Stormwater Monitoring Analyses at Caltest Labs

Stormwater Monitoring Analyses is required by EPA and States. Rain water under regulation is sometimes referred to as run-off, as in urban runoff, industrial run-off, or agricultural run-off. Rain itself may contain trace pollutants, but the focus of stormwater monitoring is on pollutants scoured, rinsed or otherwise mobilized by rain.

Since the overwhelming success of the Clean Water Act implementation improving surface water pollution related to point source discharges from sewage treatment plants and industrial sources, the largest source of pollutants to waterways now come from rain run-off. Rain water mobilizes pollutants it comes in contact with. This type of pollution transport is everywhere rain falls on sources of pollution. This contribution of pollutants to waterways is called a ‘Non-Point Source’.

A point source of pollution is associated with an ‘end of pipe’. Think of a wastewater treatment plant that takes in water from sanitary sewers, cleans it up and discharges it to the environment – that is a point source, a known fixed point. Stormwater enters waterways from a large number of directions and points too numerous to consider in the straight-forward way we think of an end of pipe source. Stormwater comes in contact with, and transports sediments, pesticides, trace levels of metals, bacteria, oils, trash etc. Stormwater pollution varies with the sources of pollutants present from urban sources to agricultural to timber harvesting and mining related.

Stormwater/non point sources of pollution are the largest cause of impairment to waterways of the U.S. and are now under regulation. Some of the monitoring (depending on the area of land involved, and the use of the land) is regulated under general permits (general construction permit, general linear construction permit, general industrial permit, general municipal permit), and some permits specific to a large municipal area.

The U.S. Environmental Protection Agency (EPA) administers the Clean Water Act. Within the Clean Water Act is a system of regulating discharges of pollution to waterways called the National Pollutant Discharge Elimination System. The common acronym for this permit system, and the permit itself for the permit holder is NPDES. The NPDES permit is the regulatory tool used by the EPA, and or the State (when the state applies EPA programs) to require management of a water discharge to limit pollution to the public waterways. In the case of stormwater, much of the management is application of best practices to try and not let sources of pollution get rained on, or prevent the rain from transporting pollutants all the way to the public waterway.

In this sense much of stormwater management does not involve direct monitoring with analytical chemistry and microbiological methods, but rather oversight of best management practices. Stormwater permits may include covering soil piles to avoid mud flows and using straw to slow down and filter highly turbid muddy water going down a storm drain. It would also include things like street sweeping to try to physically remove urban pollutants from streets prior to rain rinsing them into the storm drains. Much of stormwater regulations are actually pollution prevention programs, attempting to prevent the mobilization of pollutants into waterways. Some of the stormwater regulations do include treatment of sorts, such as detention basins where some pollutants settle out before entering streams, or vegetated swales where some pollutants are trapped by the soil and plants etc. Whatever the practices employed to improve the quality of stormwater with respect to pollutants, at some point the water itself may be tested to document its quality. That is where Caltest Analytical Laboratory, and labs like it come into play.

Caltest provides analyses of stormwaters for compliance monitoring. Stormwater analyses are related to the Clean Water Act, which requires analytical methods listed in the Federal Register (40 CFR part 136). Caltest is certified for the use of these required methods. Some of the pollutants of concern for stormwater include sediments, metals (like mercury, copper, lead and zinc), pesticides (like diazinon, chlorpyrifos, and pyrethroids), petroleum hydrocarbons (fuels and oils), nutrients (like phosphorus and nitrogen), bacteria, and oxygen demand.

Caltest provides appropriate containers for stormwater samples along with chain of custody forms, and instructions related to EPA recommended preservatives and holding times (how soon the sample must be analyzed after sample collection).

What gets measured? The permits themselves will dictate the minimum monitoring parameters, and may call for additional tests when you know you have an opportunity for pollution related to the land use. Typical tests include:

Some additional testing related to specific problems in a watershed might include:

Caltest provides couriers to come pick up your samples, or can receive samples from your shippers such as UPS etc. We recommend that you coordinate with the lab so that analyses can begin within the specified holding time requirements.

To discuss your permit monitoring compliance needs contact one of our project managers at Caltest Analytical Laboratory.

Send us an email at for further information.

Caltest provides NPDES (National Pollutant Discharge Elimination System) compliance testing & analysis of wastewater, surface waters, stormwater,
pyrethroid pesticides, and methyl mercury analysis by EPA methods optimized for low levels of reporting.