Date Established: 1875
Date Ceased Operations: 2003
Annual Production Graph
Average Production (Annual Tons): 33,331
Best Production Year: 1961/73,554 Tons
Family Ownership: Vadi, Amell-Massó, Cabrera, Bianchi
Corporate Ownership: Sucrerie Central Coloso, Western Porto Rico Sugar Co.
Coloso , then only an Ingenio or "trapiche", was established in 1827 as Hacienda Caño Las Nasas by Luis de Medina.  In 1864 it was an oxen driven "trapiche" producing approximately 100 "bocoyes" or hogsheads of muscovado sugar.  It was later owned by Corsican immigrant Angel Luis Santoni who installed a steam driven mill.  In 1871 it was owned by Corsican immigrant Emilio Vadi Bonelli who appears to have been related to Santoni as the mother of his children was Rosario Santoni.  Vadi changed the name from Hacienda Caño Las Nasas to Coloso and installed a larger mill acquired in Glasgow.  By 1875 it was considered a "Central" producing 1,000 bocoyes of muscovado sugar with production increasing up to 3,000 barrells. 
In 1895 it was shut down due to financial difficulties and in 1897 was acquired by José Amell Massó, a Catalonian immigrant who in 1902 annexed the lands and facilities of his Central Monserrate just about 2 Km from Coloso on the banks of the Culebrinas River North of the Cañas River.  
The French group that under the name Sucrerie Central Coloso acquired the sugar mill from Amell Massó in 1904 was headed by the new Credit Mobilier of Paris (not the original Credit Mobilier ) and secured as Director M. Henri Dechuy, an engineer who had drawn attention in the sugar world at the time for his remarkable work on losses by entrainment in evaporators.  In 1916 Mateo Fajardo Cardona, owner of Central Eureka , sued Sucrerie Central Coloso in Federal Court claiming damages related to the sugar mill's sale in 1904 trying to prevent its upcoming sale to Sucrs. de Bianchi.  Fajardo was unsuccesfull and the Bianchi family together with Carlos and Guillermo Cabrera took over Coloso in 1916. 
By early 1921, Coloso, then operating as the Western Porto Rico Sugar Co. owned by the Cabrera and Bianchi families, was in receivership due to $57,000 in unpaid debt to the Mercantile Bank of the Americas.  General Receivers were Moses A. Walker, one of the major stockholders in Pasto Viejo Sugar Co. of Humacao and in 1926 instrumental in the creation of the United Puerto Rican Sugar Co. and Rafael Martinez Dominguez, administrator of Yabucoa Sugar Co.   Eventually financial difficulties were overcome and Coloso continued to be a major sugar mill.
Based on average lifetime production, it was the 5th largest sugar mill in Puerto Rico, and the 2nd largest locally owned behind Mercedita.  This sugar mill's production graph is a typical pyramid shape; continuous increase until 1961 and continuous decline thereafter. 
The government owned Puerto Rico Sugar Corporation leased Coloso 1972 and the Puerto Rico Land Authority acquired it in 1976.  It was run by the government until 2002 when it was the last operating sugar mill in Puerto Rico.
As stated on the banner in the weigh station picture, the local municipal government and the Government of Puerto Rico have joint plans to establish a more modern sugar mill at this location.  The purpose is to process sugarcane harvested nearby for the production of molasses for Bacardi Corp.  During our visit in July 2014, we did not see any activity indicating these plans are on their way except that sugarcane seeds have been planted across PR-2.
When we visited Coloso it was raining, hence the gray sky on the first picture. The blue skies were the following morning!