Channeling Your Inner Pond
This is an Eartchache, which means there is NO container to find. Instead, its a visit to a geographic location with the intent of learning about the geology. Thus, read the information about how ponds can be part of a braided river channel, make some observations in response to 4 key questions, and then send your answers to the cache owner. At that time you can log your find.
This is about seeing some ponds as more than ‘just a pond’, but as part of a dynamic river system. In our case, these ponds are a part of the Willamette River system. You are standing at the Delta Ponds, a City of Eugene Parks & Recreation nature trail. But what you are looking at is more than just a pond.
A pond is less than a lake, but more than a puddle. While we might enjoy a stomp in a puddle, stomping in a pond is pretty messy. The Delta Ponds hike is roughly 1.5 miles of meandering pathways with amble benches for relaxation and signboards filled with information. Through this Earthcache, you will see how these ponds are part of an important river system.
Most people will say a pond is just a very small lake, often shallow and not where one wants to swim. Not all ponds are alike and where you are standing today is a type of pond that breathes life back into the river and saves the local area from flooding. We might now now from just glancing. It takes some keen observation to notice what makes these ponds special. .
As you stop at the series of stops along the walking path, read about the descriptions of ponds and river side channels, and look for evidence of both. Are you at just a pond or on part of the river?
You are standing next to a side channel of the Willamette River, with some ponds built into it. Since the water flows from the Willamette River, past these man made islands, and back to the lower section of the Willamette River, this is part of a braided river channel. Your job today is to find evidence of how this area can be both a braided RIVER channel and a POND, at the same time.
What makes a pond a pond?.
A pond is a small, still, land-based body of water formed by pooling inside a depression, either naturally or artificially. Ponds were part of the landscape before the gravel pit was created. In the 1950s, this area became an active gravel mining site, and when mining efforts came to a stop, the area was abandoned and in poor ecological health (deep holes in the ground, no water flow, contaminated soil, no connection to the river). The City of Eugene purchased the ponds in 1979 and, later, in 2004 began a major restoration project. What you see in front of you is still ‘in process’ as invasive plants are weeded out to give native flora the best chance possible. There is still work being done to create a channel flow of water throughout the ponds.
A pond is smaller than a lake and there are no official criteria distinguishing the two, although defining a pond to be less than 12 acres in area, less than 16 ft in depth and with less than 30% of its area covered by plant life. Ponds, such as these, can vary in depth and current, depending on winter and spring flooding from the Willamette River.
As you look across these ponds, look for evidence of this area being a pond. Notice that the pathway is not much higher than the pond itself. Notice the distance across the pond, it isn’t very far to the other side. The ponds are very shallow, something that is more noticeable in the summer and autumn months when the river is running low. As you walk around the Delta Ponds, notice that elevated walkways are needed to keep walkers away from the mud, flora, and fauna. If you walk here in the evening, you might be lucky enough to see one of the beavers collecting wood.
So, what is a braided RIVER channel?
A river is a large natural stream flowing in a channel to the sea, a lake, or another such stream, the Willamette River is a large river that travels northward along the Willamette Valley to the Columbia River, from there to the Pacific Ocean. A healthy river is much more than ‘just a river’, it will meander and create side channels, some that look like braids if you see them from above. In Spring, when the rivers tend to run faster and higher, the water spreads into low-lying areas. Where you stand now was once part of a side channel, that later rejoined the Willamette River. An ‘overflow’ channel created by the power of water.
If you time-traveled back to over 200 years ago, this area looks quite different. Yes, there would be no modern buildings, roadways, or cars, but you would see evidence of a braided river channel.
A braided river (also called braided channel or braided stream) consists of a network of river channels separated by small, often temporary, islands called braid bars. A sandbar, dirt bar, or small first island is common. Look out at the islands within the ponds and admire the many small islands. Look at the shape of the islands. If there is a current, the current would erode (wash away) some of the island/bar materials.
These narrow islands also offer safe habitat for many plants and animals. Safe from what? These islands offer safe nesting grounds where the animals don’t have to worry about dogs, cats, and other terrestrial animals. But I digress, let’s look back at the idea of this also being a channel.
Braided streams tend to occur in rivers with high sediment loads. Look around, do you see mud, silt, and/or gravel? It will depend on how high the water is during your visit, but would you really want to walk out to the center of these braided channels or would you sink in the pond mud? If those islands were not’ there, and it was just ponds alone, this would not be a ‘braided channel’.
How many islands/bars do you see in these channels/ponds? If you are visiting when the water is low, you will see many low, muddy sand bars where a human would get stuck knee-deep in mire. These islands/bars are often unstable and temporary. They will change in size and shape, depending on the flow rate from the Willamette. Birds can land on these islands/bars and find food to eat, but larger animals would struggle. During higher water flow, you can see the current flowing through, but the lower sand bars/braids/islands are under a few inches of water. The man-made islands/bars still are visible, even if the water current is so mild that it is hard to see.
On the more permanent, man-made islands, look for vegetation. This helps make the islands/bars more stable in a braided channel. The vegetation helps prevent erosion. The City of Eugene does routine care where they weed out the invasive plants in order to allow for native plants to thrive.
As you walk around the Delta Ponds, look for evidence of how humans keep the water flowing through the ponds. There is an extensive set of weirs/dikes that are used to increase or decrease the flow of water from the Willamette River. These weirs require a person to come and turn wheels to open and close gates that allow for water movement. It’s a solution that has helped the Delta Ponds become a destination for nature lovers and bird watchers alike. As you cross over the bridges, walk on the raised walkways, notice the water level and contemplate how the same area will look under different conditions (at low water vs. high water).
While the Willamette River has been heavily shaped, and limited, as people built cities and industry, there are areas similar to the Delta Ponds. Communities are working to reestablish a healthier river system.
To document your findings, please send your answers to the cache owner (do NOT post to your log) :
- What evidence of a braided river channel do you see? Look at the description of braided channels and find at least one example that would exist in a braided channel (as opposed to any river or a basic pond). Hint: Look at how many islands and the shape of the island.
- What evidence of a POND do you see? Look carefully for evidence of a depression, or slightly lower elevation compared to the walking path and/or roadways.
- How high is the water compared to what is likely the high winter flow? How can you tell that the water is low, normal or high? Think about winter and spring flooding and how this pond area shows evidence of low and high water.
- Are you at a pond, a braided channel or both? You decide and back it up with your reason.
- Post a picture of yourself, or of wildlife, at the ponds. Use this picture as a part of your log
Resources
Braided Rivers Wikipedia
https://en.wikipedia.org/wiki/Braided_river
Accessed 4/20/2025
Eugene Delta Ponds
ttps://www.eugene-or.gov/DocumentCenter/View/31092/Delta-Ponds-Brochure-and-Map?bidId=
https://www.eugene-or.gov/facilities/facility/details/Delta-Ponds-133
Ponds- Wikipedia
https://en.wikipedia.org/wiki/Pond
Accessed on 4/20/2025
NOAA “What is a Wetland”
https://oceanservice.noaa.gov/facts/wetland.html#:~:text=Common%20names%20for%20wetlands%20include,to%20name%20just%20a%20few!
Accessed 4/19/2025