Revise and Edit Script

Today I had to revise the script since it is due on Monday. I added some citations and came upon new information. Some new information included the health concerns of the Tijuana River. Apparently the Tijuana River is very polluted one can get diseases such as cholera, hepatitis A, and malaria. Sounds severe. http://www.american.edu/ted/TIJUANA.HTM. The source is probably reliable since the format is proffessional. The Tijuana River is definately in worse condition than the San Diego River. But I wonder why? Could it be because there is no one to guard the river from pollution, in Tijuana? I cannot make any assumptions because I am not that well informaed about this. Also, I could not find any information on how one can get malaria from just getting near the river? I always thought you get that from mosquitos not from just physical contact with the water. If anyone knows the answer to that question feel free to answer.