Abstract: Lajas Valley is plagued with problems of salinity and waterlogging the soils. Use of brackish (500 milligrams per liter) irrigation compounded ground water for the problem until an irrigation-drainage system was constructed in 1955. Lajas is an alluvium-filled limestone highlands. The alluvium, mostly clay and as much 300 feet (90 meters) thick, contains brackish ground water except in the recharge areas located along the foothills...Results from a digital model show that a network of discharge wells could alleviate waterlogging of the soils in the artesian area.

Report containing an aeroradioactivity survey of Puerto Rico made on behalf of the Division of Biology and Medicine, United States Atomic Energy Commission. Topics include the types of bedrock noted in the area as well as their levels of radioactivity.

Map with graded color shading to show levels of naturally-occurring gamma aeroradioactivity within Puerto Rico. Details about the survey and map creation are printed at right. Scale 1:250,000.

Abstract: The principal chemical, physical and biological characteristics, as well as the hydrology of Laguna Tortuguero, Puerto Rico, were studied from 1974-75. The lagoon, with and area of 2.24 square kilometers and a volume of about 2.68 million cubic meters, contains about 5 percent of seawater. Drainage through a canal on the north side averages 0.64 cubic meters per second per day, flushing the lagoon about 7.5 times per year. Chloride and sodium are the principal ions in the water, ranging from 300 to 700 mg/L and 150 to 400 mg/L, respectively. Among the nutrients, nitrogen averages about 1.7 milligrams per liter, exceeding phosphorus in a weight ratio of 170:1. About 10 percent of the nitrogen and 40 percent of the phosphorus entering the lagoon is retained. The bottom sediments, with a volume of about 4.5 million cubic meters, average 0.8 and 0.014 percent nitrogen and phosphorus, respectively.