The big issue on the Council Agenda this week is the question of whether to plan to spend $385 million ($700 million after borrowing and paying back interest) to build a filtration plant to treat Bull Run water. Or, to spend about $100 million for an Ultra Violet light treatment. I will post comments about that soon.
A few weeks ago, staff in the Water Bureau kindly gave my staff a tour of the Bull Run Watershed. The following are notes by my assistant Cary Turkon, on what she observed and learned. The Bull Run is closed to travelers, recreation, and tourists, to protect Portland's water source. You can sign up to go on a special tour. Here's some observations to inform you in the meantime.
Bull Run Watershed
by Cary Turkon
The 102-square-mile watershed collects 130 inches of precipitation per year. We use 28% of the water that comes down Bull Run. Portland uses about 90 million gallons per day.
The Powell Butte closed reservoir is the hub of our drinking water system, since both Bull Run water and groundwater get pumped there. There is the same amount of sediment in Powell Butte after seven years as there is in Mt. Tabor’s open reservoir after six months, but the overall amount in both still remains remarkably clean. None of our water from Bull Run has exceeded the limit of debris that would require filtration. Vancouver uses groundwater, so it has more minerals.
Bull Run’s mineral content naturally has less than 10 parts per million (ppm), compared with Evian water which has approximately 200 ppm.
Bull Run water is treated with chlorine, ammonia and sodium hydroxide, to disinfect it. Chlorine is added at 2-3 parts per million. After that the ammonia is added, and these two chemicals form the compound chloramine. This retains residual decontaminants better than either of the two separately, because it is more stable. Sodium hydroxide makes the water more alkaline. Naturally acidic water can corrode pipes, so the Environmental Protection Agency (EPA) requires increased alkalinity as a prevention measure.
Fun stuff – as we went by the conduit project, we learned that the two adjacent bridges were recycled from when the Burnside Bridge was replaced in the early 1900s. Rosalyn Lake was an early 1900s PGE project that diverted water from the Marmot Dam to the Little Sandy River Dam. Rosalyn Lake’s berm was pushed down to fill it in and the project was decommissioned. Look up the story of taking down the Marmot Dam on YouTube!
More fun stuff – there used to be a town called Bull Run for people that built the system. Log booms catch debris in the dams. They’ve used copper sulfate to control harmful algal blooms. It is said that the watershed can expect a fire once every 350 years. Most trees are less than 500 years old, although some patches of trees are over 700 years old.
1851: Portland officially became a city.
1859: Oregon became a state.
1880s: a water committee was formed to find a different water source than the Willamette River. Isaac Smith supposedly worried about goiters to “the fair sex” from the water.
January 1, 1895! Portland started to use Bull Run water
1904: The Trespass Act addressed land claims and grazers. Dr. Joseph Miller lived near Marmot and sued the Forest Service in the 1970s and won using the Trespass Act to exhibit the fact that they were logging illegally. 1993 was the last year that logging took place in Bull Run.
1974 the Safe Drinking Water Act gave the EPA regulatory power to determine standards.
1987, the Groundwater Protection Program was established and amended in 2003.
At the springs below the lake, we learned that stream flow is watched very closely and reported to the United States Geological Survey. Turbidity is measured by Nephelometric Turbidity Units (NTUs) and we were given the example that if this stream reached 2000 cubic feet second-1 (CFS) there would be a 100% chance of reaching over 2 NTUs, which is bad. A small stream goes up to 500 CFS in the winter and as low as 5 CFS in the summer. In the 1996 floods, a very small stream that we saw made it up to 2400 CFS.
We learned that the standards for water are based in the four C’s: Clean, Cold, Cheap, and Constant. Keep erosion low and dirt out of the water. We are a storage limited system.
There are two species in this watershed that are on the Northwest Forest Plan’s Survey and Manage List: the Coastal Giant Salamander and the Columbia Dusky Snail. They have to monitor for these species before they let the lake flow.
Outside the Bull Run, the Columbia South Shore Well Field supplies ground water to supplement Bull Run water in the summer. The Columbia Slough runs parallel to the Columbia River and connects Gresham’s Fairview Lake to the Willamette River. It historically absorbed flood waters from the Columbia River, but human activities – such as agriculture and industry – turned it into a slow moving drainage ditch. The Bureau of Environmental Services, Multnomah Drainage Districts, and other agencies are working to restore ecological health to the Columbia Slough.
A solar array project at the groundwater pump station uses power for the pump station and excess energy goes into the grid system. They have three Aquifer Storage and Recovery (ASR) wells.