The Bull Run watershed is an unfiltered source that produces some of the highest raw water quality of surface water sources in the U.S. Source water quality is routinely monitored at the mouth of the four major tributaries that flow into the reservoirs; the reservoirs and Bull Run Lake; and at the raw water intake. Because the watershed is closed to public entry and has stringent controls on logging, there are no land-use related sources of chemical or microbial contamination.
A Source Water Assessment for the Bull Run water supply was recently completed by the Portland Water Bureau. The assessment identified the geographic area that supplies water to the City of Portland’s Bull Run water system intake and inventoried the potential contaminant sources that may impact the water supply.
The Source Water Assessment was completed to provide information to the Portland Water Bureau’s retail and wholesale customers about the location of the Bull Run source area and the location and nature of any potential contaminants of concern. The assessment was prepared under the requirements and guidelines of the federal 1996 Amendments to the Safe Drinking Water Act (SDWA).
What areas are included in the drinking water protection program area for the Bull Run water supply?
The primary water supply for the City of Portland and its wholesale customers is the Bull Run watershed. This public water system serves a population of about 831,000 citizens. The Bull Run supply is an unfiltered, highly protected source located within the 143-square mile Bull Run Management Unit of the Mt. Hood National Forest in east Multnomah and Clackamas counties, Oregon. The Management Unit is closed to public entry and has a general prohibition on timber harvest through special federal legislation passed in 1996 and 2001. The intake for the system is located on the lower Bull Run River, which drains to the Sandy River and is part of the Lower Columbia River basin. The geographic area providing water to the Bull Run system intake extends upstream approximately 17 miles in an easterly direction and encompasses an area of 102 square miles. The boundaries of the Drinking Water Protection Area are illustrated in the figure attached to this summary.
What are the potential sources of contamination to the Bull Run water supply?
The 1996 amendments to the Safe Drinking Water Act require that Source Water Assessments identify any contaminants of concern and their points of origin within the drinking water protection area. Because of the Bull Run watershed’s long history of protection afforded by stringent legislative and administrative land-use controls, the only contaminants of concern for the Bull Run water supply are naturally occurring microbial contaminants such as Giardia lamblia, Cryptosporidium, fecal coliform bacteria and total coliform bacteria. These organisms are found in virtually all freshwater ecosystems and are present in the Bull Run supply at very low levels. Sources of Giardia cysts and fecal coliform bacteria in the watershed are limited to warm-blooded wildlife species such as deer, elk, cougar, bobcat, black bear, beaver, and muscrat. Sources of Cryptosporidium oocysts include most mammalian wildlife species as well as some bird species.
What are the risks for our system?
For purposes of the Source Water Assessment, the Portland Water Bureau elected to designate the entire 102-square mile drainage upstream of the intake as a sensitive area. There are no management-related sources of any regulated and unregulated contaminants in the Bull Run watershed. As noted earlier, the only contaminants of concern are naturally occurring sources of microbials. The Bull Run supply consistently complies with all applicable state and federal regulations for source water under the SDWA, including the 1989 Surface Water Treatment Rule filtration-avoidance criteria. No further changes to the legislative-based protections for the Bull Run watershed are necessary at this time. Protections provided by existing legislation, administrative plans, and Forest Service and City policies collectively comprise a program that far exceeds the state’s recommendations for a voluntary-based Drinking Water Protection Plan.