An Introduction to LT2
In January 2006, The Environmental Protection Agency (EPA) issued a new drinking water rule under the Safe Drinking Water Act called the Long Term 2 Enhanced Surface Water Treatment Rule (LT2).
According to the EPA, “The purpose of the LT2 rule is to reduce illness linked with the contaminant Cryptosporidium and other disease-causing microorganisms in drinking water.” Cryptosporidium is a micro-organism (protozoan) naturally present in bodies of surface water throughout the world. Surface water supplies are particularly vulnerable if, unlike the city’s Bull Run supply, they regularly receive runoff or pollution from human or animal wastes.
Compliance Impacts
Compliance with the LT2 rule would have impacts on two separate parts of Portland’s water system. First, the rule requires the city to provide additional treatment to its Bull Run supply to either remove or inactivate Cryptosporidium. The treatment options available to the city for this include filtration (either traditional or newer micro-membrane technology to remove the parasites), ozonation (the introduction of ozone to water to destroy the Cryptosporidium oocysts) chlorine dioxide (a chemical disinfectant) or ultraviolet radiation (ultraviolet lights irradiate the Cryptosporidium oocysts to prevent them from reproducing which is commonly referred to as inactivation).
Secondly, the rule would require changes to how open finished drinking water reservoirs are managed and operated. The rule requires that water systems with uncovered finished water reservoirs, like those at Portland’s Mt. Tabor and Washington Parks, either cover the reservoirs or provide treatment at the outlets of the reservoirs to either remove or inactive Cryptosporidium and other viruses.
History of Cryptosporidium in the Bull Run
Cryptosporidium can enter surface water via human and animal fecal material. Surface water sources that are exposed to intensive human activities, pollution and animal wastes are likely to contain the parasite.
Portland’s source water, the Bull Run River, is within an exceptionally protected watershed far removed from the types of human activities and pollution that are associated with the presence Cryptosporidium. There are no sewage facilities or cattle anywhere near Portland's source water in the federally protected Bull Run watershed. The wildlife that inhabit the Bull Run Watershed pose the only potential source of Cryptosporidium in the Bull Run. Because of this, the city only rarely detects Cryptosporidium in the Bull Run when it conducts regular water quality monitoring and only at extremely low levels. The city samples Bull Run water for Cryptosporidium on a monthly basis. Cryptosporidium has not been detected in Portland’s drinking water samples since September 2002.
Portland's Response
The Portland City Council committed in January 2005 to pursue alternative forms of compliance for the LT2 rule. Soon after, the city met with EPA officials to encourage the agency to alter the final rule so that it would include alternate approaches that would allow Portland to avoid building additional treatment. When that effort failed, the city filed a legal challenge to the rule in the Washington DC District Court of Appeals in early 2006. In November 2007 the court issued a decision rejecting the city’s challenge and upholding the rule.
In response to the court ruling, the city has been pursuing parallel compliance strategies. Commissioner Randy Leonard has directed the Water Bureau to begin planning and budgeting to achieve compliance with the LT2 rule as written. This includes the design of an ultraviolet water treatment plant in accordance with the rule and implementation of an EPA-approved plan for disconnecting the open reservoirs at Mt. Tabor by December 31, 2015 and by December 31, 2020 at Washington Park. Two enclosed storage tanks are either planned or under construction at Kelly Butte and Powell Butte to serve eastside customers, and an enclosed tank and new main will be installed in Washington Park to serve westside customers.
In addition, Commissioner Leonard has directed the bureau to attempt to obtain a variance to the treatment portion of the rule from the federal EPA. Read more about the variance application process by clicking here.
