Study finds Packery Channel will not improve Laguna Madre
5/8/2000

The long-awaited study by PBS&J of possible environmental improvements in Laguna due to construction of Packery Channel has just been released to the public by the Galveston District U.S. Army Corps of Engineers . The study was apparently finished in October, but release has been delayed by pressure from pro-Packery politicians, because the results do not support their wish to build Packery Channel. In fact, the study shows Packery Channel cannot be built under Federal guidelines for environmental enhancement, because the environmental benefits are negative to negligible and the cost of construction is high.

The PBS&J study said that the supply of sand in the Gulf available to fill Packery is about 500,000 cubic yards per year, twice that predicted by the Packery proponents.

PBS&J estimates annual maintenance dredging by using the numbers from Mansfield Pass . They predict an annual dredging and jetty maintenance cost of $292,000 using a dredging cost of $1.50 per cubic yard. Present day costs along the Texas coast are commonly $3.00 per cubic yard for similar projects and will be even higher in the future.

At $3.00 per cubic yard, the annual cost for Packery would be $555,000 per year for dredging and jetty maintenance . It will however, be even higher because the cost was obtained by using the amount of sand dredged from Mansfield Pass. Water flows out of Mansfield Pass most of the time reducing the need for dredging. On the other hand, water will flow into Packery Channel from the Gulf most of the time which increases the rate of filling with sand from the Gulf and will result in more dredging than Mansfield Pass.

Several years ago I predicted maintenance costs would range from $500,000 to $1.5 million per year. An adjustment of PBS&J figures for a realistic cubic yard cost for dredging and for inflow dominance would bring the annual maintenance cost to $3/4 million.

If the project is amortized over a life of 50 years, PBS&J concluded the annual cost would be about $1.3 million per year. For longer jetties, the annual amortized cost would be $2.6 million per year . The larger jetties are necessary if navigation safety is considered important . If 500 Nueces County boats regularly use the pass, that is a yearly cost of $2500-$5000 per boat.

As I predicted, PBS&J found the environmental benefits to be negligible. They predict that in 4 out of 5 years, the pass might INCREASE salinity in Upper Laguna Madre! They found that under conditions of long-term average salinity, " the salinity in the bay was less than that in the Gulf. Therefore the effect of each inlet was to increase the salinity in the bay." The PBS&J study concludes: "Therefore, given the low average annual benefit to be achieved, the probability that an opening to the Gulf can be justified in the project area, according to Federal regulations and USACE policy at the completion of a Feasibility Study, is considered low . If a Feasibility Study were pursued, the probability that an opening at Packery Channel could be justified over the South Alternative is also considered low."

The assumptions used in the PBS&J model studies were designed to show the maximum possible environmental benefit to see if Packery Channel construction could be justified based on environmental benefits. They found the benefits were negligible, relative to the cost and that during many years, the channel would actually increase salinity in Laguna Madre.


Richard L. Watson, Ph.D.
Consulting Geologist