We would like your feedback
We are looking for feedback on our draft total maximum daily load (TMDL) report which describes water quality issues with the Nooksack River and potential methods to fix them. We will be accepting comments from Sept. 12 until Nov. 20, 2018.
After the comment period closes, we will consider comments received and respond. The final responses will be posted here. Then, we will send the final document to EPA for approval.
Water quality issues
Logging of large trees in the upper watershed changed the original river channel. Logging exposes soil and removes vegetation with deep roots. This makes it easier for soil to creep. This erodes the river banks and makes the river wider and shallower. The river is also relatively shallow, which makes the water much warmer. South Fork is a popular recreation area because the water is so warm. However, warm water is not good for fish. Also, there is no glacier to feed the river so there is not much cool inflow.
We do know there was a time when the river was crowded with fish. We want to restore the river as much as we can to give fish a chance to survive. We believe the South Fork was cooler and more habitable when it was teeming with fish, even though it may not have met state temperature criteria.
What has been done
In 2011, EPA hired a contractor to put together a shade and temperature model of the South Fork Nooksack River using existing data. Models are used in TMDLs often to simulate existing conditions and run scenarios to understand the system and to determine what needs to be done to improve water quality — in this case, what needs to be done to reduce stream temperatures. The model simulates water temperatures along the length of the river based on measured streamflow, air temperature, humidity, wind, and shade using known physical processes. Changing available shade and air temperatures allows us to evaluate different conditions. The results were published in the TMDL study.
A few key results of the study include:
The Tribes would also like Ecology to address excess fine sediment entering the entire Nooksack River. The TMDL study did not assess what it would take to reduce the fine sediment in the South Fork, but the riparian fixes to include shade trees along river corridor will help reduce bank erosion and provide for stable sediment storage. The need for additional study and action to fix the sediment problem will be highlighted as a component of the final TMDL implementation plan.
The EPA office of Research & Development also did a “pilot climate change TMDL” on the South Fork of the Nooksack. The report was published
in two separate components, a quantitative and qualitative. The report found climate change will further exacerbate temperature problems, and so actions taken now to reduce temperatures are even more urgent.