In 2011, Medford, Oregon, faced a problem common for cities nationwide. Upon treating sewage from nearly 200,000 people, the city's wastewater treatment plant discharges an average of 17 million gallons of clean -- but warm -- water to the Rogue River every day.
Here's the challenge: The historically cold Rogue River is already warming, and the water the facility is returning to the river could increase its temperature by an additional .18 degree Celsius. Despite being indistinguishable to humans, this increase can have an impact on the salmon and steelhead calling the river home. Warmer rivers have less oxygen and cause eggs to incubate earlier, decreasing survival rates. "Very minor temperature changes in the river can have a dramatic effect on fish populations," said Eugene Weir, project manager with The Freshwater Trust. "The city needed to do something about that to meet its new permit requirement."
To comply with the Clean Water Act, the city had to offset the impact of its warm-water discharge. Fortunately, there was no shortage of options in front of plant employees like Tom Suttle. Cooling towers or chiller could be installed. Water could be held in ponds until it was at the appropriate temperature. Warm water could be reused elsewhere. The problem? "All of those were very expensive," said Suttle. Chillers and storage lagoons can cost $15 million. Reusing water elsewhere could cost $40 million.
The Freshwater Trust offered the city something different; a solution that stood out next to the engineered proposals in terms of both dollars spent and benefits received.The bill for taxpayers? Approximately $6.5 million -- a more than $8 million savings. And the benefits of those trees would extend far beyond producing shade for fish. They filter pollutants like agricultural runoff, reduce carbon in the atmosphere, and provide essential habitat for wildlife. The proposal was accepted, and a first of its kind, regulator-approved water quality trading program was born to meet the temperature requirements. Shade generated from trees planted would be quantified and expressed as credits that the city could purchase.