a Net Negative
It’s important to note that stormwater isn’t necessarily bad. In fact, it’s a critical piece of the water cycle. When rain and snow precipitate out of clouds and land on the ground, they are redirected back to aquifers and waterways, where they replenish our water tables and maintain ecological balance.
The problem is when cities or other human establishments “get in the way.” That can be bad for the environment, which gets disrupted by erosion, disease, and pollution. And it can be bad for humans, for whom these outcomes are also detrimental.
The good news is, if we can reduce the amount of runoff in cities and rural areas through the use of smart stormwater management strategies such as retention and detention ponds, we can significantly reduce these issues. Not only that, we can increase water access for areas that have too little of it.
We’re getting a little ahead of ourselves, though. First, let’s take a look at just why we need stormwater harvesting in the first place.
