Atmospheric River... What can you do?

Updated: Mar 31

We have been experiencing some unusually heavy rain this year. With inches of rain still predicted in the forecast, what are some things your site can be doing to reduce it's impact?

On some of our sites we've seen several inches of rain collected in a short period, this phenomena can be explained by an intense burst of rain brought in by an Atmospheric River. An Atmospheric River (also known as a Pineapple Express in our region) is a storm system that can hold as much water vapor as the mouth of the Mississippi River ( When this system hits land it can release it's water in vast quantities, drenching the areas below and near it.


Fortunately for the snow-pack depleted state, there is more rain in sight. NOAA just released an announcement stating that the El Nino has officially landed ( It's going to be relatively weak in comparison to previous El Nino's; however, it's important that we take this seriously and work to prevent this rain from picking up pollutants.

As Stormwater Managers, we work with you to help keep your site from polluting surrounding waterways. It can be stressful to ensure that your site is in compliance with all required environmental and stormwater permits, and we want to help you prevent as much pollution as you can. When there are several inches of rain in a short period of time, it can show all of your weak spots on the site. It's really important to address these issues in advance proactively.

The EPA predicts stormwater to be responsible for 90% of pollution in our waterways. That’s why we help our clients manage stormwater runoff, and make sure that whatever water is leaving their site is clean and ready to enter a waterway.

Here's a list of things you can do to help prevent your site from getting an exceedance during these heavy rains...

Stop Working

When there are inches of rain coming for your site, it's important to stop working for both safety and pollution prevention. Pouring concrete, grading, or even just accessing muddy sites during rain can cause pH and turbidity discharges. Use NOAA's weather tools to keep track of the weather >

Prevent pH and Turbidity Exceedances

This can be more difficult that it seems. In general keep things covered, properly stored, and stop working on the site before/during/immediately after the rain event. Here are some other resources we have on how to keep your site in tip top shape >

Utilize Your QSP

Have your Qualified SWPPP Practitioner review your site, and make sure that BMPs are properly installed. Maintaining good communication with your QSP during heavy rains is critical for ensuring site preparedness. Implement the corrective action recommendations within 72 hours and before more rain. If the site warrants major BMP changes, also consult with a QSD. We are here to help you, call us at (707) 693-1926 with questions.

Implement Erosion Control

The best way to keep dirt onsite is with adequate erosion control. Even on flat and contained sites where erosion control is not typically foreseen, in these extreme rain events we have seen the need for extra protection due to flooding and saturated conditions. Our team can help you decide where/what to place along your site for maximum benefit. The Construction General Permit requires an effective combination of erosion and sediment control, not just sediment control (e.g. fiber roll, silt fence, inlet protection, etc.).

Control Turbidity at the Source

Find areas that would trigger high turbidity readings. Such things to consider would be disturbed areas with open soil and uncovered stockpiles adjacent to waterways or storm drain inlets.


More rain is to come, please consider this when you plan on disturbing soil or starting more work. It's a disaster waiting to happen. Keep the soil where it needs to be, and work around the rain. Winter is a really tough time for construction because the risk is real and very high for exposure. We can't stress this enough. Proper scheduling means avoiding grading, trenching, excavation, paving, concrete paving and other pollutant generating activities during the rainy season.

Stabilize All Areas

All of this Stormwater runoff can mean big trouble for erosion control (as stated above). Try your best to stabilize all areas under threat. This could be with the appropriate blanket, plastic (avoid if you can), rock stabilization, hydraulic mulch, hydroseeding, landscaping or other re-vegetation (this takes time), and emergency soil binder (look at requirements).

Beef Up Sediment Controls

Lots of sediment is being moved around by this Atmospheric River. Keep sediment on your site with silt fences, fiber rolls, and other necessary BMPS. Sediment is the #1 pollutant in US waterways. We are here to help! Call us at (707) 693-1926 if you need some help with your BMPs.

Avoid Driving On Your Site

Excessive driving in the mud and flood waters often results in turbidity exceedances. This can occur when mud is tracked out onto pavement near inlets or stirs up turbidity in the runoff that then leaves the site. Discourage subcontractors and employees from driving on site. In addition, avoid deliveries made to your site.

Ready Rock Entrances

One big opportunity to reduce sediment from leaving your site is through implementing a strong rock entrance. Follow guidelines on proper installation to provide stabilization to the entrance. Tell employees and subcontractors to restrict access to rocked, graveled and paved areas only during rainy and muddy conditions. If you drive on the mud and then over the construction entrance, this can be costly as it can choke up rock with mud and thus require maintenance or worse, more rock which is expensive.

Avoid Damaging Existing BMPs

Focus on leaving existing BMPs where they are, and prevent damaging them. Use what you got and make sure your Stormwater soldiers AKA gravel bags, fiber rolls, and silt fences are left to do their job. Maintain them as needed. Especially avoid driving over any erosion control which during rain can totally destroy it.

It's a stressful time during the year. Know that we want to help you do your best to protect the environment and avoid fines. It's our goal to do the best we can to help you. Do not hesitate to call us for help, and whenever possible prevent the problem as much as you can before it's too late.

For many, these rains were not expected to be so strong. This winter has proved itself to be a challenge. Keep in communication with us, and be ready to sit back for a couple more months.

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