Monitoring Doan Creek
The Park Service has been recording stream data since water began to flow through the new Doan Creek channel. On a weekly basis, at five different sites along the creek, the Mission collects the following measurements:
Dissolved Oxygen (DO): This is a measurement of how much gaseous oxygen is in the water. Oxygen is put into the water by vegetation as a product of photosynthesis, and it is important for aquatic animals, like fish, whose cells need oxygen just like humans.
Temperature: Water temperature is a significant factor, especially for fish species sensitive to temperature fluctuations. Salmon species prefer a temperature range of 54˚F-57˚F, and anything higher than 77˚F can be deadly. Temperature and DO are related, because the warmer the water, the less dissolved oxygen the water can hold.
Turbidity: This is a measurement of clarity, or how much sediment or other particulate matter the water contains. Turbidity is measured by placing a sample of the water in a vial and then putting the vial in a machine that shines a light through the water. If the light passes through easily, the water has a low turbidity, and vice versa. High turbidity levels can have a negative impact on fish vitality.
Flow rate: This is a measurement of how fast the water is moving through the channel.
Stream dimensions: The width and depth of the channel at any given location is used in conjunction with the flow rate to calculate the cubic feet of water per second moving through the stream channel. This is a standard measurement of discharge for a river or stream.
pH: This is a measurement of acidity or alkalinity of stream water. A pH of “7” is considered to be neutral; anything lower than 7 is acidic, and anything greater than 7 is basic. It is important that pH be within a certain range to support aquatic life. For most fish species a pH range of 6.5-8.5 is considered acceptable.
The Park Service had the unique opportunity to collect stream data from the very beginning of the restored creek's existence. Recording data regularly is analogous to administering regular “checkups” on stream health, and taking its vital signs. The main goal is to maintain a creek that is optimal for fish passage. The Mission uses the water standards set by the Washington Department of Ecology as a guideline for ideal fish habitat. Consistent recording of data allows the Park Service to determine whether it needs to make changes to the creek dynamics to produce a healthier stream for fish.
Written by Kari Martin, Spring 2007 Whitman College water-monitoring intern.