What are Headwaters?

First & Second Order Streams

A first-order stream is one with no tributaries, as per the drawing, while a second-order stream starts where two first -order streams converge. First and second-order streams can be permanent, ephemeral (where flow is based on precipitation), or intermittent (where flow occurs when the water table rises).

The OHI defines headwaters as:

  • Surface drainage features, including ephemeral and intermittent streams;
  • Groundwater recharge areas and aquifers;
  • Areas of groundwater discharge and upwelling;
  • Vernal pools, spring-fed ponds, and off-line wetlands; &,
  • First and second-order streams.

While most scientific literature includes third order streams in the definition of headwaters, the OHI has selected a tighter area of focus due to the extent of development, the predominance of private ownership, the lack of current data on the condition of headwaters, and the need for enhanced stewardship for headwater health across southern Ontario.

At the other end of the spectrum, watercourse size grows almost exponentially as stream order increases. Most people know that the Amazon is the biggest river on earth. When asked to guess its stream-order designation, people often think it might be a 23 or a 32.

In fact, it is a 12th order stream.

Why are Headwaters Important?

Headwaters form the basis of the ecological integrity of our watersheds and contribute fundamental social and economic goods and services.

For example, headwaters and their catchment areas, the area drained by small streams:

  • Comprise the majority of both the total surface area and stream length in most watercourses;
  • Contribute the majority of flow to most watercourses;
  • Help regulate that flow – through natural cover, soil type, and surface geology – to both surface and groundwater, thereby reducing both flooding and erosion;
  • Furnish key habitat types for the breeding, feeding, and sheltering of upstream species, thereby habouring a large portion and in many ways the base of a watershed’s biodiversity; and,
  • Nurture downstream ecosystems by providing significant portions of a stream’s nutrients, organic material, and sediment.

In addition:

  • Headwater streams & catchments are as important to terrestrial insects, a key element of the food chain, as they are to aquatic species;
  • Forest cover in headwater areas and along small streams protects local water, and their biodiversity, from thermal heating;
  • Headwaters may be sensitive to small volumes of pollutants; and,
  • Headwater areas may become both less resilient and increasingly important to watershed integrity in a changing climate.

One significant perspective on watershed and headwater health comes from How Much Habitat is Enough, an Environment Canada document that provides non-regulatory guidelines for healthy lands and waters. How Much Habitat suggests the following criteria for healthy watersheds:
• A minimum of 30% natural cover as a high-risk threshold for species diversity and healthy aquatic systems, 40% a medium-risk threshold, and 50% a low-risk threshold;
• The greater of (a) 10% of each major watershed and 6% of each sub-watershed, or (b) 40% of the historic watershed wetland coverage, should be protected and restored; and,
• That both sides of streams should have a minimum 30-metre-wide naturally vegetated riparian area to provide and protect aquatic habitat.
How Much Habitat is Enough also notes that significant impairment in stream water quality and quantity is highly likely above 10% impervious land cover, and can often begin before this threshold is reached.

While Ontario has extensive frameworks for land use planning and watershed management, and some regional targets for natural cover, the OHI is concerned that development is out-stripping the science, policy, and performance frameworks required to maintain the ecological integrity of our watersheds, especially in southern Ontario.

Current Challenges

Broad initiatives for land use planning and watershed management in Ontario include the Planning Act and its accompanying Provincial Policy Statement, the Conservation Authorities Act, the Lakes and Rivers Improvement Act, the Provincial Parks and Conservation Reserves Act, the Greenbelt Act, the Far North Land Use Planning Initiative, various acts on the Great Lakes or other specified bodies of water, a Biodiversity Strategy, and a 1993 document entitled Water Management on a Watershed Basis: Implementing an Ecosystem Approach.

Unfortunately, policy, implementation, and funding gaps are legion, to quote Mary Shelly. Deferring an extensive appraisal of gaps and over-sights to another time and place, key issues include:

  • An absence of provincial guidelines for ecological integrity, like those in How Much Habitat is Enough, underscored by on-going cutbacks to natural science budgets;
  • A lack of balance in the “one-window” approach under the Provincial Policy Statement, wherein the ministry of Municipal Affairs and Housing appears to facilitate development above concerns about natural heritage and watershed management;
  • The absence of a provincial wetland strategy, awkward mechanisms for the identification of significant wetlands and their inclusion in municipal plans, and aberrations such as the sixteen definitions for a wetland in the agencies charged with delivering the Oak Ridges Moraine Conservation Plan;
  • Conflicts between the Drainage Act and the Conservation Authorities Act, as well as conflicts between municipal and conservation authority mandates as a result of having municipalities appoint the members of authority boards. This latter conflict is not so much of commission but of omission – when municipal appointees to CA boards oppose and/or their municipalities refuse to fund sound CA natural heritage initiatives; and,
  • Varied policies regarding the protection of headwaters in different conservation authorities.

From our perspective, Ontario’s historic leadership in watershed management, from the expansion of the role of conservation authorities after Hurricane Hazel through several years following the publication of Water Management on a Watershed Basis, has not received either the policy support nor the resources needed to be a full partner in the shift to land use planning frameworks represented by initiatives such as the Provincial Policy Statement and the Greenbelt and Growth plans.

The OHI considers these issues existential: they are occurring at a time when development is expanding across the landscape, and as we face a changing climate with clear impacts for the hydrologic cycle.

While headlines focus attention upon the possible impacts of a changing climate on Ontario’s forests (fires, pests, and native species) and large bodies of water (low-water impacts on shorelines, shipping, and hydro-electricity), we think it important that Ontario does not overlook the cumulative impacts of a changing climate on our small streams, groundwater, wetlands, the biodiversity they harbour, and the watersheds they nurture.

In fact, we perceive that low water in our small streams may have a more significantly impact on Ontario’s ecologic, social, and economic integrity than potential high or low-water impacts in the Great Lakes.

How can we better protect our headwaters?

The OHI believes that our headwaters and their watersheds should be the object of a provincial commitment to enhance our framework approach to watershed management that could include:

  • Up-to-date natural heritage inventories;
  • The inclusion of key headwater indicators in watershed report cards;
  • Cumulative monitoring, with meaningful, timely, and publicly-accessible data;
  • Improved protective policy and implementation, including efforts to identify and preserve regionally significant headwater areas;
  • Increased funding to and better coordination between natural heritage agencies; and,
  • Expanded sectoral stewardship initiatives.

We pursue these objectives through our three portfolio areas – Research, Education, and Best Practices – and their component programs.