City of Ottawa Stormwater Management Strategy Newsletter - Spring 2006

Issue 1

PDF Format

Table of Contents

[ top ]

Introduction

Ottawa is a city blessed with the presence of numerous watercourses - from small systems like Sawmill, Bilberry and Graham Creeks, to large river systems like the Rideau, Carp and Ottawa Rivers. As the City’s urban area has expanded over the last 150 years, many of these rivers and streams have been impacted by the ‘side-effects’ of urban growth like increased peak flows and erosion, reduced base flows, degraded water quality, and the loss of aquatic habitat.

Protecting public health and safety through efficient drainage has long been and remains a key objective of managing urban runoff. But over the last few decades, the practice of stormwater management (SWM) has evolved to mitigate the negative impacts of urban growth on the health of receiving watercourses as well.

As the City of Ottawa continues to grow – through both suburban development and infill in the existing urban area – so does the potential for increased impacts on the health of local watercourses. To address these pressures, the City of Ottawa is currently developing a Stormwater Management Strategy. This initiative will provide a long-term plan to guide the safe and effective management of stormwater runoff from urban and urbanizing areas, while sustaining the health of local streams and rivers.

Facilitate this Preserve this
Facilitate this Preserve this
  Avoid this  
Left Arrow Avoid this Right Arrow

[ top ]

What exactly is stormwater and why does it need to be managed?

Stormwater describes the water that runs off the land surface when rains – in particular, the runoff that is generated by changes in land use. When formerly forested or otherwise vegetated areas are replaced with pavement and roofs, the amount of rainfall that runs off is greatly increased, while the amount that seeps back into the ground is greatly reduced. This increased volume of runoff caused by urbanization is called stormwater. In addition, stormwater contains urban pollutants washed off from streets, parking lots, and yards.

Untreated, uncontrolled stormwater can threaten property and infrastructure, damage aquatic habitat and limit the recreational potential of local rivers and streams. The practice of stormwater management can mitigate many of these negative impacts.

Study Area
Study Area
Click here to enlarge

[ top ]

Where does the rain go?

Where does the rain go?

Source: A Guidebook for British Columbia Stormwater Planning, May 2002

Why does the City of Ottawa need a Stormwater Management Strategy?

The essential challenge of stormwater management today is how to balance the needs of 'human habitat' (protection of public health and safety) with the needs of fish habitat (healthy streams and rivers that support diverse aquatic communities) while ensuring cost-effectiveness in both the long and short terms.

This rather tall order is being addressed in jurisdictions across North America as municipalities struggle with the challenge of meeting stringent legislative requirements, growing citizen demands for environmental protection, continuing growth pressures, increasing scrutiny with respect to the effectiveness of current stormwater management efforts, and the reality of finite financial resources.

The City of Ottawa faces these same challenges. Effectively addressing them requires an integrated, strategic approach that the Stormwater Management Strategy will provide.

[ top ]

Study Process and Schedule:

The SWM Strategy will be developed in three stages:

Stage 1: Existing Conditions (Where are we now?)
Stage 2: Alternative SWM Scenarios (Where do we want to (or have to) be)?
Stage 3: Implementation Plan (How do we get there?)

Stage 1 is currently underway and will focus on providing a ‘snapshot’ of current SWM efforts in the City. This includes the collection and consolidation of a wide range of existing information and data including:

  • Infrastructure
  • Stream health
  • Current spending
  • Existing policies and procedures, etc.

This effort will provide direction and further define the scope of work for Stages 2 and 3 of the study. The overall study (Stages 1, 2 and 3) is expected to be complete by autumn 2007.

Preparation of the SWM Strategy will be carried out as a Master Plan in accordance with the requirements of Phases 1 and 2 of the Municipal Class Environmental Assessment.

[ top ]

Some Stage 1 Findings

Land Use Change and Infrastructure:

SWM....
... keeps beaches open.
... keeps beaches open.

 
... sustains healthy streams.
... sustains healthy streams.

 
... treats urban runoff.
... treats urban runoff.

 
... keeps our feet dry.
... keeps our feet dry.
  • The City owns over 140 SWM facilities having a replacement value of approximately $120 million.
  • Many of the City’s older drainage systems that pre-date the use of SWM discharge directly into streams or rivers.
  • Proposed future land use change is projected to result in a significant increase in impervious areas in a number of the City’s subwatersheds.

Fisheries and Stream Health:

  • Fish populations and the quality of fish habitat vary significantly across the City depending on factors like the extent of urbanization and local geology.
  • The encroachment of development into stream corridors has impacted fish habitat through the loss of riparian vegetation which helps cool stream flows and provides a food source for aquatic life.

Water Quality:

  • In some watercourses, water quality parameters (e.g., phosphorus, bacteria and metals) do not meet Provincial Water Quality Objectives on a regular basis.
  • Water quality data indicate greater impacts on smaller tributaries (e.g., Sawmill Creek) as compared to larger rivers like the Rideau because the percentage of urbanization on a watershed basis is much higher for smaller tributaries. In other words, large rivers with extensive, relatively undeveloped watersheds, are less sensitive than smaller systems to the impacts of urbanization.

Climate and Geology:

  • Cold winters and varied climate conditions across the City will influence the development of a SWM Strategy.
  • Groundwater discharge (baseflow) to streams is important for supporting fisheries, but varies significantly across the City based upon local geology (the presence of sand or clay or rock, etc.). Maintaining baseflows to streams through infiltration of stormwater needs to be balanced against the potential for groundwater contamination.

Geomorphology/Stream Erosion:

  • The majority of streams in the City of Ottawa are susceptible to erosion. Many other streams have low gradients that result in aggradation (accumulation of sediment that can result in habitat loss, increased flood risk, etc.).

[ top ]

We Need Your Input

Public input will be essential to the development of an effective SWM Strategy. Opportunities for public comment and input will be advertised in local and daily newspapers and via a mailing list being compiled for the study. To be included on the mailing list or provide information for consideration in the development of the SWM Strategy, please contact the Project Manager noted below.

[ top ]

Questions? Comments?

For further details regarding the SWM Strategy, visit ottawa.ca and click on "Public Consultation", or contact:

Darlene Conway, P. Eng.
Project Manager – Stormwater Management Strategy
Planning and Growth Management Department

City of Ottawa
110 Laurier Avenue West, 4th Floor
613-580-2424, ext. 27611
Darlene.Conway@ottawa.ca

[ top ]