location	turbidity
a	1.0
a	1.2
a	1.1
a	1.1
a	2.4
a	2.2
a	2.6
a	4.1
a	5.0
a	10.0
b	4.0
b	4.1
b	4.2
b	4.1
b	5.1
b	4.5
b	5.0
b	15.2
b	10.0
b	20.0
c	1.1
c	1.1
c	1.2
c	1.6
c	2.2
c	3.0
c	4.0
c	10.5