Final Environmental Statement

A Matrix Analysis of Some Possible Adverse Impacts on the
Environment and Related Uses

In this section, a matrix system is introduced for the purpose

of identifying and analyzing on a tract-by-tract basis those factors resulting from the proposed sale which could impact on the environment and which lend themselves to such an analysis. The matrix itself is simply a device used for displaying the interrelationships of some of the impact-producing factors (on the horizontal axis of each matrix) with coastal activities and resources which could sustain an impact (on the vertical axis of each matrix), and for assigning values to these interrelationships.

1. Purpose The purpose is to analyze some of the possible impacts of the proposed OCS lease sale on the environment using a matrix analytical technique in an attempt to provide the decision-maker and reviewer with an array of factors which must be considered in order to form value judgments concerning the importance of these impacts to the environment.

2. Significant Resource Factors

The matrix analysis examines major

factors which could sustain negative impacts as a result of the

development of the tracts included in the proposed lease sale. Significant resource factors appear on the vertical axis of each matrix

and for purposes of this analysis have been identified and placed into two groups as follows:

Recreation (boating, swimming, water oriented activities other than sport fishing)

Commercial fishing

Sport fishing

3. Impact Producing Factors - The matrix includes two major categories of factors which can impact on significant resources (i.e., natural resource systems, and coastal activities) as a result of the development of proposed OCS oil and gas leases. The Impact-Producing Factors appear on the horizonatal axis of each matrix and have been

identified as follows:

Structures (e.g., platforms, fixed structures and artificial islands)

Oil Spills

1/ Includes parks, sanctuaries, historical landmarks, etc.

Includes marsh, estuary, nursery, and reef areas.

All the tracts proposed for offering in this sale are estimated to be primarily gas prone. Although it is probable that some condensate will be produced with the gas, it is believed the gas from this trend is very dry, and therefore, the quantities of condensate involved will be small.

Consequently, the information presented below concerning

oil spills is not relevant to this proposed sale but is included just the same so that the reader can become familiar with the systematic, tract-by-tract, analysis that is applied to all proposed OCS lease sales which in the past have included both oil and gas prone tracts.

Other impact-producing factors such as debris and pipeline construction cannot be analyzed on a tract-by-tract basis, and therefore are not included in this matrix section.

However, these and other factors

were discussed on the basis of the entire sale in the preceding part

of this section of the statement.

Analytic Procedures

Each impact-producing factor is analyzed on

the basis of (A) its potential magnitude and persistence which we have termed its importance, and (B) its proximity to high value resources or coastal activities/multiple-uses. A series of scales have been devised

for the purpose of assigning a range of values consisting of importance and proximity to each impact producing factor. These scales together with definitions and discussions are presented below.

Under some conditions, offshore structures have an adverse effect

on commercial fishing activities.

Depending on currents and underwater

obstacles an offshore structure can remove areas of trawling and purse seining waters. Heavy concentrations of platforms can make trawling and purse seining difficult.

in general.

Oil and gas platforms pose a hazard to commercial fishing and boating Directional drilling from outside shipping lanes, however, can be used to developed tracts lying partially in shipping

lanes.

An estimate of the importance of the impact of structures on the environment consists of two factors: 1) quantity--in this case it is estimated that all tracts 5,000 acres or more in size will average three structures per tract, even though some tracts may never be developed, and 2) time--all structures will remain on site for an average period of 15 to 20 years.

The same two factors for estimating the importance of oil spills on the environment are as follows: 1) quantity--our analysis is based on all spills of 1,000 bbl. or more, and 2) time--based on past experience the oil itself may remain in contact with, or a hazard to, the environment for a period of 1 to 90 days.

A scale indicating the importance structures and oil spills pose to significant resources or coastal activities/multiple-uses follows: