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Vessel Traffic

Creating an Effects Determination for Vessel Traffic

Sample text:

For in-river projects with expected minimal impacts*:

In our analysis we considered three elements: (1) the existing baseline conditions, (2) the action and what it adds to existing baseline conditions, and (3) new baseline conditions (the existing baseline conditions and the action together). We have determined that vessel traffic added to baseline conditions as a result of the proposed project is not likely to adversely affect ESA-listed species for the following reasons.  

Adding project vessels to the existing baseline will not increase the risk that any vessel in the area will strike an individual, or will increase it to such a small extent that the effect of the action (i.e., any increase in risk of a strike caused by the project) cannot be meaningfully measured or detected.  The baseline risk of a vessel strike within _____ River is unknown.  The increase in traffic associated with the proposed project is extremely small.  During the project activities, a minimal** number of project vessels will be added to the baseline. The addition of project vessels will also be intermittent, temporary, and restricted to a small portion of the overall action area on any given day.  As such, any increased risk of a vessel strike caused by the project will be too small to be meaningfully measured or detected.  As a result, the effect of the action on the risk of a vessel strike in the action area is insignificant.

For projects where additional vessels aren’t expected as a result of the action in the future:

The dredging itself will maintain the navigation channel (other examples: marina reconfiguration, boat ramp repair, etc.) and, as a result, it is expected to enable vessels to travel safely in the area.  Allowing safe passage in the navigation channel is not expected to change the number of vessels that use the action area; thus, preserving the status quo with regard to vessel routes and vessel numbers will not change the risk of a vessel strike.  Any slight increase in risk from altered patterns of use would be too small to be detected or measured, and effects are, therefore, insignificant.

For projects where additional vessels are expected as a result of the action:

The new dredging will increase the vessel capacity of the navigation channel (other examples: new marina, new boat ramp, new ferry terminal, etc.) and, as a result, additional vessels may transit through the action area in the future.  Although the baseline risk of vessel interaction is unknown, any increases in vessel capacity may not directly correlate to more vessels in the action area since active vessels in the action area may move elsewhere, or be retired from use.  At this time, we assume there will only be a slight increase in risk from the minimal** number of additional vessels added to baseline activity in the action area and that any associated increase in risk of a vessel strike would be too small to be detected or measured and effects are therefore insignificant.

*For projects that you do expect impacts because of vessel numbers, please consult the Tappan Zee BiOp for an example of vessel traffic take.

**When actual vessel numbers are available for specific projects, use numbers in analysis instead. 

For offshore projects with expected minimal impacts:

In our analysis we considered three elements: (1) the existing baseline conditions, (2) the action and what it adds to existing baseline conditions, and (3) new baseline conditions (the existing baseline conditions and the action together). We have determined that vessel traffic added to baseline conditions as a result of the proposed project is not likely to adversely affect ESA-listed species for the following reasons.

As described above, the Chatham Stage Harbor FNP shoals about every 3-4 years requiring maintenance.  We propose to continue to use either the CURRITUCK or a mechanical dredge (barge mounted) to maintain the project when needed. Transportation of the dredged material would involve either one vessel (just the CURRITUCK), or three vessels (the barge for the mechanical dredge, a scow, and a tug). Depending on the dredge plan utilized, maintenance dredging can take two to three months to complete.  A conservative estimate of the CURRITUCK or tug and scow vessel trips to the placement site(s) is approximately 88-200.

Chatham Stage Harbor is subject to frequent vessel traffic. Stage Harbor is a multi-use harbor with emphasis on commercial fishing, shellfishing, and recreational boating.  The Stage Harbor Complex (Stage Harbor, Oyster Pond, Oyster Pond River, Mill Pond, Little Mill Pond, and Mitchell River - all use the entrance channel for transit to and from Nantucket Sound) has more than 40 commercial fishing boats, over 1400 moorings (Pers. comm., Chatham Harbormaster, April 2016), and 4 private marinas.

Adding one to three project vessels to the existing baseline will not increase the risk that any vessel in the area will strike an individual, or will increase it to such a small extent that the effect of the action (i.e., any increase in risk of a strike caused by the project) cannot be meaningfully measured or detected.  The baseline risk of a vessel strike along dredge vessel routes is extremely small given water depths preclude whale presence, sea turtle and sturgeon presence is expected to be limited to infrequent transient individuals, and the action area is part of the larger Nantucket Sound where species can be more widely distributed and not concentrated just in the deeper waters of the navigation channel.  The increase in traffic associated the proposed project is extremely small.  During the dredging and placement, only one or two project vessels will be added to the baseline. The addition of project vessels will also be intermittent (every 3-4 years), temporary (88-200 trips, depending on whether it’s the CURRITUCK or a scow and tug), and restricted to a small portion of the overall action area on any day dredging occurs.  Once dredging of the FNP is completed, it will maintain the status quo and not cause an increase in the baseline number of vessels or changes in vessel traffic patterns and thus not change the risk of a vessel strike. Given the nature of the action area, the low baseline risk of vessel strikes in the area, and the extremely small*, intermittent and temporary increase in vessel traffic that would be added to existing traffic in the action area as a result of the project, it is extremely unlikely for a vessel strike in the action area. Given that the action area is in a coastal environment where listed species are able to disperse widely, the risk of vessel strike is extremely unlikely.  As a result, the effect of the action on the risk of a vessel strike in the action area is discountable.

* When actual vessel numbers are available for specific projects, use numbers in analysis instead