GIS Mapping

A Geographic Information System (GIS) is a computerized tool for mapping and performing analysis. GIS has changed the way we view the geographic world in which we live and the way information is transmitted.

GIS at Toronto and Region Conservation


Hardware is the computer on which a GIS operates. The TRCA uses powerful PC-based computers connected through a Local Area Network (LAN). Large geographic databases are stored on a central server and accessed by desktop clients simultaneously. This structure ensures that mapping and analysis products are consistent and that clients can access updates to data.


GIS software provides the functions and tools needed to store, analyze and display geographic information. The TRCA uses a variety of GIS software including ArcView GIS, MapInfo, PCI Remote Sensing Software as well as Microstation and AutoCAD CAD software.


Data coverage, quality, accuracy and age are all critical in having an effective GIS. The TRCA has numerous data sets related to our business functions. TRCA produces its own GIS data; some originates from a variety of other sources including: local/regional municipalities, the province of Ontario – MNR, MOEE, MMAH, Federal Government and other sources.

Technical Staff

TRCA employs a number of staff involved with GIS and CAD. TRCA GIS staff has demonstrated expertise and experience in Spatial Analysis and Modeling, Cartography, Project Management, Remote Sensing, Programming and Customization, Drafting and Design as well as Database Management.


TRCA’s GIS functions are well entrenched in the business functions of the Authority. GIS provides an essential tool for Property Management, Resource Management, Engineering and Flood Plain Management, Development Services and Enforcement, Marketing and Development, and others.


TRCA has developed key relationships with government and non-government partners in the development of its GIS. Foremost is our relationship with local and regional municipalities in the efficient exchange of digital data for GIS purposes. The provincial and federal governments are also key agencies in the exchange of GIS data. Universities and other non-government organizations and agencies also act as partners in projects and research as it relates to GIS and other TRCA business functions.

How GIS at TRCA Works

TRCA GIS stores information about the watersheds in its jurisdiction as a collection of thematic layers that can be linked together by geography. This simple concept has proven to be a powerful and versatile tool in providing solutions and decision-making support for planning, ecological restoration, flood plain mapping, fisheries management and property acquisition.

Current Projects and Products

GTA Digitial Ortho-Photography

Beginning in 1998, the TRCA initiated a partnership with the City of Toronto and the Regional Municipalities of York, Peel and Halton to acquire new digital ortho-photos for their respective jurisdictions. In April 1999, during exceptionally clear weather, a flight was conducted to photograph TRCA and municipal areas of jurisdiction.

These airphotos were then processed by a mapping company to georeference them and correct them for errors and distortions (ortho-rectify). The resulting product is a stunning set of colour digital air photos at a resolution of 0.5 metres and a horizontal accuracy of + or – 2 metres. This data set represents the most accurate and comprehensive digital data set for the Greater Toronto Area.

City of Toronto Natural Heritage Study

GIS staff and TRCA biologists have been using GIS as an integral tool for the development of a Natural Heritage Strategy for the City of Toronto. Staff is using TRCA’s high-resolution digital ortho-photography to identify and digitize natural habitat across the City. The GIS then is used to analyze the habitat data with relation to surrounding land uses, habitat patch size and shape.

We are also exited about the advent of the use of “pocket sized PCs” for biological field data collection in the project. The TRCA was one of the first users of this new technology in Canada. Biologists have been using Pocket PCs and GIS software (ArcPad) to collect field data automatically georeferenced, thus eliminating the need for field notes and paper maps and the subsequent data input.

This technology is also going to be employed in TRCA’s waterfront monitoring and regeneration activities. The Pocket PCs and ArcPad software, in combination with GPS technology, make for a very efficient GIS data collection system.

Screening Maps

The Development Services Section of TRCA has been working with member municipalities and the GIS group to develop a series of “Screening Maps” to streamline the permit process for TRCA regulations. These maps allow municipal staff to identify which development applications should be forwarded to the TRCA for comment and permits based on a “zone” of environmental interest. This zone includes flood plains, fill regulated areas, environmentally significant areas, valley and stream corridors.

Flood Plain Mapping

TRCA is using its GIS to facilitate the creation of a new set of flood plain maps for its jurisdiction. TRCA’s member municipalities have partnered in this program by providing detailed digital topographic data, which the TRCA then uses as the basis for new flood modeling and subsequently new flood plain maps. New state-of-the-art GIS tools developed through the US Army Corp of Engineers are being used to efficiently integrate HEC II hydraulic models and digital topographic mapping to produce updated flood plain maps.