TANGIPAHOA RIVER, LA. ENTRANCE CHANNEL ENVIRONMENTAL STATEMENT 1. Project description. The Tangipahoa River, La., Detailed Project Report provides for the excavation of an 8- by 100-foot navigation channel between the mouth of the Tangipahoa River and the 8-foot contour in Lake Pontchartrain. The lake bottom has a very gradual slope in the vicinity of the Tangipahoa River and about 1 mile of channel excavation is necessary to provide an 8-foot channel. An increase in length to approximately 13,000 feet would be required for a 10-foot channel and maintenance costs would be increased substantially by the larger channel. Frequently, boats on Lake Pontchartrain must leave the lake to avoid sudden squalls and high winds and seek a secure inland location, preferably the point from which the boat was launched. A larger channel is necessary across the lake bar than would be required inland as a result of wind action which sometimes depresses the water level as much as 2 to 3 feet. A depth of 8 feet is adequate for the anticipated traffic and is about the shallowest depth practicable to maintain with the hydraulic dredging equipment that is normally used to maintain nearby Federal project channels on other tributaries to the lake, such as the Chefuncte River, Bayou Lacombe, and Bayou Bonfouca. These dredges have 18- to 20-inch diameter discharge pipes and draw from 7 to 8 feet. After consideration of channels up to 10 feet deep and up to 125 feet wide, an 8- by 100-foot entrance channel was selected on the basis of the boats to be served and the costs for construction and maintenance of the channel. Section 107 of the River and Harbor Act of I960, as amended by Section 310 of the River and Harbor Act of 1965, provides the authority for the construction of small river and harbor improvement projects not specifically authorized by Congress which will result in substantial benefits to navigation and which can be operated consistently with appropriate and economic use of the waters of the Nation for other purposes, when in the opinion of the Chief of Engineers such work is advisable, if benefits are in excess of the cost. The improvement is economically justified, with a benefit- cost ratio of 2.4 to 1. Currently, plans and specifications have been completed and Federal funds are available for construction. 2. Environmental setting without the project. The Tangipahoa River heads in southwest Mississippi near the town of McComb and flows in a southerly direction for a distance of about 110 miles to its mouth in the northwest portion of Lake Pontchartrain. The river basin has a drainage area of about 790 square miles, and Tangipahoa River provides about cne-fifth of the total inflow into Lake Pontchartrain. Tangipahoa River, La. Environmental Statement The project area is located within the central gulf coastal plain. Specifically, the area is located in the swamplands on the northwest shore of Lake Pontchartrain between the Pleistocene uplands and the lake. The physiographic features include the flat swamplands, sinuous river course, shell beaches along the shoreline, and the lake. Relief in the area is slight except at the shoreline where some shell middens reach a maximum of +5 feet m.s.l. (mean sea level). The Tangipahoa River Basin is almost entirely within Tangipahoa Par;*-Sh» La., and Pike County, Miss. These two areas had a total population of 94,494 in 1960. The principal cities are Hammond, La., and McComb, Miss. The six parishes bordering on Lake Pontchartrain— Orleans, Jefferson, St. Charles, St. John the Baptist, Tangipahoa, and St. Tammany— had a total population of 974,029 in 1960 which included most of the metropolitan area of New Orleans. Agriculture is a major contributor to the economy of the area. Dairy products comprise over 50 percent of the value of all farm products sold. Poultry, fruits and vegetables, and horticultural and forest products are next in order of value followed by miscellaneous field crops, such as corn, sorghums, hay, cotton, and legumes. Strawberries are the major fruit crop. Nearly all of the strawberries grown in Louisiana are produced in this basin and in several stream basins to the west. Pine forests occupy much of the basin and provide a large source of pulpwood and saw timber. Woodland management and reforestation are carried out over extensive areas in the basin. Industries in and adjacent to the basin include the manufacture and processing of lumber and wood products, food and kindred products, clay products, apparel, furniture, machinery, and printing and publishing. Sand, gravel, and clay are available throughout the area, principally from beds in the Tangipahoa River. The Tangipahoa River Basin is traversed by an excellent system -of Federal, state, and local roads, and by mainline and spur railroads. Access to the river from the heavily populated area of New Orleans and vicinity has been greatly increased by the construction of the Lake Pontchartrain Toll Causeway. The initial two-lane structure was opened to traffic in 1957. An additional two-lane stiucture was completed in 1969. Further improvement in access to the Tangipahoa River area will be provided when that part of Interstate Highway 12, now under construction between Baton Rouge and Covington, is completed. Commercial air service is available at New Orleans and Baton Rouge. Smaller airfields are located at Hammond and Covington. Tangipahoa River, La. Environmental Statement The drainage area varies in elevation from about 200 feet m.s.l. in the headwaters to near mean sea level in the marshlands adjacent to the river at the lake. The width of the stream varies from a few feet in the upper reaches to about 200 feet near its mouth. The channel is very tortuous throughout its length. Streamflow is fairly rapid in the upper reaches but becomes tidal in the lowlands adjacent to the lake. River stages vary from 3 to 20 feet in the upper reaches and from 2 to 5 feet or more in the lower reaches from freshets. Stages in the lower reaches of the river also vary as a result of winds and tides on Lake Pontchartrain. The flood plain varies from a few hundred feet at the head of the river to an average width of about 1 mile in the lower reaches. It is relatively flat in cross section and is laced with numerous old channels and small streams. Beyond the bottomlands, which are composed mostly of woodlands, the landside rises abruptly to the adjoining hills. A fringe band of fresh water marshes is found at the mouth of the river between the bottomlands and Lake Pontchartrain. Native vegetation of the flood plains generally consists of second growth mixed hardwoods. The overstory of the bottomlands and hillsides varies in makeup but includes oaks (numerous species) , sweetgum, beech, tupelo gum, magnolia, hickory, maple, tulip poplar, cypress, sycamore, ash, cottonwood, and pine. Primarily the understory of the same area consists of starbrush, buttonbush, ironwood, willow, holly, redbud, dogwood, sumac, and gallberry. From the mixed hardwood bottomland habitat, the vegetation composition graduates into a hardwood-pine association and upon reaching the hilltop a pure pine or pine-hardwood climax is dominant. Typical vegetation in the fresh water marshes is maiden cane, water pennywort, water hyacinth, pickerelweed, alligatorweed, and bulltor.gue. The forest,marsh and water areas provide varied and highly productive habitat for game and furbearing animals and waterfowl. Game animals and fowl occurring in the study area include deer, rabbits, squirrel, turkey, woodcock, rails, snipe, ducks, and gallinules. Upland game associated with the agricultural and forest lands consists of quail and doves. Principal furbearing animals are mink, otter, raccoon, and opossum. Tangipahoa River has a high fishery value and outstanding aes­ thetic characteristics in its present natural state. This stream possesses scenic beauty, fast flowing, clear, productive water that offers unique recreational opportunity. Because of the natural attributes possessed by this river, it has been designated as a "natural and scenic river" under the Louisiana Natural and Scenic River System. It is one of the few streams in Louisiana that has water of a sufficient quality to produce and support high populations of Kentucky bass. Other game fish found in the river are black bass, white and black crappie, catfish, and numerous species of Tangipahoa River, La. Environmental Statement sunfish. Crabbing is also a popular sport in the zone of tidal influx. The river above La. Highway 22 is a praised "float-fishing" stream and is utilized by local residents as well as by sports fishermen from neighboring parishes. Because of its numerous picturesque sandbars and clean water, the upper reaches of the river are utilized for swimming, sunbathing, and picnicking at the various access points and road crossings. Below La. Highway 22 the Tangipahoa River is of sufficient size to accommodate larger inboard and outboard boats (up to 20-25 feet in length). Recreational activities include fishing, hunting, waterskiing, swimming, and boating for pleasure. Lake Pontchartrain is a 640-square mile coastal estuary lake surrounded by urban development, marshes, and swamps. It offers a variety of recreational opportunities in the form of fishing, hunting, boating, waterskiing, swimming, sailing, picnicking, and camping. Commercial fishing and trapping activities are closely related to the lake, swamp, and marsh areas. Dredging of the shell reefs for road construction material is an important resource of the lake. All these resources are readily available to the metropolitan area of New Orleans. Many boats are operated on the lower Tangipahoa River from La. Highway 22 (mile 15.5) to the lake. Most of these boats are transported to the river on trailers and are usually launched from the bank.