Sounds about right, er left.     What you're doing is going up, over, and around the "tip" of the lake.  Hence all the left turns - assuming that seemed odd to you.

Anyone who has been to Cascade Launch in Moses Lake, are these directions right? They are from Map Quest

Cascade Launch:
Take the I-90-BL / WA-171 N exit- EXIT 176- toward MOSES LAKE.
0.2 miles
Turn LEFT onto I-90 BL / WA-171 / W BROADWAY AVE.  2.9 miles
Turn LEFT onto N ALDER ST / STRATFORD DR. Continue to follow STRATFORD DR.    0.4 miles
Turn LEFT onto W VALLEY RD. 1.7 miles
End at 2001 Valley Rd W
Moses Lake, WA 98837-9654, US

Thanks,
Stu