Stream Restoration Project
- Dedication
- Background
- Project Objectives
- Project Description
- Photos
- Understanding the Current Water Level
Background
Degradation of Hyde Lake and its wetlands began in the 1960's when the wetlands and marsh at the south end of the lake were drained for agricultural purposes. The once small creek was dredged and straightened, leading to erosion that widened the creek, drained the wetlands, and lowered the lake level as much as four feet.
The Save Hyde Lake Association and two private land-owners have partnered with the US Fish and Wildlife Service through its Partners for Fish and Wildlife Program to complete a stream restoration project on the outlet of Hyde Lake. The Service has designed and implemented the project. The Service and the Save Hyde Lake Association have funded the project.
Project Objectives
- To restore the headwaters of Hyde Creek to a natural channel and to stabilize water level at Hyde Lake using fluvial geomorphology design techniques.
- To enhance the adjacent riparian wetlands through the restoration of the Hyde Lake outlet.
- To inmprove habitat diversity to benefit aquatic and terrestrial species.
Project Description
Click on photos to see larger images
The US Fish and Wildlife Service designed the water control project and began construction in February, 2005. The project was designed using the concept of geomorphology which involves determining the historical flow of a stream and installing a highly engineered system that will restore the stream to its former natural state. The weir (dam) is based on the work of Robert Newbury, Vancouver, Washington.
The first stage 
was to establish grade control by installing 90 feet of vinyl sheet piling 12 feet deep into the ground. An eight foot spillway was notched in the central portion of the sheet piling to allow for stream overflow. A rock base was established on the down-stream side using 240 tons of fist-sized rocks to form a gentle grade to the stream channel.
The second stage was to install
a rock cross vane downstream to account for the grade change from the lake outlet to the culvert on Hyde Lake Road. Huge slabs of limestone were placed in such a way that the water folds over the rocks as it flows downstream, minimizing the energy and velocity of the stream.
"In a couple years it is supposed to look like we've never been here," said Carl Schwartz of the US Fish and Wildlife Service.
Before
After
Before
After
Understanding the Current Water Level
When we look at the current water level of the lake, it is obvious that it is at a lower level than most of us had anticipated. There are several reasons for this outcome that I hope will clarify any questions you might have. Keep in mind that the water level is stabilized at a minimum level and should not drop any lower.
First of all, the water level is not lower due to any problems or malfunctions of the new stream system. The new system is functioning very well. However, the weir, or the dam-like structure, was constructed at a level that is approximately 1 foot lower than the top of the old "beaver dam", which provided the higher water level that we have had in the past.
Why was the weir constructed at a lower level?
Sound engineering practices required the structure to be anchored to strong, stable stream banks that would be most resistant to erosion coming from the force of the flow of water out of the lake. This location was selected because it is the section closest to the old "beaver dam" that is stable enough to support the construction. It was the highest elevation possible.
What does this difference in height mean?
It means that our water level will most likely fluctuate within that 1 foot range depending on beaver activity and the amount of rainfall that we receive.
What is the other reason that the water level is lower?
Think of the lake as a bowl with a warped rim; the highest spot on the rim is where the top of the old beaver dam is. Since water seeks the path of least resistance, when the bowl is filled with water it will flow around the sides of the high spot. This is what has been happening to the old dam. Because the only material on the sides of the dam is loose and unstable bog, it has eroded. Also, keep in mind that the old dam is just that, "old"- over 30 years old, and much of the original material has deteriorated.This winter the beaver dam failed terribly; in February, water was flowing through on the Wilson side. We suspect that the leak is down below the current surface level of the water. This allowed the water to drain out until it was contained by the newly constructed weir. Just think, the way the old beaver dam was and is failing right now, without the new weir, we would be looking at a water level that would be 2-3 feet lower than it is currently.
If the beaver decide to make repairs to the leak and maintain it then the water level will go up. Also, if and when it rains, the water level should rise again and then run out at a slower rate because we have attempted to block the leak in that area.
In time, soil and debris will deposit itself in the stream and it will fill in where erosion has occurred, hence, stream restoration. Until then, I hope everyone keeps in mind the deteriorating condition of the old beaver dam and is appreciative that the new structure is in place to ensure that the water level does not go any lower.