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Headwater Study

Ecologists are concerned that anthropogenic changes, such as urbanization, in headwater areas can cause degradation in downstream aquatic systems. However, the process of this degradation and how it relates to the natural functions of headwater drainage features is poorly understood and likely underestimated. TRCA, in collaboration with many partners across Southern Ontario, has undertaken a series of studies to better understand these natural functions and begin to address some of the gaps in the science.

We are updating the Interim Headwater Guideline, and we want to hear from you!
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Since 2006, TRCA and partners have been undertaking a series of studies to better understand the natural functions of headwater drainage features. Headwater drainage features are small, temporary streams, swales and wetlands. These studies were undertaken by the study team because agencies and scientists are beginning to recognize that the natural functions associated with headwater drainage features are poorly understood and underestimated. While the functions of perennial headwater streams are fairly well accepted, temporary systems that may flow for only parts of the year are virtually unstudied and unmonitored. Their small size and the fact that they do not necessarily flow year-round, makes them particularly vulnerable to impacts such as piping, channelization, flow diversion, grade lowering and realignment. However, there is a growing body of evidence to suggest that headwater drainage features are important sources of food, sediment, nutrients, and flow to downstream aquatic systems, and they also provide water quality, storage and attenuation functions as well.

Improving our understanding of these systems is critical, and the timing for developing land use policies and guidelines for protecting headwater functions is now. The Greater Toronto Area and surrounding municipalities are expected to grow by 2 million additional people over the next 20 to 25 years. Much of this growth could be concentrated towards the upper reaches of our watersheds where the concentration of headwater drainage features is higher. This growth has the potential to have substantial impacts on our watersheds, hence it is essential that we understand the functions of headwater drainage features such that we can properly protect these important functions.

The following reports, guidelines and presentations are the up-to-date results of TRCA's Headwater Study.

Literature Reviews

 

Literature Reviews

 

Reports to Funders

 

Reports to Funders

  • Report to Oak Ridges Moraine Foundation
  • Report to Lake Simcoe Clean Up Fund

 

Interim Headwater Guideline

 

Interim Headwater Guideline

 

Presentations

 

Presentations

 

Research Results

 

Research

 

Current Projects

 

Current Projects

 

Headwater Monitoring Protocol

  • TRCA is partnering with the Ministry of Natural Resources, Lake Simcoe Clean Up Fund and several other Conservation Authorities to develop and test a monitoring protocol for headwater drainage features. This protocol will eventually become a module in the Ontario Stream Assessment Protocol (OSAP).
  • The draft headwater monitoring protocol is attached below
    Draft Headwater Monitoring Protocol - 15.7MBword document icon

 

Effects of anthropogenic alterations to ephemeral and intermittent headwater drainage features on downstream fish communities

  • TRCA is continuing to partner with Dr. David Barton, a professor in the Department of Biology of the University of Waterloo, to further our scientific understanding of the ecological significance of headwater drainage features (HDFs). This study builds on an earlier study quantifying how organic drift of invertebrates and detritus transported through flow in HDFs contributes indirectly to fish habitat (see above - Masters Thesis Abstract by Odum Idika). Now that we have confirmed through this previous study that this drift does occur, the intent of the current study is to examine how these contributions influence downstream fish productivity. The project is being lead by Julie Hennigar, a Masters student under Dr. Barton's supervision.

Please contact Laura Del Giudice at 416-661-6600 ext. 5334 or ldelgiudice@trca.on.ca for further information on TRCA's Headwater Study.

 

Partners

 

Partners

Region of Peel
Oak Ridges Moraine Foundation
Lake Simcoe Clean Up Fund
Great Lakes Sustainability Fund
Fisheries and Oceans Canada
Region of York
Ministry of Natural Resources
Conservation Halton
Credit Valley Conservation
Remedial Action Plan
Lake Simcoe and Region Conservation Authority
University of Waterloo
Ausable Bayfield Conservation Authority
Upper Thames River Conservation Authority
Southern Ontario Stream Monitoring and Research Team
Ontario Headwaters Insititute
Parish Geomorphic

 

 

Abstract:

Headwater Research: A preliminary investigation into the ecological significance of headwater drainage features in Southern Ontario"
by Odum Idika, Masters Thesis, University of Waterloo

Abstract: Within Southern Ontario urban development is rapidly devouring headwater systems, and this can have significant repercussions to the health of entire river networks. The ecological contributions of headwaters to downstream aquatic systems are poorly understood. The relationships between exported organic material (invertebrates, organic detritus) and land use were examined from 16 headwater systems (13 ephemeral channels, 3 intermittent channels) located in and around the Toronto Region. Drift traps, precipitation and crest stage gauges were installed at each location to capture exported materials, measure rainfall and estimate peak flow, respectively. Samples were collected during runoff events, snow melt or precipitation from March through November 2008. The amount of snow melt or precipitation necessary to trigger surface runoff was found to be highly dependent on land use and antecedent conditions. Invertebrates of aquatic and terrestrial origin were collected, with aquatic animals comprising 43% and 87% of the total from ephemeral and intermittent headwaters, respectively. The mean export of organic materials was 963 invertebrates event-1 (0.65 g) and 32.0 g of plant matter event-1. The amount of materials transported was highly variable among samples (1 - 13,751 invertebrates event-1).

Within ephemeral channels, Annelida, Insecta and Chironomidae were the most numerous aquatic taxa (representing 40%, 24% and 23% of the total number of invertebrates transported event-1, respectively), while Mollusca, Arachnida and Insecta were the most numerous terrestrial taxa (representing 35%, 21% and 16% of the total number of invertebrates transported event-1, respectively). Earthworms contributed 64% of the total invertebrate volume collected event-1. Chironomidae, Crustacea and Trichoptera were the most numerous aquatic taxa collected from intermittent channels (representing 55%, 27% and 8% of the total number of invertebrates transported event-1, respectively), whereas Arachnida, Insecta, and Collembola were the most numerous terrestrial taxa (representing 52%, 19% and 13% of the total number of invertebrates transported event-1, respectively). Trichoptera accounted for 59% of the total aquatic invertebrate volume collected event-1.

Preliminary results suggest that the ecological contributions of headwaters  to downstream systems are considerable and their importance should not be overlooked.

Workshop Presentations:

Workshop Presentations: Preserving Ontario's Headwaters
March 2010, Black Creek Pioneer Village

Agenda - 410K pdf icon

Preserving Ontario's Headwaters, Andrew McCammon, Ontario Headwaters Institute - 1,071K pdf icon

TRCA's Headwater Study, Interim Guideline, and Case Studies, Laura Del Giudice, Toronto and Region Conservation Authority - 7,705K pdf icon

Report to Lake Simcoe Clean Up Fund:

Report to Lake Simcoe Clean Up Fund

Identifying Linkages between Headwater Drainage Feature Condition and Nutrient Transport, March 2011 - 5,218K pdf icon

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We are updating the Interim Headwater Guideline, and we want to hear from you!

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Can it be that I am a fanatic on this subject, or will you agree with me that the time is at hand when we shall come to realize that headwaters are of vital importance. Not only as places of surprising beauty; but also as important factors in the life of the waters below.

---F.E. Hare, Transactions from the American Fisheries Society, 1923

Did you Know?

Headwater basins act as "hydrologically active areas" becoming activated during wet conditions and are linked hydrogeomporphic components of the basin (Gomi et al. 2002)
The spatial extent of headwaters can account for 70-80% of the total catchment area within a watershed (Gomi et al. 2002)
Headwater Streams constitute >50 to 80% of the length of rivers (Schlosser 1982)
90% of a river's flow may be derived from catchment headwaters (Saunders et al. 2002)