Northern Lake Service (NLS), Inc. We have been a trusted source for environmental and analytical laboratory services for over 37 years. Our commitment to providing the highest quality data to our customers coupled with a dedication to providing superior customer service and support make us the first choice when it comes to your environmental testing needs. We routinely provide analysis for drinking water, wastewater, groundwater, soil, sludge and other matrices for a variety of markets including municipal, industrial, tribal, federal agencies and many others.