function showStreams() {
  for (i = 0; i < Streams.length; i++)  {
      map.addOverlay(Streams[i]);
      map.addOverlay(streamMarkers[i]);
    }
  }

function hideStreams() {
  for (i = 0; i < Streams.length; i++)  {
      map.removeOverlay(Streams[i]);
      map.removeOverlay(streamMarkers[i]);
		}
  }

var Streams = new Array();
Streams[0] = new GPolyline([
  new GLatLng(51.5674860090582, 0.620350067603598),
  new GLatLng(51.5675936830614, 0.620461393354599),
  new GLatLng(51.5676456548868, 0.620687273823182),
  new GLatLng(51.5678031054569, 0.621023893360406),
  new GLatLng(51.568081762338, 0.6218639865997),
  new GLatLng(51.5681444313171, 0.622199057336553),
  new GLatLng(51.5682042998677, 0.622421720391351),
  new GLatLng(51.5682960614029, 0.622606644390381),
  new GLatLng(51.5683634747993, 0.622698917515913),
  new GLatLng(51.5683443451074, 0.622847207910551),
  new GLatLng(51.568325259652, 0.623013776543049),
  new GLatLng(51.5684382704439, 0.62323467308181),
  new GLatLng(51.5685505957053, 0.62349216945581),
  new GLatLng(51.5686199870859, 0.623822662009601),
  new GLatLng(51.5686462754827, 0.624188715125827),
  new GLatLng(51.568647361927, 0.624280024366677),
  new GLatLng(51.5686825205584, 0.624553489894456),
  new GLatLng(51.5687279403977, 0.624826273380843),
  new GLatLng(51.5688804085172, 0.625297852928519),
  new GLatLng(51.5689354503248, 0.625677002781674),
  new GLatLng(51.5690204685652, 0.625929446012209),
  new GLatLng(51.5690421056822, 0.626126999862586),
  new GLatLng(51.5691258465162, 0.626360651640331),
  new GLatLng(51.5691262294552, 0.626539299710567),
  new GLatLng(51.5691160145224, 0.626735309110031),
  new GLatLng(51.5691470682117, 0.626931438664421),
  new GLatLng(51.5692185515267, 0.627375849705842),
  new GLatLng(51.5693001238949, 0.627553960076889),
  new GLatLng(51.5693403964757, 0.6276958869893),
  new GLatLng(51.5694180906424, 0.628312795442858),
  new GLatLng(51.5694993741556, 0.629256347459129) ],
  streamColours[0], 2);

Streams[1] = new GPolyline([
  new GLatLng(51.5664404888254, 0.624450546456613),
  new GLatLng(51.566664617452, 0.624606736268457),
  new GLatLng(51.5667814198412, 0.624730251398054),
  new GLatLng(51.566872375238, 0.62472748802101),
  new GLatLng(51.5669877615617, 0.624796775215347),
  new GLatLng(51.567101838132, 0.624902507711385),
  new GLatLng(51.5671633020791, 0.625154460109495),
  new GLatLng(51.5672634308223, 0.625242373380044),
  new GLatLng(51.5673125312914, 0.625367638855331),
  new GLatLng(51.5673867685167, 0.625438124154919),
  new GLatLng(51.5674226397045, 0.625599546776142),
  new GLatLng(51.5675334407418, 0.625633261573568),
  new GLatLng(51.5675449614832, 0.625723007983449),
  new GLatLng(51.5677025435931, 0.625827977719878),
  new GLatLng(51.5678930001569, 0.626022495987825),
  new GLatLng(51.5681150897297, 0.626234855373402),
  new GLatLng(51.5683332070047, 0.626340496245855),
  new GLatLng(51.5686349030709, 0.626482663646263),
  new GLatLng(51.5687441137431, 0.626554260459788),
  new GLatLng(51.5688734249354, 0.626644024404232),
  new GLatLng(51.5691158687389, 0.626539173944428) ],
  streamColours[0], 2);

Streams[2] = new GPolyline([
  new GLatLng(51.5663483740655, 0.62714809545266),
  new GLatLng(51.5664572941054, 0.627162139209433),
  new GLatLng(51.5665382770232, 0.627177211165085),
  new GLatLng(51.5666173246408, 0.627245522276952),
  new GLatLng(51.5667102388094, 0.627278073622402),
  new GLatLng(51.5667887565505, 0.627328821651391),
  new GLatLng(51.5668686379385, 0.627308865968294),
  new GLatLng(51.5669967612999, 0.627429129189053),
  new GLatLng(51.5671657780693, 0.627407223533703),
  new GLatLng(51.5672278906928, 0.627494081238677),
  new GLatLng(51.5672884171462, 0.627633858248374) ],
  streamColours[0], 2);

Streams[3] = new GPolyline([
  new GLatLng(51.5664678224058, 0.628130835359785),
  new GLatLng(51.5666861655885, 0.628089046985373),
  new GLatLng(51.5667811123596, 0.628051214305806),
  new GLatLng(51.5668264783311, 0.627874306496141),
  new GLatLng(51.5675051137789, 0.627541211034252),
  new GLatLng(51.5677137692821, 0.627625802988701),
  new GLatLng(51.5680609337571, 0.62776235771365),
  new GLatLng(51.568166820827, 0.627779032041612),
  new GLatLng(51.5684869525929, 0.627971037006707),
  new GLatLng(51.5686109783052, 0.627970985002046),
  new GLatLng(51.5687873949803, 0.62804177525775),
  new GLatLng(51.5690142906788, 0.628078568977648),
  new GLatLng(51.5692033337923, 0.628168693784616),
  new GLatLng(51.569255713056, 0.628116833813822),
  new GLatLng(51.5694079447716, 0.628312587611644) ],
  streamColours[0], 2);

Streams[4] = new GPolyline([
  new GLatLng(51.5677482561075, 0.628275562028662),
  new GLatLng(51.5678233523373, 0.628204419101757),
  new GLatLng(51.5678997165101, 0.628045534990153),
  new GLatLng(51.5679493983377, 0.627974675107874),
  new GLatLng(51.5679860926625, 0.627939107763873),
  new GLatLng(51.567999092937, 0.627886210317634),
  new GLatLng(51.5680358764729, 0.627833037805327),
  new GLatLng(51.5680727899634, 0.627762242632762) ],
  streamColours[0], 2);

var streamPositions = new Array();
  streamPositions = [
  new GLatLng(51.5672634308223, 0.625242373380044),
  new GLatLng(51.5688804085172, 0.625297852928519),
  new GLatLng(51.5672884171462, 0.627633858248374),
];

var streamNames = new Array();
  streamNames = ["Hall Brook", "Hunford Brook", "Miles Brook"];

var streamImages = new Array();
  streamImages = ["Hall", "Hunford", "Miles"];

// Creates a  marker whose info window displays the name corresponding
// to the given index.
function createstreamMarker(point, index) {
  // Create an icon for this point using our icon class
  var thisIcon = new GIcon(mapIcon);
  var imageName = "Markers/" + streamImages[index] + ".png";
    thisIcon.image = imageName;

  // Set up our GMarkerOptions object
  var markerOptions = { icon:thisIcon };
  var marker = new GMarker(point, markerOptions);

  GEvent.addListener(marker, "click", function() {
    marker.openInfoWindowHtml(streamNames[index]);
  });
  return marker;
}

// Create Markers with point from streamPositions.js
var streamMarkers = new Array();
for (var i = 0; i < streamPositions.length; i++) {
  streamMarkers[i] = createstreamMarker(streamPositions[i],i);
  }