A mass in Vietnamese is also offered every other week. St. Mary's of the Assumption Parish is the largest Catholic parish in Lawrence by Mass attendance and number of registered parishioners. It has the largest multi-lingual congregation in the city and has been offering Spanish masses since the early 1990s. Since the 1990s, increasing numbers of former Catholic churches, closed since the 1980s when their Irish or Italian congregations died out, have been bought by Hispanic evangelical churches. The 2000 Census revealed the following population breakdown, illustrating the shift toward newer immigrant groups:  Dominican Republic, 22%; other Hispanic or Latino, 12%; Irish, 7%; Italian, 7%, French (except Basque), 5%; Black or African American, 5%; French Canadian, 5%; English, 3%; Arab, 2%; German, 2%; Lebanese, 2%; Central American, 1%; Polish, 1%; Portuguese, 1%; Guatemalan, 1%; Vietnamese, 1%; South American, 1%; Spanish, 1%; Cambodian, 1%; Scottish, 1%; Cuban, 1%; Scotch-Irish, 1%; Ecuadoran, 1%. According to the United States Census Bureau, the city has a total area of , of which is land and (6.07%) is water. Lawrence is on both sides of the Merrimack River, approximately upstream from the Atlantic Ocean. On the north side of the river, it is surrounded by Methuen. On the south side of the river, the town is bordered by North Andover to the east, and Andover to the south and southwest. Lawrence is approximately north-northwest of Boston and southeast of Manchester, New Hampshire. Aside from the Merrimack River, other water features include the Spicket River, which flows into the Merrimack from Methuen, and the Shawsheen River, which forms the southeastern border of the city. Lawrence has two power canals that were formerly used to provide hydropower to the mills - one on the north bank of the river, the other on the south. Channeling water into these canals is the Great Stone Dam, which lies across the entire Merrimack and was, at the time of its construction in the 1840s, the largest dam in the world. The highest point in Lawrence is the top of Tower Hill in the northwest corner of the city, rising approximately above sea level. Other prominent hills include Prospect Hill, in the northeast corner of the city, and Mount Vernon, along the southern edge of the city.