Record low rainfalls will have ships paying more to transit the Panama Canal.

The Panama Canal Authority (ACP) will charge a freshwater surcharge on vessels over 125 feet in length that includes a fixed fee of $10,000 per transit and a variable fee ranging from 1% to 10% of the vessel's tow, depending on the water levels of Gatun Lake at the time of transit.

The lake is the canal's primary source of water, and 2019's rainfall totals were the fifth lowest in the last 70 years, exacerbated by an increase in water evaporation due to rising temperatures.

The canal will also adjust the number of reservation slots to 27 and require ships to pay its booking fee in full within two days, ACP said.

Ships that are at least 91 feet wide will also have to pay a $5,000 vessel visit creation fee, while those longer than 125 feet but narrower than 91 feet must fork over $1,5000.

"Together, the new measures will allow the Panama Canal to better anticipate the number and type of ships transiting the waterway, and therefore allocate water resources accordingly," ACP said in a statement.

The number of oceangoing commercial ships crossing the canal has grown from 11,992 in 2017 to 12,281 in 2019.

The waterway was widened in a project that finished in 2016 in an effort to double capacity.

Throughout 2019, the canal authority cut draft limits several times due to the water levels in Gatun Lake.