Fisheries and Oceans Canada and New Brunswick Department of Transportation

Gate Management Plan to Improve Fish Passage Opportunities at the Petitcodiac River Dam and Causeway

April 01, 2004 to March 31, 2005

Introduction

The trial gate experiment of 1998 and 1999 provided the Departments with information and data on the issue of fish passage. In both years, for extended periods of time during the experiment, the gates were operated such that a minimum of one gate was kept open on a rising tide up to the point where the tidal water elevation was the same as the headpond freshwater elevation. Similar gate management was conducted in November and early December 1999 to optimize adult salmon upstream migration. This was done without impacting the infrastructure or civil works and without further negative impact to fish, fish habitat or the fisheries.

A Gate Management Plan was approved by the Department of Fisheries and Oceans for the period of October to December 1999, February, 2000 to March 31, 2001, April 1, 2001 to March 31, 2002 and April 1, 2002 to March 31, 2003 and April 1, 2003 to March 31, 2004. Those gate management plans were implemented and monitored by NBDOT where DFO and NBDSS monitored fish passage opportunities and presence of fish. This monitoring and DFO expertise on fish passage and fish behaviour allowed this Department to conclude that the improved gate management is providing superior fish passage opportunity to that provided by through the two previously approved fish-ways.

Based on this conclusion and in view of the possibility that there may not be free flow through the gates in 2004/2005, the Department of Transportation and the Department of Fisheries and Oceans agreed on the following temporary procedures to optimize fish passage opportunities. This agreement is limited by the following conditions:

• That saltwater introduction into the headpond would be in the same order of magnitude as what would occur if the two fish-ways were in operation.

• That water level in the headpond would be consistent with the status quo (prior to 1999) range of headpond water level variations.

Gate Management Plan for April 1, 2004 to March 31, 2005

This Gate Management Plan to improve fish passage opportunities at the Petitcodiac causeway is for the period of April 1, 2004 to March 31, 2005.

Improvement to Fish Passage Opportunity

Smelt Migration

Upstream and downstream smelt migration normally occurs at night from mid-April to the end of May. NBDOT will advise Fisheries and Oceans of smelt arrival and will immediately implement the smelt gate management plan. This will normally occur during relatively high freshwater flow and will be done by opening a minimum of one gate for a minimum of 4 hours prior to the expected maximum high tide provided water flows of the Petitcodiac River are sufficient to maintain the headpond levels within normal range.

The closure of the gate(s) will not begin until the tide is at least at the same elevation as the headpond elevation. When the maximum high tide is at about the same as the headpond elevation the gates will be kept open for another hour. Under low maximum high tide, the headpond will be lowered as much as possible to the maximum predicted high tide elevation. Under this condition, the gate(s) will again remain open until an hour after the tide peaks.

The stop log fish-way located downstream of gate number 5 will not be installed, but the vertical slot fish-way will be open for the duration of the smelt migration.

If the gates need to be open for more than 5 hours per night, the operator will open them sooner than described on the rising tide. This is to prevent flushing smelt out of the headpond.

Shad, Striped Bass, Gaspereau

Expected upstream migration is during May and June daylight hours. The vertical slot fish-way will remain opened after the end of the smelt upstream migration. The following gate management will be implemented:

One or more gate(s) will be opened for approximately 4 hours prior to predicted maximum high tide. The duration and the number of gate(s) that will be opened will be at the discretion of the gate operator and will depend on the freshwater input into the headpond in the preceding hours. The gate(s) will be opened during daylight hours. The gate(s) will be manipulated differently for different maximum high tide scenarios.

• Large high tide (maximum high tide higher than 6.3 metres) The headpond is kept as close as possible to elevation 6.1 metres. The closure of the gate(s) begins once the tide reaches the headpond elevation.

• Medium high tide (maximum high tide elevation between 5.5 and 6.3 metres). The headpond is kept as close as possible to maximum high tide elevation. The gate(s) is/are kept opened from 4 hours prior to maximum high tide as a minimum, to 1.0 hours after maximum high tide.

• Neap high tide (maximum high tide elevation is lower than 5.5 metres). The headpond will be lowered as much as possible to the expected maximum high tide elevation. The gate(s) will be kept open for at least 4 hours prior to maximum high tide and for a minimum of 1.0 hours after maximum high tide if the headpond can be lowered to the maximum high tide elevation. Otherwise, the closure of the gate(s) will not begin until after the tide reach the headpond elevation.

Salmon Smolt Downstream Migration

Salmon smolt downstream migration normally occurs from mid-May to the end of June during night-time. DFO will monitor smolt migration and will advise NBDOT district office of the smolt migration who will immediately implement the following gate management plan. Gate manipulation will promote night-time downstream migration to reduce bird predation and to follow smolt behaviour.

A number of gate(s) as required will be opened at night on a receding tide only. The gate(s) will be opened to promote a rapid drawdown “flushing” of the headpond similar to what was done for smolt migration in the last two weeks of May 1998. The headpond will be allowed to fluctuate between elevation 6.1 to 4.5 metres.

Smolt passage through the headpond will benefit from the fluctuation, and smolt survival and acclimation to saltwater will benefit from the large outflow of freshwater into the Petitcodiac estuary.

Potential Conflict between Shad, Striped Bass, Gaspereau and Salmon Smolt Migration

Freshwater flow in June may not be sufficient to operate the gates on a daily basis to promote fish passage as described above. Should freshwater flow not be sufficient, NBDOT district office will contact DFO Habitat Management immediately to resolve fish passage priorities. Operating the gates for fish passage every second or third day or prioritising species depending on extent of passage or peak migration period will be considered.

Gate Operation for the Summer Period

For fish passage consideration, summer is defined as the low flow period starting at the end of the blueback herring upstream migration, normally occurring at the end of June and ending with the first large freshwater flow normally occurring in late September or early October.

The stoplog fish-way located downstream of gate number 5 will not be installed and the vertical slot fish-way will be closed for this period. This will be done to conserve whatever little freshwater is flowing into the headpond. Conserving freshwater flow as described should help bring the headpond to its “normal” level relatively quickly after the end of the spring fish migration. This should also help NBDOT to optimize mud management and should at the same time improve fish passage opportunity.

Surface water flow measurements over the last 4 decades indicate that low flows smaller than 5 cums (cubic metres per second) are the norm for this time period. The low flow for 2001 was in the order of 1 cums. Flows of this magnitude occurred from Mid-July to late October 2001, resulting in a low headpond elevation and high downstream mud elevation.

Gate Management

If there are no juvenile fish present, the gate(s) will be operated as required for mud and pond management.

The gate plan is based on previous fish monitoring studies. The gates will be operated as described below for the downstream migration of juvenile Gaspereau for the period of July 21 to August 31 inclusively. The gate(s) will be operated to keep the headpond between elevation 5.0 to 6.1 metre.

• At night time, open one or more gate on an outgoing tide when the predicted maximum tide is higher or the same elevation as the headpond.

• The gates will not be opened when the maximum predicted tides are lower than the prevailing headpond elevation.

• The gate start of opening will be when the tide is at the same elevation the headpond.

• The gate will be opened for a minimum of 2 hours.

• Gate manipulation for mud flushing only are not allowed during this time period. NBDOT will call a meeting if they believe that mud flushing is required above and beyond what is accomplished by gate opening for fish migration.

NBDOT will immediately call a meeting with DFO to assess the gate operation plan if the headpond water surface elevation gets to be lower than elevation 5.4 metre and cannot be raised as a result of sustained low flow conditions.

Adult Salmon Upstream Migration

The gate management specific to salmon will be as described for shad, striped bass and Gaspereau and will be implemented from the end of summer as described above to the end of migration, which is believed to occur prior to mid-December. The gates will be managed up to that date unless ice conditions or other valid considerations do not allow it.

NBDOT in Moncton will contact DFO Habitat Management should they believe that it be necessary to terminate gate management for salmon migration prior to December 15.

Other Species

It is expected that other species of concern such as eels and trout will be provided with better fish passage opportunities as part of the overall fish passage gate management plan.

Fish Passage During the Winter Months

Tomcod upstream spawning migration may take place from early December to early February, with spawning occurring under the ice in January to February. As a result, the vertical slot fish-way will remain open until February 15.