Crosstalk between SDA and SCL is the worst. They are not two signals to go through a cable, they are both independent weak logic signals. Never put them next to each other.
See my Wiki at Github, and look for the "page 60" in bold.
There are three kinds of people: Those who do not know page 60, those who do but deliberately ignore it, and those who do and understand it. The last group is the smallest.
Do you mean twisted pair of SDA + GND and an other twisted pair for SCL + GND. Is that GND wire carrying any current ? Are you sure ? The I2C bus is weak, it is not meant to travel outside a pcb board and it is not meant for a noisy environment. Is there a LCD display at the end ? Then you have a lot more problems with electrical noise captured by the high-impedance internal circuit of the LCD.