Ganaraska River Background Report: Abiotic, Biotic and Cultural Features for preparation of the Ganaraska River Watershed Plan October 2009 Ganaraska River Prepared by Ganaraska Region Conservation Authority The Ganaraska River Background Report: Abiotic, Biotic and Cultural Features was written to document the historical and current conditions of the Ganaraska River watershed. This document creates the foundation of the Ganaraska River Watershed Plan. The Ganaraska Region Conservation Authority would like to thank the many seasonal staff that provided field assistance and the landowners who granted permission to collect data from their property. This document was written by Ganaraska Region Conservation Authority (GRCA) staff members Pam Lancaster, B.Sc., Jenny Dai, M.Eng., Brian Morrison, B.Sc., Mark Peacock, P.Eng., Mike Smith, B.Sc., Ken Towle, M.E.S., and Magdi Widaatalla, M.Sc., P.Geo. for the residents, communities, municipalities and stakeholders of the Ganaraska River watershed. Maps were created by the GRCA GIS Department, Brian Curran, B.Sc., Steve Nowak, B.A. and Jeff Moxley. This document complements Richardson (1944) and the 1966 and 1976 Ganaraska Region Conservation Reports (Department of Energy and Resources Management 1966, Ontario Ministry of Natural Resources 1976). Certain sections of this report have been summarized from peer reviewed or consultant documents, and review and input into this document by committee members, stakeholders and residents occurred in 2009. The Ganaraska Region Conservation Authority envisions that this document will serve to aid in the conservation, enhancement and sustainable management of the Ganaraska River watershed and its resources. ________________________________________________________________ Correct citation for this document: Ganaraska Region Conservation Authority. 2009. Ganaraska River Background Report: Abiotic, Biotic and Cultural Features. Ganaraska Region Conservation Authority. Port Hope, Ontario. The Ganaraska River Background Report: Abiotic, Biotic and Cultural Features Executive Summary The Ganaraska River Background Report: Abiotic, Biotic and Cultural Features documents the historical and current conditions of the Ganaraska River watershed. This document creates the foundation of the Ganaraska River Watershed Plan. It is envisioned that the Ganaraska River Background Report and the forthcoming Ganaraska River Watershed Plan will serve to aid in the conservation, enhancement and sustainable management of the watershed and its resources. The Ganaraska River watershed flows through the Municipality of Clarington, the Municipality of Port Hope, and the Township of Hamilton. Its uppermost headwaters are found in the City of Kawartha Lakes and the Township of Cavan Monaghan (Figure 1). Historic events have shaped the watershed into its present-day condition. Most notable are the effects of dams and settlement patterns caused by the location of road and rail corridors. Today, the watershed supports a population of 11,032 people, a productive agriculture community, and a mix of natural resources and recreational uses. In addition, residents depend on water from the watershed for domestic and economic use, although the residents of Ward 1 in the Municipality of Port Hope rely on Lake Ontario for its source of water. Shaped thousands of years ago by glacial activity, the regional study area lies on Paleozoic bedrock, and its topographic and hydrogeological features include the Oak Ridges Moraine, the Peterborough Drumlin Fields, the South Slope and the Iroquois Plain physiographic regions (Figure 2). Corresponding surficial geology and soils help dictate groundwater flow, aquifer and aquitard location, groundwater, and recharged and discharged areas (Figures 3 and 4). The Ganaraska River drains a total area of 278 square kilometers (km2). The main branch of the Ganaraska River is joined by 10 other tributaries; the largest being the North Ganaraska Branch (Figure 5). Protection of the Ganaraska River watershed has been influenced by surface water studies such as floodplain mapping and hydraulic studies. Regulations are also in place to protect people and property from flood waters, such as the flood that occurred in 1980, and to protect the natural features of the watershed. Flows in the Ganaraska River are generally resilient to stresses such as drought and water use, and adequately provide for aquatic habitat and human use. ___________________________________________________________________ Ganaraska River Background Report: Abiotic, Biotic and Cultural Features i Executive Summary Figure 1: Ganaraska River Figure 2: Physiographic regions ___________________________________________________________________ Ganaraska River Background Report: Abiotic, Biotic and Cultural Features ii Executive Summary Figure 3: Potential groundwater recharge Figure 4: Potential groundwater discharge areas ___________________________________________________________________ Ganaraska River Background Report: Abiotic, Biotic and Cultural Features iii Executive Summary Figure 5: Ganaraska River tributaries Surface water quality as a whole is generally good, with only localized problems. Physical parameters (dissolved oxygen, pH, conductivity and alkalinity) indicate that surface water quality can be resilient to acidification, eutrophication and chemical additions. Chloride concentrations in the Ganaraska River have increased since 1965 at the Peter Street Provincial Water Quality Monitoring Network (PWQMN) station and since 2002 at the Osaca PWQMN station. However, concentrations at the Osaca station have never exceeded 16 milligrams per litre (mg/L) when sampled, and since 2002, concentrations at the Peter Street station have never exceeded 50 mg/L. Total phosphorus exceeds the Provincial Water Quality Objective (PWQO) more often than any other nutrient. Since 1965, total phosphorus has declined at the Peter Street PWQMN station, and there has been a decline since 2002 at the Sylvan Glen and Osaca PWQMN stations. In addition, phosphorus is seen to increase with an increment in stream flow, potentially due to increased surface runoff. Unionized ammonia has been greater than the PWQO of 0.02 mg/L, 28% of the time, as sampled through the Ganaraska Region Water Quality Monitoring Network (GRWQMN). ___________________________________________________________________ Ganaraska River Background Report: Abiotic, Biotic and Cultural Features iv Executive Summary Nitrate-N never exceeded the Canadian Water Quality Guidelines (CWQG) when sampled thorough the GRWQMN or PWQMN. Nitrite-N has only exceeded the CWQG once, and only when sampled through the GRWQMN. Nitrite-N has been declining since 2002 at the Peter Street and Sylvan Glen PWQMN stations. Nitrate-N and nitrite-N are seen to increase as flows increase, potentially due to increased surface runoff. Groundwater quality data is limited on a watershed scale. Information from water well records, the municipal water system and the Provincial Groundwater Monitoring Network (PGMN) indicates that there are naturally occurring groundwater quality parameters that can be aesthetically unpleasing from a human consumption standpoint. However, the quality of surface water is also reflective of groundwater inputs, indicating the groundwater quality in the Ganaraska River watershed is generally good. The Ganaraska River supports a diverse biological community. The fisheries are supported by a sustainable habitat of cold to cool water within the upper two- thirds of the watershed, with a diverse and migratory community in the lower Main Branch of the watershed (Figure 6). Riparian habitats provide buffering capacity to human influences in many of the stream reaches. The Ganaraska River supports a fish community dominated by Brook Trout (Salvelinus fontinalis), Brown Trout (Salmo trutta), Rainbow Trout (Oncorhynchus mykiss), scuplins (Cottidae species), darters (Etheostoma species), and cyprinids. Migratory Chinook Salmon (Oncorhynchus tshawytscha) spawns in the lower reaches. ___________________________________________________________________ Ganaraska River Background Report: Abiotic, Biotic and Cultural Features v Executive Summary Figure 6: Fish communities in the Ganaraska River The terrestrial natural habitat of the Ganaraska River includes forest, meadows and wetlands (Figure 7). At 44%, forest cover is above the commonly used guideline of 30%. However, higher quality interior forest habitat is found in about 43% of the forested areas of the watershed, primarily in the rural landscape. Forests dominate the headwaters and river valleys, and are located on private and public lands. Indicator species such as birds and frogs can help us to understand the health of forest and wetland habitats. Numerous species at risk potentially inhabit the Ganaraska River watershed and therefore should be considered in management planning. Invasive species such as Dog-strangling Vine (Cynanchum rossicum), European Buckthorn (Rhamnus cathartica), and Garlic Mustard (Alliaria petiolata) pose a threat to terrestrial habitat health. ___________________________________________________________________ Ganaraska River Background Report: Abiotic, Biotic and Cultural Features vi Executive Summary Savanna and Thicket 2% Developed 6% Meadow/Grassland 5% Wetland 4% Forest 41% Agriculture 42% Figure 7: Land cover based on ecological land classification The Ganaraska River watershed is not only an important environmental feature to the communities of the watershed; it plays an