Near the place where it leaves the City of Guelph, in southern Ontario, the Speed River passes through a cedar forest that has a walking trail maintained by the Guelph Hiking Trail Club. 

The trail heads upstream along the western bank of the Speed, and gives people an opportunity to enjoy the river and the forest.

Close to the head of the trail, a sturdy foot bridge built by the hiking club crosses a slight low spot. The trail is not particularly challenging, and contains many low spots like this one – yet most don’t have bridges.

The builders left no clues to explain why they built a bridge here, but not over other low spots farther up the trail.

People who use the trail during dry, sunny days when it hasn't rained for a while may not realize that the bridge actually crosses a temporary stream bed.

In a dry summer, it takes an especially heavy rain to fill the upstream ponds in the forest that allow this ephermeral stream to flow. Storms like that may only happen a few times during summer.

When enough rain fills the forest ponds, this ephemeral stream will flow for a few days, pouring its water into the Speed River, which lies just below the bridge. After a few days of flow, once the ponds are empty, the stream bed dries up again.

This ephemeral stream is nameless. That's unsurprising given that most of the time, it's forest floor rather than a stream.

Walkers are much more likely to see and recognize a second kind of nameless stream they'll cross farther up the trail.

Intermittent streams flow longer, and more often, than ephemeral streams -- yet still not enough to warrant having a name.

Streams that have names are the permanent variety.

As their name suggests, permanent streams flow year-round, except during very dry periods. Unlike ephemeral and intermittent streams, permanent streams are often shown on maps.

The permanent stream featured here is Hanlon Creek. It joins the Speed River on the east bank, just upstream from the intermittent and ephemeral streams in these pictures.

Hanlon Creek takes its name from one of the original European settlers, Felix Hanlon, who owned land in this part of Guelph.

Nameless doesn't mean valueless.

Ephemeral and intermittent streams are an important part of the water cycle in southern Ontario. Like the tiniest blood vessels in the body, they are small but integral parts of much larger systems.

Streams like the ones shown here provide habitat for plants and animals, and supply water, sediments, nutrients and organic matter to downstream areas.

Protecting nameless streams is important to ensure they can provide these important functions.  To protect them, we first need to know they exist.

Water experts have the training to identify and distinguish ephemeral, intermittent and permanent streams. However, even people who are just out for a hike in the forest can learn to tell them apart. 

The main clues fall into three categories:

1. How much water flows in the stream, and how often.

2. The appearance of the banks and bottom of the stream.

3. The kind of vegetation that grows in the stream bed.

Experts deciding on the type of stream may also look under rocks for "aquatic invertebrates" such as sow bugs and stoneflies. These are common in permanent streams, occasionally found in intermittent streams, and never found in ephemeral streams.

Permanent streams flow for most of the year. During hot, dry conditions in July or August, their flows can be reduced to a trickle, or even stop. Hanlon Creek very rarely stops flowing.

Flows in permanent streams can be different along their length. Natural and artificial barriers can create ponds that slow them down. Steep slopes and narrow channels can cause them to pour downstream in a rush.

Unlike ephemeral and intermittent streams, the water table intersects the beds of many permanent streams in this region, meaning that their flows are a mix of groundwater and surface water. When groundwater provides a significant amount of the flow, the temperature of the stream water will be cold to the touch in hot summers.

Intermittent streams flow strongly in spring, when the snow is melting, and during summer and fall after heavy rains.They can flow for several weeks in spring, and for many days after large storms.

When fed with snow melt in spring, or very heavy rain falls in summer and fall,  parts of intermittent streams can have large flows that look like those of permanent streams.

Some intermittent streams, like the ones in these pictures, get part of their water from marshy upstream areas that act as sponges that hold rain water. This helps them flow a bit longer between summer rainfall events.

Ephemeral streams also depend on snow melt and rainfall for their flow. In spring, they can flow for days to weeks. In summer and fall, it takes a major rain storm to start these streams flowing.

Ephemeral streams like the ones in these pictures will only flow once shallow ponds in the forest fill with water. It took a storm that dropped approximately 50mm of rainfall in one day to fill the ponds and start the flow of the ephemeral streams shown here.

Streams rarely look the same over their entire lengths, so the character of the banks and bottoms can change from place-to-place.

Permanent streams will normally have prominent banks all along their lengths. Their banks can have steep, undercut sides, and sometimes a prominent lip. Or they can be gradual and sloping in areas where the water is moving slowly.

The bottom of a permanent stream is usually well-defined and looks quite different than the land through which it flows. Flowing water in a permanent stream scours the bottom. Sand, gravel and rocks are usually sorted (but this might be hard to see if there's a lot of mud or fine sediments).

In short sections, intermittent streams can have banks and bottoms similar to those of permanent streams. In those areas, the banks will be prominent, the bottom scoured, and sand, gravel and larger rocks in the stream bed sorted.

Intermittent streams typically also have large stretches where the banks and bottoms transition gradually to the surrounding forest floor. Scouring and sorted sediments may occur in these areas.

For the most part, ephemeral streams don't have well-defined banks and bottoms. In steep areas, where the flow of water is strong enough to carve a channel, a flow path with exposed soil and tree roots might be visible in the forest floor.

The beds of ephemeral streams in forests are formed of top soil, root mats and "duff" (a layer of partially decomposed leaves, needles and other plant matter).

When they are dry, It can be difficult to distinguish ephemeral stream beds from the adjacent forest floor.

In fast flowing sections of permanent streams, plants have trouble taking root in stream bottoms. Where the water slows down, plants are more common. These plants will always be the kind that grow in water rather than on land.

Land-based plants and trees will grow up to the very edges of permanent streams, sometimes clinging precariously to the banks. However, live tree roots will not be found in the beds of permanent streams.

Islands of forest vegetation sometimes form in the beds of permanent streams. The stream simply flows around them.

Plants that normally grow on land can be found in the beds of intermittent streams. This is a strong indicator that the stream dries up for a large part of the growing season.

Water-based plants can be found in intermittent stream beds if pools form that stay wet between rainfall events.

Trees growing near intermittent streams may send roots into their beds in sections where the flow of water is low and infrequent. Living tree roots in the stream bed are a good indicator that the stream is intermittent.

Except where high flows have carved a flow channel in the forest floor, ephemeral stream beds match the surrounding landscape.

Trees and other land-based plants will happily grow in their beds. The layer of duff that covers the rest of the forest floor will be found in the stream bed.

Another bridge crosses a stream on the hiking trail -- this time one of the intermittent streams that intersects the hiking trail on the west side of the Speed River. This stream doesn't have a name, and unlike Hanlon Creek, which joints the Speed almost directly across the river from this spot, it doesn't appear on maps.

Nonetheless, this nameless intermittent stream plays a small but important role in the forest environment. It helps to keep the Speed River flowing, provides habitat for plants and animals, and adds to the enjoyment people experience as they walk along this trail.

It deserves our care and protection.