Here is your short paragraph on Ganga-Dashahara:
In the month of Jyestha (May/June), the tenth day is called ‘Ganga- Dashahara’. It marks that ancient time when the Ganges, led by Bhagiratha, reached the plains of India at Hardwar.
Ganga Dashahara means that it ‘destroys ten’ life times of sins. Throughout the first ten days of the fortnight and climaxing on the tenth, devotees bathe by the thousands at Dashashvamedha Ghat and it is said that bathing here on all ten days destroys the sins of ten life times.
On the tenth day, some of the most enthusiastic of worshippers will cross the river in boats trailing long garlands of flowers to decorate the goddess-waters. In former day, this was also a time of great swimming competitions, when athletes young and old would swim across the river and back.