Experimental | Part of a Cooling System

There’s a problem with the Tualatin River watershed-

“The Tualatin River and most of its tributaries have been designated water quality limited under Section 303(d) of the Clean Water Act, and in 2001 the Oregon Department of Environmental Quality issued… requirements for (improving water quality).” Clean Water Services: Revised Temperature Management Plan, page 1.

As part of the requirements, Total Maximum Daily Loads (a measured amount of a specific pollution discharge permitted to enter a river on a daily basis and still meet water quality standards) were specified for temperature. The TMDL dictates an allowable amount that human activities can warm a stream above natural conditions. The Tualatin River watershed was, for the most part, in excess of allowable temperature perameters.

Here’s why-

Run-off (from farm fields, urban landscapes, and logging activities) and waste water treatment effluent, coupled with excess solar radiation reaching water due to inadequate vegetated buffers, collectively cause the Tualatin to be warmer than it would be naturally.

Small ponds, irrigation water return, run-off, and shallow streams that run into the Tualatin River have the potential to introduce waters that are too warm.
Photo: Clean Water Services. Rock Creek Advanced Wastewater Treatment Facility. Post treatment waters also can be the cause of increased river temperatures during summer months.

Warming water in the Tualatin River watershed impacts ecosystems and creates troubling changes:

  • warmer water contains less oxygen- that makes it tougher for Pacific Northwest fish and plant life to survive; negative impact to resident salmonids and anadromous salmonids in particular;
  • food chains are altered;
  • algae growth is promoted;
  • a doorway is opened for the spread of invasive species.

Critical decision: How to cool the Tualatin River Watershed

Choice One- a more traditional approach

  • Man-made engineering: install a $150 million chilling system at the back end of the wastewater processing plant  (cost in 2000, likely much more direct cost to rate payers today).
    • after construction, operation of chiller would require enormous amounts of electricity
    • while solving problem of keeping Tualatin waters cool… power drawn from regional grid would create other environmental problems-
      • bad for carbon releases,
      • Columbia River salmon and other anadromous fish would be effected because much of the power needed would be supplied by hydroelectric facilities,
    • chiller would cool only water immediately downstream-
      • upstream areas where Tualatin River watershed fish go complete their lifecycles.

Choice Two- more of an experimental approach

  • Implement a watershed-scale approach to meet EPA and State regulatory requirements for water quality through the creation of a two part “Thermal load trading program” consisting of:
    • Nature-supported engineering: plant millions of trees to cool the river nature’s way: with shade, combined with…
    • Flow Augmentation from  reservoir during hot summer months.

(Thank you to Rob Emanuel, PhD. Clean Water Services for research assistance with this section.)

Conservation selected over construction

Over a decade ago, officials decided to undertake one of the largest-scale conservation efforts in the nation. In 2004, Clean Water Services was granted a first-of-its-kind municipal, integrated watershed-based National Pollution Discharge Elimination permit.

The two part process was planned:

  • Use shade instead of costly chilling systems to reduce effects of solar radiation;
  • Release deep water from Henry Hagg Lake through pipes to tributary streams to increase flow, and infuse cooler waters into the Tualatin River system during summer months.

The Tualatin River Farm… part of a cooling system experiment

Clean Water Services acquired a 60 acre property- The Tualatin River Farm. This facility is home to “cool” activities targeted to improve the Tualatin River watershed:

  • native plant nursery,
  • working farm with educational programs,
  • transformation of tree plantations to mixed upland forest,
  • habitat enhancement for resident turtles and amphibians,
  • restoration of wetland and riparian habitats.

In addition to the Tualatin River Farm, Clean Water Services partners with many entities. Conservation efforts take a community. Much of the restoration work is done through professional contractors. However, a lot of room is still left for many hands to pitch in. Collaboration among community, municipal, and conservation organizations make large-scale change and long-term stewardship possible. Thirty-five partners achieve what one cannot do alone.

It’s worthwhile to visit the Tree-for-All website to truly appreciate the scope of involvement.The value of planting trees and shrubs up and down the watershed make good agruments in favor of this somewhat experimental method:

1. It cools the water with shade.

2. It provides inputs and food for the aquatic or riparian food web.

3. It provides wood from trees that fall into the creeks or river. This wood helps streams to return to or maintain their normal channel conditions (which are important to the fish and life in them).

4. It provides habitat for myriad songbirds and shore or wading birds.

5. It provides habitat for amphibians, turtles and other herps.

6. It provides habitat for beaver, river otters, other aquatic or riparian mammals.

7. It replaces invasive species with native plant communities.

8. It provides jobs and business growth for people raising and planting the native plants, maintaining the restoration projects.

9. It engages people in improving their quality of their communities.

10. Large assemblages of trees and shrubs actually have a measureable impact on improving air quality for their neighborhoods.

Thank for your inspiration- Rob Emanuel


Weekly Photo Challenge: November 16, 2017 | “Experimental

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