Senate Bill 555, the bill to eliminate mixing zones in bodies of water, appears to be dead in this session of the legislature, although the concerned environmental organizations who promoted it are still very actively pursuing the idea.
To recap, a mixing zone is an area in a river where a DEQ permitted wastewater outfall is used to discharge treated wastewater into the receiving stream. In these zones, residual pollutants in the discharge are allowed to mix with the river water. Outside the permitted mixing zone, water is required to meet federal and state-mandated water quality standards. Within the mixing zone, which may be as small as 10 feet up to several hundred feet around the outfall, some exceedance of non-human related water quality standards is allowed.
The DEQ may allow for this initial dilution of a discharge rather than imposing strict end of pipe pollutant concentration requirements for NPDES water quality permits. This “regulatory” mixing zone may therefore allow for efficient natural pollutant assimilation. Inside the mixing zone, some exceedances of water quality standards may be allowed. At the edge of the mixing zone, water quality standards must be met. The mixing zone must be placed and sized with careful consideration of the impacts to beneficial use. They can only be used as long as the integrity of a water body as a whole is not impaired.
Advocates of a mixing zone prohibition have said that these zones are dangerous and should be marked with buoys and eliminated in the next few years, calling them toxic discharges. In fact, eliminating mixing zones would do very little to further improve water quality. DEQ already has rigid guidelines to prevent mixing zones from presenting any threat to human health or aquatic life.
CCA has supported the Association of Oregon Industries and the Department of Environmental Quality in the continuance of the existing program that evaluates the health of the water body and assigns allowable pollutant loads based on that science, not hyperbole. The existing DEQ programs will also pass a reasonable cost on to dischargers, as loads are adjusted over time. As DEQ states: “DEQ will only allow a mixing zone when it does not harm the river or stream as a whole, kill organisms passing through it, or cause significant risk to human health. “ DEQ also lists 7 major ways in which it is addressing the presence of toxics in the waste stream, including permitting, monitoring and prohibitions against combined sewer overflows.
The proposed program in SB 555 and later SB 532 would create a large fiscal and regulatory burden for cities and industry alike For businesses in the Corridor that discharge industrial wastewater to the City of Gresham or City of Portland, a big consequence would be the likely large increase in sewer rates because the cities will be faced with expensive upgrades to their wastewater treatment plants or at least an in-depth analysis of the feasibility of upgrading. Businesses will likely be forced to upgrade their pretreatment facilities as well or find ways of preventing some runoff from their properties.
CCA is encouraged that the legislature has decided not to pursue this bill. We hope that advocates of such an approach will seek to understand the science of water quality and the impact the immediate elimination of mixing zones would have on all who pay sewer bills or hold discharge permits in the state.
If you have an opinion or question on mixing zones, don't hesitate to call Corky at 503.287.8686. We're here to represent the Corridor.