FLOW AND PRECIPITATION MONITORING

FLOW AND PRECIPITATION MONITORING A Discussion Paper in Support of the Development of A Regional Watershed Monitoring Network Prepared By: The Toronto and Region Conservation Authority September, 2000

FLOW AND PRECIPITATION COMPONENT DISCUSSION PAPER Network Analysis 1.0 Water Quantity Indicators 1.1 Flow Data 1.2 Snow 1.3 Precipitation Table of Contents 2.0 Existing Monitoring Activities and Methodologies 2.1 Flow Data - Locations 2.1.1 Total Flow 2.1.2 Mean Base Flow 2.1.3 Mean Daily Flow 2.1.4 Mean Monthly Flow 2.1.5 Mean Annual Flow 2.1.6 Maximum Instantaneous Flow 2.1.7 Minimum Instantaneous Flow 2.2 Snow Data - Locations 2.2.1 Water Equivalent/Depth 2.2.2 Crust Condition 2.2.3 Ground Condition 2.3 Precipitation - Locations 2.3.1 A.E.S. 2.3.2 Municipal 2.3.3 T.R.C.A. 3.0 Considerations For Effective Monitoring Networks 3.1 Principles 3.2 Gaps in Current Monitoring 3.2.1 Stream Gauge Network 3.2.2 Snow Course Network 3.2.3 Precipitation Gauge Network 3.3 Available Methodologies 3.3.1 Stream Gauge Network 3.3.2 Snow Course Network 3.3.3 Precipitation Gauge Network

4.0 Recommended Monitoring Network 4.1 Stream Gauge Network 4.2 Snow Course Network 4.3 Precipitation Gauge Network 5.0 Prioritization and Implementation of Preferred Networks 5.1 Stream Gauge Network 5.2 Snow Course Network 5.3 Precipitation Gauge Network 6.0 Operations and Maintenance 6.1 Stream Flow Monitoring Costs 6.2 Snow Course Monitoring Costs 6.3 Precipitation Gauge Monitoring Costs Appendices: Appendix 1 Appendix 2 Appendix 3 Location Map of the current and proposed network for Flow Gauging and corresponding data base. Location Map of the current and proposed network for Snow Courses and corresponding data base. Location Map of the current and proposed network for precipitation gauges and corresponding data base.

FLOW AND PRECIPITATION COMPONENT DISCUSSION PAPER Network Analysis 1.0 WATER QUANTITY INDICATORS Water quantity is typically reflected by the three phases of the Hydrologic Cycle where water is represented in its liquid or solid state, these being the liquid precipitation state, the solid snow on the ground state and the resultant flow s in our rivers, streams and lakes. Currently, monitoring is undertaken during each of these phases. The function of this analysis is to: - define the existing networks, - determine the questions we need to be able to answer to define the needs of monitoring activities - review the existing networks to determine need/gaps, - integrate the quantity requirements with the other watershed system monitoring requirements, - develop an integrated comprehensive and effective overall monitoring network. 1.1 Flow Data Flow data has been collected within the watersheds of the Toronto and Region Conservation Authority for in excess of 50 years. Gauging of Flow data was originally implemented by the Federal Government to fulfill its international obligations related to the Great Lakes. The gauging of watercourses within our region took an upturn following the flooding from Hurricane Hazel and this expansion was related more to riverine flooding issues. More recently, the Federal and Provincial Governments have been dealing with flow monitoring through a Federal/Provincial cost share management agreement. This agreement reflects cost sharing and different management intent for gauges within the Province while maintaining a single agency approach to operations, maintenance and data monitoring/archival. 1.2 Snow The T.R.C.A. currently monitors snow at a total of eight sites as part of an overall Provincial initiative to measure snow depths and water equivalents and predict snow melt,. The sites were originally selected to give a representative assessment of snow depths, water equivalent and the density of our snow pack across the T.R.C.A. s area of jurisdiction. The current monitoring program of the T.R.C.A. is to measure snow depth, water equivalent and density of the snow pack along with other pertinent snow pack data including crust conditions and underlying soil conditions. This information is measured across the Province at specific times throughout the winter season, usually on the 1st and 15 th of each month. The information is then archived by the Province of Ontario through the Ministry of Natural Resources who publishes a by-monthly Provincial report. The data is used both at the Provincial level and the Authority level to determine the snow melt flood threat on our watersheds. Other users are Ontario Hydro and other Provincial agencies involved in flow issues, including the Ontario Ministry of Agriculture and Food in relation to drought concerns.

1.3 Precipitation The measurement of precipitation is key to the determination of an individual flow event and annual flow measurements. Precipitation data is the most widely used information currently being collected. It is used for weather forecasting, flood forecasting and in municipal infrastructure design.. Precipitation data is used to define structural standards, road and sewer design standards, stormwater management standards and bridge/ culvert design standards. As such, precipitation information is currently collected by Environment Canada (Atmospheric Environment Service), the Conservation Authority and our member regions/municipalities as well as at some academic centres. Precipitation data is currently collected through a variety of measuring devices and to a variety of standards, such as daily and continuous. 2.0 EXISTING MONITORING ACTIVITIES AND METHODOLOGIES 2.1 Flow Data - Locations With Government funding cutbacks at both Federal and Provincial levels in the last decade, the existing Provincial network has been undergoing some significant downsizing. Within the T.R.C.A. s watersheds, a network of 25 flow gauges in 1985 has been reduced to one of 15 sites in 1999 being managed under a Federal/Provincial cost share agreement. The Authority is currently operating six additional sites, the Region of Peel operates one site, the Town of Richmond Hill three sites and the City of Toronto two, with one other site under a cost share with the Authority outside of this agreement. A map showing the current network of stream flow gauge sites is included in Appendix 1. A data base containing information on each monitoring site has also been developed and is included in Appendix 1. Each of the current flow monitoring stations with the exception of the Ganeteskiagon Creek at Brock Road ( site # 31) are operated in a continuous mode, collecting flow information throughout the entire year. The monitoring site at the Ganeteskiagon Creek in the Duffins watershed is only operated during non ice conditions. The Flow monitoring stations are typically situated along the watercourses at locations where a valid hydraulic control exists. A hydraulic control is simply a location where the water levels upstream of the control are not dependant on the water levels downstream such as at a set of rapids or a weir. To gauge the flow at the site, a stage versus discharge curve(rating curve) is developed mathematically or more often by field measurements. The gauge then measures water levels above the control and the flow is determined for each water level using the rating curve. Water levels are recorded using both paper strip chart records or by computer data loggers. The data loggers allow for electronic access to down load information remotely for each site, whereas the paper recorders require the information to be down loaded and archived manually. Streamflow information is currently used by Federal, Provincial and Municipal agencies dealing with issues such as water budgets, flow regulation, low flow augmentation, irrigation, design and flood control purposes.

Where continuous monitoring is being carried out, the following information can be determined. 2.1.1 Total Flow The total flow represents the annual volume of water in cubic metres which passes the gauging station. This is a volume measurement and includes all forms of water which have run over the surface or travelled through the ground to enter the watercourse above the gauging site. This measured flow volume represents the total available input of water through precipitation and snow melt. The total measured flow volume also recognises the losses which take place within the hydrologic cycle associated with evapotranspiration and infiltration. 2.1.2 Base Flow With a continuous record of flow, it is possible to separate the total volume of flow into the portions which represent surface runoff and ground water inputs. The flow volume which reflects ground water inputs is typically defined as the base flow of the watercourse. The base flow tends to be more stable within the watercourse as flow inputs through the ground are generally slower and provide more consistent input. 2.1.3 Mean Daily Flow The mean daily flow is defined as the median flow rate throughout each 24 hour period. It represent the flow that would have 50 % of the volume above and 50 % below this level throughout the day. 2.1.4 Mean Monthly Flow The mean monthly flow is expressed as the average of the mean daily flows within the one month period. 2.1.5 Mean Annual Flow The yearly average of the mean monthly flows is expressed as the mean annual flow. 2.1.6 Maximum Instantaneous Flow The maximum instantaneous flow represents the absolute highest flow recorded during the period of monitoring. In general this is the maximum peak flow recorded during a one year time frame. 2.1.7 Minimum Instantaneous Flow The minimum instantaneous flow represents the absolute lowest flow recorded during the period of monitoring. In general this is the minimum flow recorded during a one year time frame.

2.2 Snow Data - Locations The Authority presently operates eight snow courses where snow conditions are monitored bimonthly during the winter months. Each snow course is made up of ten sample locations layed out in two lines and located at least ten metres apart in a staggered pattern. This pattern accounts for the variation in snow distribution over each site. Snow monitoring involves the use of a calibrated sampler, ( West Montrose Sampler) which is a hollow tube equipped with a cutting edge which is rotated into the snow pack to cut a core of snow down to ground level. Each core is measured for depth and then weighed to determine its water equivalent. The average of each of these snow core readings over the ten locations at each site is recorded as the average depth and water equivalent. The sampler is calibrated to allow for the direct conversion of weight to snow water equivalence. The eight sites were originally sited to reflect the land form and uses within the Authority s watersheds. The eight sites currently monitored are located at: - Albion Hills Conservation Area, - Cold Creek Conservation Area, - Heart Lake Conservation Area, - Claireville Conservation Area, - Boyd Conservation Area, - Bruce s Mill Conservation Area, - Claremont Conservation Area and - Stouffeville Dam A data base and map of the snow course monitoring stations has been developed and is included in Appendix 2. 2.2.1 Water Equivalent/Depth The two components of data measured at each sampling location within each site are the depth of snow and the water equivalent of the snow. The water equivalent is the depth of liquid water contained within the snow pack. The water equivalent within the snow is important in that it allows for an estimate of potential runoff to the rivers, streams and replenishment of ground water. The snow depth allows for the density of the snow pack to be determined. The density is the ratio of water equivalent to depth and represents the ripeness of the snow, or its ability to absorb some of its own melt before allowing runoff from the pack. A snow pack is considered ripe when it can no longer absorb any of its own melt.( 35-40 % range of density) 2.2.2 Crust Condition The presence or absence of a crust on the snow pack along with the thickness of crust is also observed at each snow course. The presence of a crust effects the melt rate and controls whether or not rainfall on the pack is likely to be absorbed or run off. The thickness of crust determines the likelihood of rainfall permeating the surface of the snow pack.

2.2.3 Ground Condition The condition of the ground under the snow is also recorded at each snow course. Whether the soil is dry, wet, unfrozen or frozen also relates to the probability of meltwater entering the ground or running off. 2.3 Precipitation - Locations Precipitation gauging is undertaken at numerous locations within the watersheds of the T.R.C.A., by a number of agencies and for a variety of uses. Gauging ranges from continuous sampling stations where precipitation is measured by tipping bucket or weighing gauges on an annual basis, to seasonal gauges which monitor rainfall on a continuous basis for less than a complete year, to manually read gauges which only record the total rainfall on a daily basis. Several uses for precipitation measurement include determining whether the municipality needs to begin snow removal activities, the analysis of flooding in urban drainage systems, the design of drainage systems, agricultural irrigation needs, flood control facility design and flood forecasting/warning needs. A data base and map have been developed using information collected from the agencies currently monitoring precipitation. The data base and map are included in Appendix 3 2.3.1 A.E.S. The Atmospheric Environment Service of Environment Canada is the agency responsible for monitoring precipitation and archiving data for the federally funded and operated sites within the T.R.C.A. watersheds. At present, A.E.S. operates four continuous gauging sites as noted on our data base and map (Appendix 3) They also coordinate an extensive network of volunteer rainfall observers who record daily rainfall totals and submit the information to A.E.S.. The precipitation information collected is archived and available from Environment Canada. 2.3.2 Municipal Both local and Regional levels of municipalities also record and archive precipitation data across the jurisdiction of the T.R.C.A.. The monitoring devices include both continuous recording( tipping bucket) and total event( standard) gauges. These stations are shown on the map and data base in Appendix 3. 2.3.3 T.R.C.A.. The Authority operates several manually read stations which record only total rainfall, within our area of jurisdiction. These sites are located principally within our active conservation areas, dams and at several locations manned through volunteer readers. These stations are also shown on the map and data base in Appendix 3.

3.0 CONSIDERATIONS FOR EFFECTIVE MONITORING NETWORKS 3.1 Principles The overall network must be comprehensive and effective to ensure that the needs of the RAP reporting process are met, allow for the establishment and reporting on watershed management related policies and programs and be economically viable. To meet these principles, we require an effective monitoring network related to both meteorological and hydrologic data addressing the spatial concerns related to ensuring adequate coverage to record weather related inputs and outputs. The network should also provide sufficient quantity and quality of information to allow for any required analytical work, such as model calibration, flood forecasting, Intensity Duration Frequency curve development or post event review to ascertain remedial needs. A network of snow courses must give both a spatial representation of watershed snow pack coverage and conditions, but also reflect a reasonable representation of land use and form. A network of precipitation stations must provide an adequate degree of spatial coverage, but also reflect the type of data required by the defined users( eg: design, flood issues etc.). The network of stream flow stations should be designed to provide coverage across all watersheds where flow data is required and allow for this information to be reflective of the needs of its users( eg: flood control, design, modelling, land use planning, erosion control, water taking s, climate change, etc.). 3.2 Gaps in Current Monitoring 3.2.1 Stream Gauge Network An initial review of the existing stream flow monitoring network as shown on the location map in Appendix 1 reveals several existing areas where flow data is not presently available. In addition to gaps along watersheds where some gauging currently exists( ie: upper Mimico and Etobicoke), no gauging is presently undertaken on the Petticoat Creek, or any of the small watercourses entering Frenchman s Bay. There is only limited gauging information available from the Oak Ridges moraine area where several gauges have been closed during the last decade due to funding restrictions. While two gauges are located on the upper portions of the Rouge and Little Rouge Rivers, no downstream gauge below the confluence exists. 3.2.2 Snow Course Network The existing network of snow courses across the T.R.C.A. jurisdiction would appear to reflect some spatial gaps in the south central areas ( eg. Don River watershed) and towards the south east area of the T.R.C.A. jurisdiction. Review of the landform/land use being reflected by these stations in terms of their applicability in representing snow conditions requires further analysis.

3.2.3 Precipitation Gauge Network In the location map of precipitation gauging sites, their are several areas where a lack of spatial coverage exists. The watercourses within the Region of Durham have limited coverage. The lower portion of the Town of Caledon and the upper portion of Brampton and the Township of King appear to have limited coverage. 3.3 Available Methodologies 3.3.1 Stream Gauge Network Streamflow information can be collected through a number of procedures: - At locations where a defined stage/discharge relationship has been developed and is not likely to change throughout the monitoring period, data can be measured through the recording of water levels only. - At a site where the stage/discharge relationship may change, flow monitoring is required to define the flow/water level relationship as part of the site monitoring requirements. - Seasonal or short term gauging is also a method widely used to answer site specific design issues or provide information for model calibration at locations where no permanent gauge data is available. - Spot measurements may be undertaken to answer a specific question or facilitate some other monitoring need(ie: water quality). - Baseflow monitoring either continuous, seasonal or as required can be undertaken to develop stream flows. Each of the above types of monitoring can be undertaken with a variety of measuring / archiving devices from paper chart recorders to any number of data loggers and can be remote or telemetered. The costs for each of these monitoring techniques along with their appropriateness depends upon the type and future use requirements for the data being collected. 3.3.2 Snow Course Network At present, the snow data being collected is through field visits and the use of a manual sampling gauge called a West Montrose sampler. This is the most reliable and widely used method of sampling in North America. Other methods are presently being studied and include satellite imagery both infrared and radar. Weighing gauges related to precipitation and heated tipping bucket gauges also provide liquid water equivalent of snowfall.

3.3.3 Precipitation Gauge Network Precipitation is presently measured throughout the area using a combination of weighing gauges, tipping bucket gauges and variations of standard gauges. Current initiatives by Environment Canada in upgrading weather radar to more accurately show rainfall distribution reaching the ground may provide a much wider area of coverage. Current difficulties in using radar information relate to errors in matching the radar to measured amounts known as ground truthing. 4.0 RECOMMENDED MONITORING NETWORK The existing monitoring networks may or may not provide adequate coverage to provide the data necessary to effectively meet the principles outlined in Section 3.1. To develop an efficient and effective monitoring network, an assessment of the existing system must be undertaken. The assessment must look at the need of the user related to the length of data base required, as well as the type of data required. To fulfill this objective, an assessment of our existing networks for precipitation, snow and streamflow was carried out and additional monitoring locations and types were identified. While this assessment of network requirements has received some stakeholder input, additional review may be required prior to the finalization of the network and before the implementation phase begins. 4.1 Stream Gauge Network The existing stream flow network within the T.R.C.A. watersheds was founded to provide data for both Flood Control and overall water management objectives. The majority of the network was constructed in the mid 1960's with only moderate additions and deletions throughout the intervening years. A Federal/Provincial assessment of the network in the early 1990's was based solely upon flood related objectives, resulted in several gauge closures. The network continues to be under stresses associated with limited resources at both the Federal and Provincial level. A review of the existing network shows a total of 33 gauges currently in place as of December 31, 1999 (Appendix 1). All but two of these sites are continuous recording sites operated on an annual basis. Fifteen sites are currently operated under the Federal Provincial cost share process. Two sites are water level recording sites at the T.R.C.A. flood control dams and the Authority operates an additional five sites within the Duffins Creek watershed under an agreement with the Ministry of Environment. The remainder of the sites are operated directly by municipalities or management agreements with Municipalities that involve the Authority. Unlike the monitoring of spatially defined data such as precipitation and snow, the need for flow data is specific to a watershed or sub-watershed. Flow data needs reflect a requirement for information related to issues such as defining flood risk lands unsuitable for future development, stormwater control levels for future land use changes, watershed related strategies, or flood control issues.

Flow data is necessary for effective flood control, particularly flood forecasting and warning. Flow data allows for enhanced calibration of hydrologic modelling which supports better flood forecast capabilities. In addition to the need for flow data when dealing with future land use issues and improved flood forecasting, gaps in flow data availability at the watershed and subwatershed scale tend to impede the development of watershed management strategies and make the setting of attainable targets based upon baseline conditions very difficult. With these flow data requirements in mind, an assessment of the watersheds revealed 22 locations beyond the existing flow gauge network where gauging needs to be considered (Appendix 1). A specific gauge site location in these areas needs to be chosen to ensure suitable hydraulic conditions, allowing for the development of a consistent and stable stage discharge relationship. Careful selections of sites will maximize the applicability of the data collected in achieving the multiple needs of flow data outlined above. The need for each of the proposed sites, in terms of its priority for implementation and the length of time the site should be in place ( eg: 3-5 years), will be subject to further review with stakeholders. Implementation will be based upon need brought about by watershed planning or future development needs 4.2 Snow Course Network The existing network consists of eight snow course stations as shown on in Appendix 2. These sites are monitored bi-monthly during the winter months and data is collected on depth, water equivalency and density of the snow pack. This data is sent to the Ministry of Natural Resources for archival and statistical analysis. The current network allows for the plotting of lines of equal snow depths and water equivalents throughout the region and is designed to be representative of the land form and land use within the watersheds. The current network was also laid out to reflect the historical distribution of snow within the T.R.C.A. s watersheds, reflecting the highest snow amounts within the northwest and northeast areas of the Authority s jurisdiction. Given the changes in land use that have taken place within the watersheds of the T.R.C.A., stakeholders discussed and recommended that an additional three sites be added to the network. These additions will provide a more complete picture of the spacial variation of the snow pack throughout the watersheds and will be more reflective of our expanding urban land uses. The existing network and the location of the proposed additional sites are shown in Appendix 2. Given the relatively small increase in the Authority s Snow Monitoring Network, there is little need to prioritize the sites. T.R.C.A. staff will be able to begin collection of data from these sites beginning in December 2000. Discussions of snow monitoring by stakeholders recommended a 3 year period for these additional sites to determine the need for each site and decide whether or not a longer period of monitoring will be required.. 4.3 Precipitation Gauge Network The existing network consists of 86 sites within or very closely situated to the watersheds within the Toronto RAP. The majority of sites are operated and maintained by the municipalities. The overall network consists of a mix of continuous recording gauges and standard gauges as

shown in Appendix 3. As with snow monitoring, the main issue under consideration when evaluating the precipitation gauge network was the spatial coverage provided by the existing network. Stakeholders also reviewed the possibility of re-distributing precipitation gauges from areas where more than adequate coverage presently exists, however, it was noted that some spatial gaps will still exist after the redistribution takes place. Within the City of Toronto there are a significant number of existing gauges, although some areas of the City remain unmonitored. The re-distribution of some gauges that are clustered together would potentially fill these spacial gaps. The City is currently reviewing part of their precipitation network with the objective of defining a more effective and efficient network. Some consultation on integrating the objectives of the City and the RAP monitoring process has taken place. The precipitation database compilation and summary prepared for this report will also be utilized by the City during their network review. Outside of the City of Toronto, an assessment of the existing network revealed several areas where a lack of spacial coverage is apparent. The area of the upper West Humber River and the area around the headwaters of the Main Humber River were defined as having a lack of coverage. It is recommended that an additional five precipitation gauges be considered within these areas. Although monitored in the past, a lack of current data within the mid ranges of the Upper East Humber points out the need to consider a further two sites in this area. The only other region with less than adequate coverage exists within the eastern area of the Authorities watersheds. An additional five sites have been presented for consideration within this area. The location of all additional precipitation gauge sites is shown in Appendix 3. The frequency with which monitoring occurs in the precipitation network varies according to the Municipalities conducting the monitoring and can be dependant on both the data needs and the amount of available resources. Precipitation monitoring sites are monitored continuously, daily or seasonally depending on need. Currently the City of Toronto gauges are continuously monitored and it is anticipated that this level of monitoring will continue following the redistribution of the City s network. Outside of the City of Toronto, sites within urban and urbanizing areas also tend to require continuous data collected over an extended period. The remaining sites of the precipitation network located primarily in the headwater regions of the basins should be assessed independently to define their requirements through additional consultation with local stakeholders. The prioritization of the rain gauging sites should be based upon either an existing or anticipated need related to either urbanization, water management or RAP needs. 5.0 PRIORITIES AND IMPLEMENTATION OF THE PREFERRED NETWORKS 5.1 Stream Gauge Network Based upon the feedback received to date and a number of internal TRCA discussions, an initial prioritization of flow gauging sites and types has been undertaken. This analysis was

undertaken to define works related to the existing gauging network and for the additional 22 sites put forth through the initial review of needs. The following table outlines the need, type and priority assigned for each of the sites. This table should be reviewed in concert with Appendix 1. Site # (Append. 1) Need for Flow Gauging Table 1 Proposed Flow Monitoring Sites Type of Flow Gauge Length of Monitoring Priority of Site for Implementation 40 Oak Ridges/ Water Budget/ Low Flow/ Modelling Continuous 5 years 1 58 Low Flow Seasonal as required 2 44 Water Budget/ Modelling/Low Flow/WWF* 46 Water Budget/ Modelling/Low Flow/ WWF 47 Water Budget/ Modelling/Low FLOW/WWF 38 Oak Ridges/ Water Budget/ Low Flow/ Modelling Continuous 3-5 years 3 Continuous 3-5 years 4 Continuous 3-5 years 5 Continuous 5 years 6 55 Water Budget/ Modelling Continuous 3-5 years 7 48 Water Budget/ Modelling/low flow 45 Water Budget/ Modelling/ WWF Continuous 3-5 years 8 Continuous 5 years 9 37 Water Budget/ Modelling Continuous 3-5 years 10 57 Water Budget/ Modelling Continuous 3-5 years 11 50 Water Budget / Modelling / Low Flow 56 Water Budget / Modelling / Low Flow 53 Water Budget / Modelling / Low Flow Continuous Continuous 12 Continuous 3-5 years 13 Continuous 3-5 years 14 54 Water Budget / Modelling / Low Flow Continuous 3-5 years / as required 15 43 Water Budget / Modelling Continuous 3-5 years 16 42 Low Flow / Water Budget Continuous 3-5 years 17

41 Low Flow Seasonal as required 18 39 Water Budget / Modelling / Low Flow 51 Water Budget / Modelling / Low Flow 52 Water Budget / Modelling / Low Flow Seasonal as required 19 Continuous 3-5 years 20 Continuous 3-5 years 21 49 Water Budget / Modelling / Low Flow * City of Toronto Wet Weather Flow Management Continuous 3-5 years 22 5.2 Snow Course Network As noted in section 4.2.2., with only an additional three sites recommended to increase the effectiveness of the network, no additional prioritization is required. The sites will be discussed with the appropriate municipal agencies where applicable and the monitoring of these sites will be added to the Authority s program beginning December 2000. 5.3 Precipitation Gauge Network Similar to the process undertaken for adding flow gauges to the monitoring network, an assessment of each proposed precipitation site was undertaken. The results are reflected in terms of the need, type, monitoring time lines and priority for implementation and are presented in the following table. The location of the additional 12 precipitation sites was primarily based upon a visual lack of spatial coverage along with needs for calibration of hydrologic modelling. With the City of Toronto s network currently under review, the siting of any additional gauges within the City will need to be undertaken at a later date, following the City s Wet Weather Flow initiative. The review of the proposed sites listed below should be undertaken in concert with Appendix 3. Table 2 Proposed Precipitation Site s Site # (Appendix. 3) Need for Precipitation Gauging Type of Precipitation Gauge Length of Monitoring Priority of Site for Implementatio n 10009 Oak Ridges Moraine and Water Budget/modelling needs 10005 Oak Ridges Moraine and Water Budget/modelling needs Weighing Gauge Continuous 1 Weighing Gauge Continuous 2

10004 Water Budget / hydrologic Modelling 10006 Oak Ridges Moraine and Water Budget/modelling needs 10007 Oak Ridges Moraine and Water Budget/modelling needs 10011 Oak Ridges Moraine and Water Budget/modelling needs 10010 Oak Ridges Moraine and Water Budget/modelling needs 10012 Oak Ridges Moraine and Water Budget/modelling needs 10003 Water Budget / Hydrologic Modelling 10001 Water Budget / Hydrologic Modelling 10002 Water Budget / Hydrologic Modelling 10008 Water Budget / Hydrologic Modelling Weighing Gauge Continuous 3 Weighing Gauge Continuous 4 Weighing Gauge Continuous 5 Weighing Gauge Continuous 6 Weighing Gauge Continuous 7 Weighing Gauge Continuous 8 Tipping Bucket Seasonal 9 Tipping Bucket Continuous 10 Tipping Bucket Continuous 11 Tipping Bucket Seasonal 12 As noted, the above priorities reflect an assessment by Authority staff and initial feedback from selected municipal staff. The finalized priorities will be subject to further assessment by a wider audience. Priorities may shift due to site specific issues or needs. 5.4 Implementation Upon completion of the final prioritization, funding sources and partnerships will be developed to ensure adequate funds to initiate implementation and to cover operational costs throughout the monitoring period at each site. Potential partners will include, the Federal Government, the Provincial Government, Regional and local Municipal Governments and the private sector( ie: development) where applicable. Once funding is in place, a field assessment will be required to establish the exact location for each monitoring site. This process has taken place for the snow sites, but remains to be completed for the precipitation and stream flow monitoring sites. For the proposed precipitation sites, the technical requirements set forth by Environment Canada should be utilized to assure that the data collected meets minimum standards. The chosen site must also be accessible to allow for maintenance of the equipment and down loading of the data and also be situated in a secure site to prevent theft or vandalism. For the flow monitoring sites, the location must allow for a stable hydraulic control to ensure

the quality of the data, the reliability of the stage discharge relationship, and have reasonable access to allow for construction of the gauge and monitoring requirements. Where feasible, precipitation and flow monitoring could be operated in the same location to allow for a more cost effective monitoring process. Table 3: Summary of Proposed Monitoring Activities for the Flow and Precipitation Component of the Watershed Monitoring Network Indicator Specific Measures Monitoring Program Lead Role Additional Requirements Stream Flow Base flow, total flow, daily flow, monthly flow, annual flow, instantaneous flow Continuation of the 33 existing, routine sites recommended. An additional 22 temporary sites proposed for monitoring for 3 years only, implemented on a rotational period over 9 years in groups of 8, 8 and 6 respectively. Environment Canada (AES) TRCA Local and regional municipalities Equipment cost for 8 sites and installation and maintenance costs for 22 sites unfunded Snow Water equivalent (depth); crust condition; soil condition 11 routine sites proposed, 8 of which are part of existing monitoring activities MNR 3 unfunded sites Precipitation Rainfall 98 routine sites proposed, 86 of which are part of existing monitoring activities. Some redistribution of existing sites recommended. Environment Canada (AES) TRCA Local and regional municipalities 12 unfunded sites 6.0 OPERATIONS AND MAINTENANCE Once installed, the sites will require an operations and maintenance program to ensure the efficient and effective collection and analysis of the data. For the precipitation gauges, the collection of data may be achieved either remotely by telephone if applicable or may require visiting the site on a monthly basis to collect the raw data, format the data and archive the information. In addition to the data collection, maintenance of each site would also occur at the same time. For tipping buckets, cleaning of the unit and ensuring that it is level would form a part of any maintenance program. For the flow monitoring sites, the development of a stage discharge relationship will be a major undertaking at each site. While there are alternative means to develop flow data than through a stage discharge relationship, such a relationship once developed will allow for the site to be re-activated following its initial monitoring time, if required. In addition to the development of

this relationship, down loading of the flow data, formatting, conversion of water levels to flow and archiving will also be required. Maintenance of the site will include the gauge housing, the gauge, and the hydraulic control if necessary. This process should also be undertaken on a monthly basis at each site. To undertake the installation and ongoing operations / maintenance for these sites, a number of costs will exist which are described in the following section. A summary is presented in Table 5. 6.1 Stream Flow Monitoring Costs The initial capital costs for the purchase of a data logger and the construction of a gauge house range from $ 7,000-$10,000 / site, depending upon the gauge type and housing selected. The development of a stage discharge relationship would range from $ 3,500-$ 5,000 / site. The operational and maintenance costs will range from $ 2,500- $ 8,000 / site dependant upon the site, the quality of data needs, and the service provider (ie: private contractor or WSC) Working under the assumption that three years is an adequate period to collect data, we should be in the position to reduce the total number of units and capital expenditure provided the priorities for data need can be spread out over a longer time frame. For example, a total of eight units would require between 8-9 years to accumulate the amount of data flagged in Table 1. A total of eight installations would cost between $ 56,000 to $ 80,000 for the capital investments plus an additional $ 28,000- $ 40,000 to develop the stage discharge relationships, plus an additional $ 60,000 ( assuming a private contractor) to operate, maintain and archive the flow data for the eight sites for the three year period 2001-2004. This represents a capital investment of between $144,000- $180,000 for the first three year period. The second three year period (2004-2007) would be less expensive as the data logger would no longer be required at the next series of priority sites. The costs to develop stage discharge relationships and to operate, maintain and archive the data would still be required at each new site. An estimate for the next three years (2007-2010) for eight new sites would therefore be in the range of $120,000- $156,000, with similar costs associated with the remaining three year period. The decision to retain any of the 22 temporary sites after 2010 would determine annual costs after this time, which would be limited to operations and maintenance. 6.2 Snow Course Monitoring Costs No additional equipment costs are incurred with the addition of the 3 proposed sites to the existing network of 8 snow monitoring sites. The total operational and maintenance costs for the additional sites is estimated at approximately $ 2,500 per year. 6.3 Precipitation Gauge Monitoring Costs Capital costs for a Tipping Bucket are in the range of $ 2, 500 and the costs for a Weighing Gauge are in the range of $ 4,000.

Installation costs for a typical precipitation gauge range from $1,000 to $ 3,500 depending on the site and whether or not telephone access is required. In addition to the capital costs, the operational and maintenance costs would range from $1000 to $2,000 per year per site for staff, equipment time and archival costs. Assuming a two year installation time frame (2001-2002) for the precipitation sites, the costs would range from $33,000 to $ 54,000 per year. Ongoing costs after 2002 would be limited to operations and maintenance.

Table 4 Cost and Product Deliverables From Proposed Monitoring Network Flow and Precipitation Components Year 1 Year 2 Year 3 Year 4 Year 5 Year 6 Year 7 Year 8 Year 9 Costing* Flow* $154,000 $42,500 $42,500 $126,000 $42,000 $42,000 $119,000 $31,500 $31,500 Precipitation* $ 49,500 $ 52,500 $ 18,000 $ 18,000 $ 18,000 $ 18,000 $ 18,000 $ 18,000 $ 18,000 Snow* $ 2,500. $ 2,500. $ 2,500. $ 2,500. $ 2,500. $ 2,500. $ 2,500. $ 2,500. $ 2,500. Deliverables: Flow Addition of 8 new flow gauging sites for a total of 41 active sites Monitoring of the additional 8 sites installed in year 1 Monitoring of the additional 8 sites installed in year 1 Removal of first 8 gauges and installation of 8 new flow gauging sites for a total of 41 active sites Monitoring of the additional 8 sites installed in year 4 Monitoring of the additional 8 sites installed in year 4 Removal of second 8 gauges and installation of 6 new flow gauging sites for a total of 39 active sites Monitoring of the additional 6 sites installed in year 7 Monitoring of the additional 6 sites installed in year 7 Precipitation Addition of 6 new precipitation gauging sites for a total of 92 sites Addition of 6 new precipitation gauging sites for a total of 98 sites Snow Three additional snow measurement sites for a total of 11 sampling sites Administration of data base $ 5,000. $ 5,000. $ 5,000. $ 5,000. $ 5,000. $ 5,000. $ 5,000. $ 5,000. $ 5,000. * Note: Mid Range of costing used where applicable. See Detailed Discussion Paper for ranges

APPENDIX 1: Flow Data - Locations APPENDIX 2: Snow Data - Locations APPENDIX 3: Precipitation - Locations