Dry Season Monitoring Protecting OC’s Waterways

Keeping Orange County’s waterways safe is a year-round job. During the dry season (May – September), our team goes out to monitor water quality at storm drain outfalls, creeks, and coastal areas. These efforts help us understand the watershed-level effects of human activity on our waterways. To learn more about watersheds, visit our What is a Watershed page.

Our team tests for a range of pollutants, including indicator bacteria (such as E. coli, Enterococcus, and fecal coliform), nutrients (typically from fertilizers), metals, pesticides, and organic compounds.  H₂OC’s monitoring efforts help keep our water bodies beautiful and surfers, swimmers, and aquatic life safe.

Let’s dive into our storm drain system and how to help keep our water bodies thriving during the dry season.

Dry Season

From May through September, rain is less likely to occur in Orange County. The storm drain system was created to move rainwater from the streets as quickly as possible to protect life and property. As a result, and unlike the sanitary sewer system, the storm drain system does not treat water. This means anything that flows into a storm drain can go untreated into our creeks, rivers, and ocean.

During dry weather, nothing should be flowing into our storm drain inlets. It’s our shared responsibility to keep pollutants out of the system to protect both our water bodies and community health. We can do this by practicing simple watershed-wise habits in our daily lives such as  picking up and properly disposing of dog waste in covered bins, following pesticide label instructions and avoiding application 48 hours before rain, and adjusting sprinklers to water only landscaped areas to prevent fertilizer runoff

Now let’s explore what we monitor, how we monitor, and where we monitor to help our waterways thrive!

Sampling Methods

Sampling is a critical part of what we do to protect our community and water bodies. To measure pollutant levels in our water bodies, we use two sampling methods – grab sampling and composite sampling. Here’s more information on each of them and their purposes:

1. Grab sampling involves collecting individual and discrete samples to measure pollutant levels at a specific point in time. This method provides a water quality snapshot for a given water body and is mainly used for our outfall and coastal monitoring programs and for specific pollutants such as bacteria.

2. Composite sampling uses an automatic sampler to collect multiple water samples over a specific time interval, usually 24-hours. This method captures fluctuations in pollutant levels over the time interval and is primarily used for mass emissions monitoring.

To support our sampling efforts, field testing equipment such as flow meters and water quality probes are tremendously helpful to get a full picture of water quality. The probes are a device that can be placed directly in the water to measure temperature, pH, dissolved oxygen, and other key characteristics.

Grab sampling and composite sampling are both important methods in providing timely, accurate data that effectively inform regulatory agencies on the best ways to keep our water bodies safe.

Storm Drain Outfall Monitoring

Storm drain outfalls are monitored to catch pollution at its source. These structures are pipes at the end of the storm drain system where the water exits into a water body.

Although storm drains are designed to move rainwater off the landscape in wet weather, groundwater and excess irrigation can flow through them during dry weather. Grab samples are collected from storm drain outfalls and analyzed for pollutants including metals, nutrients, pesticides, and bacteria. Monitoring this flow during dry weather can help identify sources of pollution.

With hundreds of storm drain outfalls across Orange County, monitoring programs are developed to adapt and prioritize specific locations. Information tracked through monitoring efforts includes a combination of the amount of water flowing though the outfall, pollutant concentrations, land uses near the storm drain, and historical pollutant trends. Observations of the outfall’s physical condition, such as presence of graffiti, litter, or overgrown vegetation are also collected and help inform municipal maintenance activities.

Inland Waterway Monitoring

Orange County’s inland waterways like creeks, rivers, and flood control channels are vital parts of our watersheds. Waterways like the Santa Ana River, Trabuco Creek, and Irvine Lake offer wonderful recreational opportunities such as running and biking trails for people to enjoy.  They also provide vital habitat for local wildlife.  

Our creeks and rivers eventually flow into our ocean, so it’s especially important to keep them healthy. One way that’s done is through mass emissions monitoring, which measures the total pollutants carried by creeks and rivers to coastal waters. Sampling locations are located within OC’s major flood control channels just before they discharge into bays, harbors, and estuaries.

Mass emissions monitoring helps our team assess water quality conditions across each watershed. At these sites, we typically collect composite samples using automatic samplers that take hourly samples over a 24-hour period to capture fluctuations in water quality during a given day. Water levels in these waterways are also monitored using equipment that supports OC’s public safety-focused ALERT system. By combining water quality and flow data, we can calculate total pollutant loads moving through the system, track long-term pollution trends, and evaluate the effectiveness of pollution prevention efforts over time.

By keeping our inland waterways healthy, we can keep our ocean healthy too.

Coastal Monitoring

Orange County’s beaches and harbors are world-famous and highly visited with places like Newport Harbor and Huntington Harbour attracting swimmers, kayakers, paddleboarders, and boaters year-round. To help keep these areas safe and healthy, H₂OC actively monitors our beaches, bays, harbors, and estuaries.

Beach water is tested weekly for indicator bacteria and the information is shared on the OC Health Care Agency’s OC Beach Info webpage to provide residents and visitors with up-to-date water quality. Bays, harbors, and estuaries can have an even larger impact on our ocean because of their sensitive habitats and potential to accumulate pollution. In addition to watershed runoff, boating and other marine activities can also contribute pollutants in these areas. For these reasons, we monitor both water and sediment quality in places like Newport Bay and Huntington Harbour.

To better understand the impacts of pollution, aquatic life within the bay sediments is also routinely monitored.  Monitoring is typically conducted on a boat, where staff collect grab samples of water and bottom sediment. Between July and September, we also monitor algae in the Upper Newport Bay Ecological Reserve, collecting algae samples from the mudflats during low-tide conditions.

By actively monitoring the water and sediment quality of our coastal water bodies, we can quickly identify issues and give residents peace of mind that their favorite beach activities are safe and coastal ecosystems are protected.

Things You Can Do to Help

You can make an impact too. If we combine our efforts, we can help our coastal and inland water bodies flourish. Common sources of pollutants include everyday residential activities, like overusing fertilizers and pesticides, not picking up dog waste, and washing cars in driveways. By keeping pollutants out of our storm drains, we can protect and preserve our creeks, rivers, and ocean.

Here are some ways to make a difference:

1. Properly Dispose of Animal Waste
   • Bring dog waste bags with you every time you walk your furry friend.
   • Pick up dog waste immediately.
   • Tie dog waste bag shut and place in a covered trash bin.
2. Reduce Potential Sources of Metals
   • Replace your worn-out brake pads with copper-free alternatives.
   • Regularly inspect your vehicle for and fix oil leaks.
   • Wash your car at a commercial car wash or on a permeable surface like your lawn instead of in your driveway.
   • Store scrap parts or other used metals indoors or under cover.
   • Use non-copper anti-fouling paint on your boat hull.
3. Prevent Littering
   • Close the lids on any open trash bins.
   • Throw away all trash in a closed bin.Place all cigarette butts in a closed receptacle.
   • Recycle and reuse materials whenever possible.
4. Minimize the Use of Pesticides
   • Use Integrated Pest Management (IPM) strategies to combat pests. IPM includes using beneficial insects, trapping (such as bait stations), weeding, and other techniques to control pests.
   • If you must apply pesticides, only do so during dry, low-wind conditions and always follow the manufacturer’s instructions.
   • Do not apply pesticides within 48 hours of a predicted rain event.

Learn more waterway-safe pest control tips here.

H₂OC’s dry weather monitoring program is a force for good to protect our neighbors and waterways. Regular monitoring more adequately informs high-level decisions about allocating resources and preventing issues before they become major problems. Thank you for helping us keep our creeks, rivers, and ocean healthy.