Revenue for the month reached $1.1m (£818,248/€950,620), down 21.4% from August last year and the lowest amount since $351,425 in July last year.
The August total was also down 66.7% from $3.3m in July of this year.
Mobile revenue for the month amounted to $723,453, while retail revenue was $406,406, with $262,499 at the Tiverton Casino and $143,907 at the Twin River site.
Players wagered a total of $24.0m on sports in August, up 3.9% from $23.1m in the same month last year and also 8.6% higher than $22.1m in July this year.