Catchment Management Plan - Hunter Water

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2.6 Grahamstown DamCatchmentarea115km 2Damvolume182GL(billion litres)AVERAGEdepthSurfaceareaAnnualrainfall9m 2800ha 1125mm(Williamtown)AreassuppliedLower Hunter,approximately40% ofvolumeLand usebreakdownof catchment39% rural, ruralresidential orurban, 22% StateForest, 39%Hunter Waterfreehold (AppendixA shows how thisland is managed)Populationgrowth forecast2010-2030Current population 53,900 residents primarilyconcentrated in theurban area of Medowie(3,600). 2,000 additionaldwellings (5,600 morepeople) in Medowie by2030Grahamstown Dam is the Lower Hunterregion’s major urban water supply dam,supplying 30-75 per cent (40 per centon an ongoing basis) of our water. Theproportion of water supplied is muchhigher in times of drought. GrahamstownDam itself is located relatively close tothe river at Raymond Terrace (Figure 11).Transfers from theWilliams RiverGrahamstown Dam is classified asan off-river storage facility, storingraw water pumped from the WilliamsRiver at Seaham Weir (1, Figure 11)through the Balickera Canal (2),raised approximately 15 metres atthe Balickera Pumping Station (3) tothen flow through the Balickera Canaland Tunnel into the northern end ofGrahamstown Dam. On average, 50 percent of inflow to Grahamstown Dam ispumped from the Williams.Hunter Water monitors water quality inthe Williams River for nutrients beforetransferring water to GrahamstownDam. Nutrient levels can be assessedrapidly with a permanently installedonline analyser. Like most Australianrivers, the Williams is highly influencedby climatic conditions and isconsequently highly variable in flowand water quality. Flow and waterquality are assessed against pumpingrules to minimise the nutrient loadtransferred to the dam.The Grahamstown catchmentGrahamstown Dam’s small catchmentcontributes the remaining inflow. Thecatchment is primarily located on thenorthern and eastern shores of the dam.To the north of the catchment SevenMile Creek (4) drains small to mediumsized farm allotments, a dirt racetrack,large landscaping supply business anda quarry. The water quality from thenorthern catchment has not been wellcharacterised, but runoff from these landuses typically present some turbidityand nutrient issues. Approximately 75per cent of total catchment runoff comesfrom the northern part of the catchment.Runoff from the east comes directly fromthe urban settlement of Medowie throughthe Campvale Swamps (5). Water ispumped into the dam via the CampvalePump Station (6) and finally spills at theIrrawang Spillway (7).The Medowie catchment is seen asposing the most risk to drinking waterquality as it is an urban catchment. Itcontains all the major risks to drinkingwater quality and is in close proximityto the offtake for Grahamstown WaterTreatment Plant (8).Water quality risk assessments forGrahamstown indicated that pathogens,turbidity, pesticides, organics and algaltoxins, taste & odour compounds werethe principal issues for this system.Grahamstown Dam CatchmentCATCHMENT MANAGEMENT PLAN . ssS . 001 . JUNE201016
12347865Figure 11: Location and extent of Grahamstown catchment, inflows and outflowsCATCHMENT MANAGEMENT PLAN . ssS . 001 . JUNE201017
Page 2 and 3: Table of contentsMessage from the M
Page 4 and 5: Executive SummaryWater supply busin
Page 6 and 7: Part 1: Introduction1.1 DOCUMENT Pu
Page 8 and 9: “Preventive measures by their1.6
Page 10 and 11: Part 2: Our drinking water catchmen
Page 12 and 13: 2.3 A snapshot of Hunter Water’sc
Page 14 and 15: NBarrington TopsNational ParkChiche
Page 18 and 19: 2.7 The Tomago SandbedsCatchmentare
Page 20 and 21: 2.8 The Tomaree (Nelson Bay) Sandbe
Page 22 and 23: 2.10 The Paterson andAllyn RiversCa
Page 24 and 25: 3.1 Element 1: Identify thetop haza
Page 27 and 28: 637 6000williams river2Sinclairs Hi
Page 29 and 30: Using this model it is possible to
Page 31 and 32: 3.2.4 Hunter Water’s visionfor le
Page 33 and 34: Freudenberg (1999) 9 recommendsthe
Page 35 and 36: 3.4.3 Recent improvementsto the mon
Page 37 and 38: 3.5.2 Hunter Water’s vision forca
Page 39 and 40: 3.7 Element 7: EngagE thecommunityO
Page 41 and 42: Appendix A:Items to observe during
Page 43 and 44: Appendix C:The Land newspaper adver
Page 45 and 46: Appendix E:Graphic used to illustra

Catchment Management Plan - Hunter Water

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