bore observations

Tidal Bore Reports:(most recent at top)
by S.A. Williams
[ Current predicted bore times ]
2006
October 8: Tidal bore observation #117 at Mantua bridge since June 2005. Prediction was for 12:05 ADT ; it was in view down-river at 12:03. Arrival at the bridge was 12:13 ADT (-8 min). Bore activity today was on a strong tide following Full Moon (7th) and 2 days following perigee (6th). The white water wave was quite evident even when it came into view in the distant view of the St Croix River. It fell away a bit at the Herbert-St Croix River merge but soon tumbled again as began to approach the bridge where about 12 people, including son, Kent, from Vancouver, were observing.
The outward current was very slow and calm, but the turn was dramatic both in sight and sound as the 45 to 60 cm bore wave rushed under the bridge. About half the folks on the bridge hurried after me to see the bore as it made the turn above the bridge. It rushing around the "S" turn moments later as we entered the tall marsh grass above the channel. It was definitely an excellent bore. Quality of bore: 7.5 out of 10 at bridge, 9 out of 10 in the channel of the "above-bridge-S-turn". Kent and I went on to see the bore on the Kennetcook river at Scotch Village (my 60th obs there).
An interesting bit of behavour noted: just minutes before the bore came into view, a herd of cattle came down to the pasture edge next to the river channel and remained until the bore passed. About one minute after the bore went upstream, the herd of cattle took off on the run, back up into the pasture.
August 26: Tidal bore observation #116 at Mantua bridge since June 2005. Prediction was for 13:11 ADT ; it was in view down-river shortly after this time. Arrival at the bridge was 13:28 ADT (-17 min). Bore activity today was on a leisurely tide. To be expected tides following New Moon (23rd) at the time of apogee (25th). The tumbling wave was quite evident just before reaching the St Croix-Herbert River merge, where one canoe of people were waiting (they rode the current behind the bore as it went on up the St Croix). The wave did not quite become full front across the channel before reaching the bridge. Most of the folks on the bridge hurried after me to see the bore as it made the turn above the bridge. It was a bit muted as it made the turn but moments later it formed a very nice long lasting bore as it went by most of the observers either at the river edge with me in the tall marsh grass or on the bank by the guardrail. It was definitely a much better bore. Quality of bore: 4 out of 10 at bridge, 7 out of 10 in the channel of the "above-bridge-S-turn". About 12 visitors were present including the family who brought me from Nova East Star Party at Smileys Prov Park. They wanted to see the tidal bore. We went on to see the bore on the Kennetcook river at Scotch Village (my 59th obs there).
The Scotch Village arrival of the bore on the Kennetcook River, put on a good show. As it rounded the turn into view it was a bit lazy but in the minute and a half before the leading front went under the bridge (13:54, 26 min after Mantua B), the show was very good. The bore itself was not very high (only about 20 cm at best) but the divisions made by the divided channel, its twists and the sandbar extending nearly across the river bed made for an interesting display of triple, smaller bores and an interplay of current that set up very vigorous whirlpools. As it went under the bridge, the change in current running upriver was impressive compared to calm outflow water just before the bore arrived. The new current was very turbulent. The show was worth a 7 out of 10. Altogether there were 7 observers present. We returned to the Star Party at Smileys, having watched some of the process of the Moon applying the brakes on our turning planet. The energy that delivers the tidal bore is extracted from Earth's rotation.
August 23: Tidal bore observation #115 at Mantua bridge since June 2005. Prediction was for 11:26 ADT ; it was in view down-river shortly after this time. Arrival at the bridge was 11:39 ADT (-13 min). Bore activity today was leisurely, the New Moon (today) spring tides are being off set by the Moon's apogee on the 25th. It alternated between forming a small tumblingwave front and a falling away to a series of swells at the tide front. It did form a brief full front wave in the few seconds befire reaching the bridge and there was no dispute about the moment the tide changed. It was definitely a much better bore on the turn above the bridge. Quality of bore: 5 out of 10 at bridge, 7 out of 10 in the channel of the "above-bridge-S-turn". About 9 visitors were present including Jack from NY who had a particular interest in the phenomena of the tides the aarea.
August 21: My 114th tidal bore observation at Mantua bridge since June 2005. Prediction was for 9:58 ADT ; it was in view down-river at this time. Arrival at the bridge was 10:08 ADT (-10 min). Bore activity today was a leisurely, low range tide after the quarter Moon and approaching apogee. It alternated between forming a small tumblingwave front and a falling away to a series of swells at the tide front. However, there was a distinct change in the water vigour, transforming the pretide's gentle outflowing current and smooth surface into the immediate upstream push of the incoming tide.Following it was a much stronger current.
Quality of bore: 5 out of 10 at bridge, 7 out of 10 in the channel of the "above-bridge-S-turn". Here, the bore was more impressive: a nice 20 cm tumbling wave front across the full width of river bottom. About 8 other observers were present (from NY and MA, USA) and observed the bore with me at both locations. In the latter case, I advisied them about carefully watching out for the traffic while making the brief, brisk, 1 minute walk along the guardrail to where we could get full view of the tide wave coming around the "S" turn.
I did not check Scotch Village bridge today. (SAW)
August 14: My 113th tidal bore observation at Mantua bridge since June 2005. Prediction was for 15:23 ADT (3:23 p.m.); it was in view down-river, at this time. It arrived at the bridge at 15:29 ADT. Bore activity today was very good; vigorous, a nice tumbling wave front as it approached. It was especially impressive to those who hustled along the guard rail and went out on the marsh grass to see it come around the turn above the bridge (about 1.5 minutes after it went under the bridge). Quality of bore: 7 out of 10 at bridge, 8 out of 10 from "S" channel above bridge. About 15 other observers were present. Several followed me to the 2nd observation from the marsh grass. This tide is two days after the peak of large tides this month (Aug 12), which was one of the larger tides for the year.
The tides were last this large in February and March during the New Moon at/near perigee. September tides will also be large from Sept 8th to 11th, following the Full Moon at perigee (Sept 7th, the second closest perigee of the year, 357 175 km). These will be among the largest tides this year, therefore, excellent days to observe a tidal bore, especially Sept 9th and 10th. (SAW)
April 30: Bore check Mantua bridge: Two days after the peak of the New Moon tide. The bore was spotted as soon as it came into view, down at the far end of the St. Croix channel (about 1.4 km distant) at 13:28, 10 minutes later, at 13:38, a very energetic turning of the tide took place as the bore thrust arrived at the bridge. Time predicted was between 13:18 to 13:38 (13:28). Arrival at the Scotch Village bridge was 13:59.
March 30 and 31: Bore check Mantua bridge: Excellent tidal bore activity both days due mainly to the strong New Moon tides not far from perigee and the river was clear of ice and the runoff was moderate. On the 30th it was predicted to arrive between 11:03 and 11:23; at 11:19 a.m. it went under the bridge. On the 31st it was predicted to arrive between 11:51a.m. and 12:11p.m.; at 12:09 p.m. it went under the bridge. On the Kennetcook River at Scotch Village bridge, the bore arrived at 11:41 a.m.(30th) and 12:36p.m.(31st). A very dramatic and energetic turn of the tide.
January 29: Checked bore on the Kennetcook River at Scotch Village. Based on Mantua prediction of 10:08 a.m. the SVB bore was expected between 10:28 and 10:30 a.m. Actual arrival time was 10:29. It was an energetic bore, having a very definite wave front of 40 to 50 cm as it approached the bridge. Showy currents followed.
I did not check Mantua because I was coming from the Cogmagun River. I had plans to see whether or not a tidal bore could be seen at the Cogmagun bridge on highway #215. The tide had already turned when I arrived at the bridge so I proceeded to the 2nd bridge crossing the river on another side road about 2.5 km upstream. It was a very pleasant morning so I followed the meander of the river downstream on foot from the bridge until I met the tide coming upstream. 9:54 a.m. I met the tide, it took another 10 minutes (10:04) for it to progress up about 700m of meandering channel to the bridge. At no point along the route did I see any wave associated with the changing tide. It just turned the current around on one side of the channel while the other side continued briefly downstream until it was overwhelmed by the rising tide water. A topo map helped me work out that the tide moved up river at 4 to 5 km/h; working backwards, the tide reached the #215 bridge at 9:22 to 9:28. I will use this to judge a future time.
January 20: Predicted bore time at Mantua bridge 14:28 (±10 min). About 14:26, a slight change in the reflection on the river surface seen in the far distance was noted. A subtle white line appeared to be moving in my direction. Prior to this change the water surface was smooth and dark in colour. A Common Merganser that was swimming slightly ahead of the tide front, was creating a bow wave that was more pronounced than the tide's wave.
Actual arrival time of the tidal front at the bridge was difficult to determine. I determined it to be 14:34. There was no bore, not even an elevated ripple to signal the arriveal of the tide. What I noticed was a split in currents: on the north side of the channel (right side of bridge) the dark coloured water (lesser sediment content) was still flowing downstream, but on the south side (on the left) the water was chocolate-coloured (containing more stirred-up sediment) and showing signs of moving upstream under the bridge. It was a very subtle change; it probably would have been missed by an observer not tuned for the event.
Tide change in the upper "S"-bend channel was just as uneventful. Contrary to what one normally observes, there was no sign of any kind of tidal thrust to mark the actual moment when the tide changed. Over several minutes (about 5) I noticed the current gradually lost its downstream flow, replaced by a brief time of disoriented surface motion in a state of relative calm, and slowly signs of an upstream drift began to develop. Also, a gradual change in colour took place: from black-tea to chocolate-brown.
This was the most uneventful tidal reversal I've ever witmessed at this location. Probable factors: 1) taking place within the period of apogee (Jan 17) and Last Quarter Moon (Jan 22), thus a smaller than average tide, 2) a higher than average volume of fresh water runoff coming downstream. Normally on this segment of the Herbert River, the colour for the downstream water outflow is a sediment laden, chocolate-brown; today it was a dark, black-tea colour.
Also of note for this event was the closeness of predictied and actual time: they were only 4 min apart. Usually under these moon conditions with average or low runoff volume, a delay of several minutes separate predicted and actual time.
Observed at Mantua bridge were one in-flight, adult Bald Eagle and 5 or 6 swimming, Common Merganser (at least 3 were males). Did not go to Scotch Village bridge today.
January 13: Predicted bore time at Mantua bridge 9:54 (±10 min). Tidal bore was in view off in the distance down the St Croix River, about 9:48; at 9:57 the tidal pulse had just gone under the bridge. Today, in its approach to the bridge, the incoming tidal surge did not produce a frontal tidal bore wave, instead it was a series of swells (deep water waves). The front of the leading wave had a smooth surface over its peak, with a short crest tumbling over only next to the bank on the right. The leading wave advanced, its peak elevated the water level by about 30 cm. and was followed about a metre behind, by another slightly lower swell, which was followed in a quick procession by about 10 or 12 other swells. Each crest appeared to be successively a bit lower in elevation and closer together. The downhill, outflowing current was abruptly reversed into a more vigourous upstream flow powered by the new incoming tide. On the "S" channel curve above the bridge, there was a small bore produced as the surge of tidal water pushed over a sandbar, however, within about 20 seconds the entive surge became barely noticable, probably being swallowed up (readily absorbed) by the large volume and current of todays outflowing water (the mild weather has been quickly melting any accumulated snow). Today was sunny, a very mild, pleasant morning, calm, +9°C. It is 1 day before Full Moon, 4 days before apogee. Presently the largest tides are with the New Moon.
I drove on to check the tidal bore on the Kennetcook River, at Scotch Village bridge (expected about 10:17, allowing about 20 min after Mantua bridge). A barely observable tidal surge occurred at the bridge at 10:19 (about the least obvious bore I've observed at this location). What appeared to be a wave barely exceeding 15 cm, broke briefly and tumbled along the left bank, just before the bridge. I had to look closely to see the slight surge on the right side of the river channel. A series of standing wave swells formed about a minute after the surge went under the bridge and by then it was obvious that the tide had turned. A sizable sandbar was sticking out of the channel a bit on upstream from the bridge; a more obvious bore front did form when the surge reached the constriction of the bar.
Observed during my time at SVB were 3 adult Bald Eagle and a Red-tailed Hawk. The eagles were quite vocal as they approached and took up a perch in the white pines at the river's edge. I suppose they might have been telling eachother about anticipating some food brought by the incoming tide. The Red-tailed Hawk flew across the river and soared above the line of tne tidal marsh, one primary wing feather was sticking upward at an acute angle from its right wing.
January 6: Tidal bore predicted to arrive at Mantua Bridge: 15:47. Actual arrival time at bridge: 15:48. Strong surge in the form of a string of swells, breaking along the muddy slopes at the channel edge, elevating the surface by about 40 to 45 cm as the tidal front passed. Tidal bore arrived at the Scotch Village bridge at 16:10 as a definite frontal wave, tumbling along its front. Not more than 45 cm high. Very thick fog this afternoon, no wind. Elevated river outflow.
2005: Dec 4: Tidal bore arrival predicted 12:18 p.m., actual arrival observed 12:21 at Mantua bridge. Strong tidal surge but deep outflow still persisted at the bridge, therefore the bore was separated into a series of 30 to 50 cm swells. However, further down river, near where the Herbert and St Croix merge the tidal bore was a definite wall of water, breaking over, perhaps as high as 40 cm.. Two observers from Wolfville were there to observe also. At Scotch Village bridge the bore was much like yesterday. One was well aware that the tide was abruptly changing direction, led by a swell of tidal water rather than a definite breaking wave. The tidal bore surged under the bridge at 12:43 p.m.; December 3: Today's tidal bore was at the Mantua bridge at 11:30 a.m. (prediction 11:28 a.m.). As early as 11:22, it was first seen caming into view in the far distance.; Conditions that would have enhanced the development of the bore today were 1)a peak tide from the New Moon (Dec 1), 2) Moon near perigee(Dec 5), also, 3) the brisk westerly wind running with the tide. The wind was strong enough to create waves on the surface of the downstream flow causing the water to appear as if it were going in the opposite direction. Effectively working against the bore's formation was 1) a fairly strong outflow carrying the runoff from yesterday's rain.
: The surge of incoming tide was very strong, immediately appearing to reverse the flow to a vigorous upstream rush, but the deep water near the approach to the bridge only permitted a series of (5 or 6) large deep water swells to form rather than a raised wall , spilling over at the top. It did develop two tongues of water along each side, next to the mud banks. The tongues were cresting (tumbling over) ahead of the central swells. Immediately the water level was elevated a good 50 to 60 cm with the passage of the tidal front; the upstream current was distinctly swifter than the former downhill flow. At Scotch Village bridge, the Kennetcook bore arrived at 11:53 a.m. The elevated outflow waters of the river from Friday's rain obviously supressed the tidal bore effect. Even though a bore did form momentarily as the tidal surge approached the bridge, it was not as spectacular as it was yesterday. If the nontidal water level drops in the next few hours, tomorrow's bore should be very good because the tidal energy is about the same.
December 2: Tidal bore viewing was very good today! inspite of some rain. Predicted time for arrival was between 10:38 and 10:58 (10:48). It was raining lightly at the time; I could see the tidal wave coming on the distance at 10:39; it went under the bridge at 10:46 a.m. It was packing more energy than yesterday, forming a wave front about 45 to 50 cm high. Because the channel is deeper near the bridge and run off is high the surge was a series of 5 or 6 large swells. The leading one was longest and highest and cresting over in some places. Earlier there were places where the bore was quite elevated and tumbling the full width of the river bed. Lots of energy as the tide surged upriver. I followed it as it went around the "S" bend near the road at 10:48. At Scotch Village bridge, tidal bore arrival was 11:09 a.m. It rushed in with excellent energy, sporting an elevated, tumbling wave front 45 to 50 cm high as it approached the bridge. The north side developed into a series of deepwater swells as the surge encountered deeper outrunning water, while the shallower, south side continued as a single, elevated wave front, tumbling as it surged under the bridge.Lots of sound generated by the rushing current racing upstream. Tomorrow is the peak of this month's tides so the bore should be at its best.. Today's rain will have increased the depth of the outflow by a small amount.

December 1: predicted time for arrival was between 9:52 and 10:12 (10:02); it was in view at 9:55 and went under the bridge at 10:04 a.m. Because of the deeper runoff water the bore at the bridge was a series of deepwater swells, one behind the other, showing good height and lots of energy as the tide surged upriver. At Scotch Village bridge, tidal bore arrival was 10:27 a.m. It rushed in with good energy and a wave front about 40 to 45 cm. high. Lots of sound generated by the current.
November 20: predicted time for arrival 13:22 to 13:35. Actual arrival times Mantua bridge: 13:26; Scotch Village bridge: 13:50. The incomig tidal surge at both sites was quite reduced. Hardly noticable at Mantua bridge. The showiest bore, although not outstanding, was on the "S" turn above the bridge. A small bore formed just before the SV bridge but was hardly noticable at the turn downstream. This was probably the result of elevated water outflow running against a reduced tidal push. We are now 5 days past Full Moon and in 3 days the Moon will be at apogee (farthest moon distance). Another person from the local area had come to see the bore at Mantua . At my suggestion, observed at SV bridge as well.
November 18: predicted time for arrival of the bore was between 11:54 and 12:09. It arrived at 11:56 a.m. The out flow was elevated a bit over yesterday (more rain in the last 24hr). Mantua bore show was quite diminished due to the strong outflow volume and current... .the incoming tidal surge was almost swallowed up by the outflow current , however, it was a different story at SVB on the Kennetcook. The turning of the tide was an excellent show as the tidal bore surged upriver. A series of large swells led the way; some of these were sporting tumbling whitecaps. At the bridge at 12:20 p.m., the two currents were battling it out, with the rush of the incoming tide dominating. Trough to crest height was a good 60 cm. Another spectactor who had been out reviewing his former stompping grounds, stopped to watch and was impressed with the event. I find it difficult to fathom why there should have been such a contrast in the two locations.
November 17: predicted time between 11:09 and 11:26. The tidal surge (bore) arrived at the bridge at Mantua (MB) at 11:16 and at Scotch Village bridge on the Kennetcook (SVB) at 11:40 a.m. This was one day after the Full Moon tidal peak which put a good amount of energy into the tide, however, the outflowing water was quite deep and more vigorous than usual. At MB I had the bore in view at 11:08, entering the Herbert mouth at 11:13 and at the bridge at 11:16 a.m. It was around the "S" turm by 11:18. The bore advancing to the bridge was a sequence of large swells, with the leading one about 60 to 75 cm from trough to crest and breaking along the edges.
At SVB there was an elevated outflow as well. The bore was in view by 11:35 and at the bridge at 11:40 a.m. The fromt of the tide formed up nicely about a minute before the bridge, giving a mix of tumbling wave, swells and cross currents, as well as noise from the advancing tidal current turning about the outflow waters. So, a good tidal bore, but not as showy as a similar tide with lesser outflow.(S.Williams)
November 6: predicted time Mantua bridge:13:21. It was actually observed going under the bridge at 13:27 (Wm. Williams and F. MacE also by visitors from B.C.).
November 5: predicted time Mantua bridge: 12:32. Bore was in view at 12:28 p.m.; it arrived at the bridge at 12:38 p.m. It was a good strong bore. The wave was up to about 50 cm high. It put on a good show as it moved up the "S" turn above the bridge. The bore at Scotch Village was in view at 12:58 and arrived at the bridge at 13:02. It gave an excellent display....good wave front and lots of current noise.

October14: predicted time Mantua bridge: 08:34. Actual 08:38. The downstream outflow was still elevated but only about a third of the quantity of water as on the 10th. The bore was a much better show today. The wave was strong and probably averaged a close 30 cm height at the sides. The centre, due to the deeper water, formed a series of large swells. The reversal of current was quite vigorous. The "S" turn bore was good also (08:40:30). 4 visitors(Washington state). I did not go to check the Kennetcook bore.

October10: predicted time Mantua bridge: 16:28. Actual time observed was 16:34. For the next while the bore arrival time will be close to the predicted time, it may even arrive a few minutes earlier than predicted. This tends to be the situation as lunar perigee is approached (Oct 14), especially when leading up to the larger Full Moon tides beginning about Oct 16th.
Today's tidal bore was not a showy display as it was on the 7th. This was expected due to the high water runoff downstream. The heavy rains of the last 3 days have vastly increased the volume of river outflow. When the incoming tide encounters the deeper water the tidal bore energy is "swallowed up" in the production of deep water waves that appear as swells or wave ripples moving forward rather than a wall of tumbling water. Until water levels in the rivers drop significently, this will probably continue to shape the character of the bore. The current direction noticably switches direction running upstrean inspite of the strong downstrean current. However, the upstream current is noticably less vigorous.
I also discovered that the bore reached the Scotch Village bridge considerably ahead of its usual timing of 20 minutes after Mantua bridge. Today the bore at this bridge went under about 16:45. I would have predicted about 16:53 or 54. Since my observations began at this site in July, this is by far the shortest time interval between the two bores. I would guess that this shows that the bore waves travel faster in deeper water, and it certainly was deeper today. Visitors-6.(Penn, B.C., local)
October 2: predicted time Mantua bridge: 10:47. Actual arrival: 11: 10. A full 23 minutes behind prediction. Behind for the same reasons as yesterday but I suspect that because of New Moon tomorrow and apogee past, it will be nearer to the prediction over the next few days. There was a nice 20 to 30 cm wave at the constriction as it approached the bridge. Then fell away into its assorted deep water waves just before going under the bridge. About 10 visitors.
Arrived at Scotch Village bridge on the Kennetcook at 11:29. a very good show of broad tumbling wave front (averaged 25 to 40 cm ht.)and excellent current with good sound.
October 1: predicted time Mantua bridge: 10:09. Actual arrival: 10: 34. A full 25 minutes behind prediction. Front a foot (30 cm) or less high. Probable reason: Low energy, very low range tide: Last Quarter Moon at apogee.: Arrived at Scotch Village bridge on the Kennetcook at 10:52. Put on a very good show of broad tumbling wave front (averaged 25 to 40 cm ht.)and excellent current with good sound. 2 visitors here on their own (Manitoba)
: Current predicted bore times.; Current tide chart
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