RI N Erosion, with Its resultant loss of property Essentially there are three major types of degradation of streams is another major resource These are streambank erosion, lake shoreline management issue. erôsion and field erosion. Streambank Erosion Largely because of the physical characteristics of the streams within the C.L.O.C.A. area, which have abrupt changes in direction and elevation, and because of the erosive nature of surrounding soils, there are numerous areas of severe streambank erosion. A conservative estimate would set the number at more than 150 locations. The Authority has undertaken numerous studies and capital projects in an effort to deal with these problems. This work has centred primarily on problems . affecting the more urbanized areas,' since these tend to be the locations which most effect people and property. Erosion control programs are gradually being implemented on Harmony Creek and Oshawa Creek as a result of the studies. Projects have also been undertaken at numerous other locations as problems are identified and needs arise. Prior to 1982, most erosion control projects were undertaken on public land where the municipality would request assistance. In some cases, the erosion ha the potential to effect private property, while in others only public property was threatened. In 1982, however, the Authority began a program for undertaking small erosion control projects on p rivate property. The need for such a program was long overdue because of the numerous reuests for advice and assistance on the part o private Approxim citizens. This program will be continued in future thir s of years. Ontario shor Eroding bluff along Lake Ontario. Example of severe bank erosion. keshore Erosion ately two- the Lake ,eline withm the C.L.O.C.A. area is suffering from.erosion. Shoreline erosion is a naturally occurring process which results fromwind, rain, and to a large extent wave action on shoreline embankments (bluffs). The amount of land lost to this type of erosion can be excessive. The maximum rate of bank recession recorded in the area is 2.68 metres per year during the' period of 1971 to 1973. Generally, long term erosion rates within the Central Lake Ontario Conservation Authority area seem to be considerably less severe. Controlling shoreline erosion is usually very difficult and expensive. Even expensive control techniques are not al- ways successful. It is fortunate, then, that the C.L.O.C.A. shoreline is to a large extent un-, developed. Much of the land is farmland, some residential areas exist particularly close to the Towns of Whitby and Bowmanville, and the City of Oshawa, with commercial and in- dustrial areas located near the harbour areas. near the harbour areas. At present, the Authority provides technical advice to shore property owners who are ex periencing erosion problems. Fu- ture development of ero- sion prone areas is dis- couraged largely through the Authority's commenting function on draft plans of subdivi- sion and other develop- ment proposals. A shore management study is proposed for 1984 which will pro- vide more detailed in- formation on shoreline hazards, and will in- vestigate various shore- line management op- tions. WATER MANAGEMENT Human disturbancE and development ol lands is often respon sible for a ggravating problems of flooding erosion and water pol lution. When lands are developed, much of the surface area is paved or grassed. This type of surface is much less permeable to rainfall than land with a natural vegetative cover. The result is that during storms, a larger pro- portion of rain falling on developed lands runs off into nearby water- courses. This inereases water levels and velQci- ties in the streams dur- ing storm periods which can aggravaté both flooding and erosion problems. I addition, the extra sediment in streams because of in- creased erosion and pol- lutants which wash off streets into the streams cause decreased water quality. The local munici- palities are responsible or urban drainage. However, the Authority e is responsible for flooc f anderosion control, and - for the conservation o g watercourses. Thus , through the local muni cipalities the Authority deals with drainage problems in urba areas. Recently the Authori- ty- has encouraged municipalities to under- take stormwater management studiestfor developing areas, and has required new de- velopment to in- corporate stormwater management tech- niques when they have been necessary. In practical terms, stormwater manage- ment generally re- quires that certain ac- tions be taken to ensure that new development wil not increase flows in streams and water- courses beyond the pre- development level. This can be done through a variety of mechanisms which generally either increase infiltration of water into the ground, or -delay the discharge d of water into the d stream. f Ponds are one of the most commonly used techniques. Stormwater from a new develop- ment would be chan- i neled to the pond where the outflow would be controlled to ensure that the intensity ofdrunoff did not exceed that which existed in the land's pre-development state. Stormwater manage- ment studies have been undertaken, and the techniques have been implemented at a number of subdivision developments in Whit- by, Oshawa, and New- castle. In addition, three majortstudies have been undiertaken either by the local municipality or by the Authority with municipal assistance. These studies have looked at the Courtice area (completed), the Whitby area (near completion), and Goodman Creek (still ongoing). he watershed plan will investigate the fu- ture direction of storm- water management and other water manage- ment issues. Areas re- quiring future storm- water management and master rainage studies will be identi- fied. In summary, the water management pro- gram will be evaluated in light of the following goals and objectives: "To influence land use activities, maintain the state of public awareness, and ac- quire selected hazard lands in order to minimize the risk to life and damages to property from flood- ing and erosion hazards, and in order to ensure that the de- gree of flooding is not aggravated." "To protect surface and ground waters from pollution and, where possible, to undertake actions to enhance water quali- ty." Field Erosion The removal of vege- tation, often in conjunc- tion with agricultural use of lands, exposes soil to erosive forces. The force of rain drops hitting the exposed soil dislodges soil particles and carries them away as the rain runs off. The exposed areas, when dry, are then subject to wind erosion. Over a period of time, the ero- sion becomes increas- ingly severe so that ve- getation is no longer able to establish itself or the land may become unsuitable for agricul- ture because of the loss of topsoil and the forma- tion of gullies. This type of erosion is the least severe type within the C.L.O.C.A. area. Only a few loca- tions where this kind of erosion is a problem have been noted, pri- marily wiithin the Oak Ridges Moraine. The Authority can provide technical ad- vice for dealing with these problems. A pri- vate lands reforestation program exists through which tree seedlings can be purchased and plant- ed in areas of field ero- sion problems. The watershed plan will evaluate the ero- sion problem and the programs for dealing with it in light of Author- ity objectives. The general objectives with regard to erosion can be summarized as follows: "To influence land use activities, maintain the state of public awareness; and ac- quire selected hazard lands in order to mini- mize the risk to life and damages to pro- perty from flooding añd erosion hazards, and in order to ensure that the degree of flooding is not aggra- vated.' And since a good por- tion of the erosion pro- blem occurs in valley- land areas, the follow- ing objective is also relevant: "To protect the in- tegity of valleylands an associated water- courses within the Authority area." Diverted sec- tion of Soper Creek in resi- dential area. «ý Il amou -