What is a Mixing Zone:
A mixing zone is an area of water authorized by the Department of Environmental Conservation (DEC) to receive polluted waste from a point source discharge. This area is also referred to as an “allocated impact zone”. Inside this zone, discharges (or effluent) of toxic pollutants are allowed to exceed the water quality standards set by a state.Where do mixing zones exist?
Mixing zones are commonly permitted for mining, seafood processing plants or wastewater treatment operations. Other facilities may include pulp and paper manufacturers, oil refiners, and hard-rock miners, etc.Mixing zones can be applied to lakes, rivers, streams and other flowing waters. Currently, there is huge concern about mixing zones being permitted in areas of high value such as fresh water spawning waters.
Are mixing zones safe?
Discharges within a mixing zone are considered toxic and may bioaccumulate in the fish, plants and wildlife that use this water.Although the water body as a whole is protected under the Clean Water Act (CWA), the mixing zone area could still be a threat to fish and wildlife habitat.
Who plays a role in authorizing mixing zones in Alaska?
The Alaska Department of Environmental Conservation (ADEC) makes determinations about mixing zones in Alaska with the concurrence of the Department of Natural Resources (DNR). In some instances, the Alaska Department of Fish and Game may also be consulted.The Environmental Protection Agency is responsible for ensuring that all permits through the National Pollution Discharge Elimination System (NPDES) program are consistent with the Clean Water Act. There are 44 states and one territory that implement the NPDES program; however, as of the year 2008 the state of Alaska has not yet authorized the implementation of this program. http://cfpub.epa.gov/npdes/. Mixing zones are still used in Alaska though.
What are the limits of a mixing zone?
Industrial, municipal and other facilities must obtain permits if their discharges go directly to surface waters. There are two types of effluent (discharge) limitations: Water Quality based limits which are derived from state water quality standards, and the less stringent Technology based limits, which do not always meet water quality standards. Since all NPDES permits are required to have effluent limits that will achieve WQS, states generally choose one of two alternatives:1. Apply additional water quality-based discharge limitations that will meet WQS; or
2. Modify the WQS that must be met by the permit. This is done by designating an area at the site of the discharge that will take-on increased levels of pollutants – i.e., authorize a mixing zone.
Where can I learn more about mixing zones?
ADEChttp://www.dec.state.ak.us/water/wqsar/trireview/mixingzones.htm
AK Center for the Environment
http://www.akcenter.org/pages/programs/publiclands/mixing_zones.h
CORMIX mixing modeling program
http://www.cormix.info/applications.php
Cook Inlet Keeper
http://www.inletkeeper.org/2005/TakeAction/alertTemplate.htm
Campaign to Safeguard America’s Waters (C-SAW)
http://www.earthisland.org/project/libraryPage.cfm?pageID=174&subSiteID=6&CFID=14105506&CFTOKEN=99373463
The Alaska State Legislature
http://www.legis.state.ak.us/BASIS/get_single_minute.asp?session=24&beg_line=00273&end_line=00806&time=1323&date=20060405&comm=RES&house=H
National Pollution discharge Elimination System
http://cfpub.epa.gov/npdes/
Compilation of EPA Mixing Zone Documents
http://www.epa.gov/waterscience/standards/mixingzone/files/compendium.pdf
U.S. EPA, Great Lakes
http://www.epa.gov/waterscience/gli/mixingzones/finalfact.html