2.2 Historical data
Collating existing information on the hydrogeology, water quality and ecological status of any waterways that may receive mine drainage discharge is a critical first step in being able to determine the potential impact of that discharge. In particular, where proposed new mine operations overlap or are adjacent to historical mines, information on drainage from historical mines gives an indication of mine drainage chemistry for the proposed operations. However, to ensure these interpretations are accurate, care must be taken to ensure both the proposed and historical mines are in the same geological formation. Different geological formations with different mine drainage characteristics can be adjacent to each other and might have different mine drainage chemistries. Discussion on the use of historical information to provide a qualitative desktop assessment of potential mine drainage chemistry is provided in section 3.3.
Relevant historical information will include geological maps, and existing data on water quality, stream flow, stream ecology and climate. The extent of historical information available will influence the amount and type of baseline data required to be collected.
Historical information and sources of this information include:
- Aerial photos - available from Land information New Zealand (LINZ) at http://www.linz.govt.nz/topography/index.htmx;
- Geological maps - available from GNS Science at http://www.gns.cri.nz/store/publications/maps.html;
- Climate and river flow data - available from NIWA at http://cliflo.niwa.co.nz/ and http://edenz.niwa.co.nz/map/riverflow respectively. These are free databases, although registration is required to download data. Additional river-flow data may be obtained by contacting NIWA directly, and may incur some cost;
- Regional councils may hold relevant information in technical reports, reports supporting resource consent applications, or monitoring data including biological monitoring, flow monitoring and monitoring of water quality and quantity, that can be obtained by contacting the relevant council directly;
- During the development of this framework raw data relating to mine drainage chemistry, stream water quality, and biological monitoring were collated into the ‘DAME’ (Database for Assessment of Mine Environment) database. Please contact the West Coast Regional Council and Environment Southland to discuss accessing this database; and
- Data collected during previous mining operations and exploration are reported to Crown Minerals (Ministry of Economic Development) and are available via the Internet (http://www.crownminerals.govt.nz/cms) or from the Crown Minerals library. Registration is required to access the technical data from the website, although there is no associated cost.
Currently no comprehensive and freely available databases exist for water chemistry, stream algae, or invertebrates. Data on fish distribution are available from NIWA (http://www.niwa.co.nz/our-services/online-services/freshwater-fish-database). Registration is required to access data from this site, although there is no associated cost.
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