Outfall System

stormwater treatment controls


A series of outfalls on the beach adjacent to Scripps Institution of Oceanography discharge seawater back to the ocean. Because the ocean adjacent to Scripps Institution of Oceanography has been designated as an Area of Special Biological Significance as well as a Marine Protected Area, UC San Diego takes special precautions to ensure that these outfalls do not contain pollutants.

Scripps Institution of Oceanography has maintained an open flow-through seawater system to support its research and teaching mission since 1910.  The high-quality filtered seawater is a critical resource in numerous marine biological and oceanographic research and teaching activities.  For example, having a natural seawater flow-through system allows for the full life cycle of kelp and other algae and the growth and settlement of local macroalgaes.   

The open seawater system supplies 500,000 to one million gallons per day of seawater to laboratories and aquaria. This seawater is discharged back to the ocean through outfalls described below in accordance with the conditions and provisions of a National Pollutant Discharge Elimination System (NPDES) permit issued by the San Diego Regional Water Quality Control Board. These outfalls discharge into the San Diego-Scripps Area of Special Biological Significance, located just north of the San Diego-La Jolla Ecological Reserve.

The outfalls are located as follows: 

Outfall 1

Water falling from a concrete structure built into a slope.

Outfall 1 is located approximately 500 feet north of Ellen Browning Scripps Memorial Pier and discharges approximately 400,000 to 700,000 gallons per day of filtered seawater that has circulated through the Birch Aquarium at Scripps, Hubbs Hall research aquaria, the Marine Conservation and Technology Facility, and NOAA Southwest Fisheries Science Center aquaria. Outfall 1 also discharges stormwater during rain.

Outfall 2

White pipe protruding from embankment above beach sand.

Outfall 2 is a stormwater outfall located approximately 240 feet south of Ellen Browning Scripps Memorial Pier, immediately downstream of two urban runoff filter treatment systems. This outfall discharges storm water only. Flow from this outfall is based on storm conditions.

Outfall 3

Water pours from pipe protruding from wall underneath Scripps Pier.

Outfall 3 is located underneath Ellen Browning Scripps Memorial Pier and discharges approximately 50,000 to 220,000 gallons per day of filtered seawater from the Experimental Aquarium and intermittent discharges from three seawater storage tanks when a tank is drained for maintenance (approximately once or twice a year per tank).  

Outfall 4A

Four slots in concrete wall on slope above beach.

Outfall 4A is comprised of two separate pipe outlets located approximately 40 and 75 feet south of Scripps Pier, underneath a deck area. Outfall 4A intermittently discharges between 3,000 to 30,000 gallons of intake seawater several times a year when the settling tanks overflow or are drained for maintenance. The intake seawater is pre-treated through a sand and debris drum filter system located on the pier.   

Outfall 4B

Grey pipe attached to wall above beach and below industrial filter mechanism.

Outfall 4B is located approximately 25 feet south of Scripps Pier and north of Outfall 4A. This outfall discharges between 100 to 20,000 gallons per day of back-flushed seawater from the sand filtration system. The system filters seawater pumped from the end of the Scripps Pier and is backflushed when pressure in the system exceeds the set safety threshold. The discharges are intermittent depending on ocean conditions and the water quality of the incoming seawater.  For example, the filters are backflushed more frequently during storms and when there are algae blooms.   

Scripps Institution of Oceanography is committed to meeting clean water standards to protect the beneficial uses of the San Diego-Scripps Area of Special Biological Significance and to comply with the conditions of the NPDES permit. Seawater that is used in aquaria that contain non-indigenous species or genetically modified organisms is treated prior to discharge. These treatment systems consist of a combination of filtration, ultraviolet sterilization, and, in most cases, ozone disinfection.  If a medication is used in an aquarium to treat an animal or a chemical is added to the seawater, the seawater from that system is discharged to the sanitary sewer system in accordance with City requirements.  The seawater that is discharged onto the beach does not contain any chemicals.  

Water quality monitoring is performed twice a year on the seawater and stormwater that is discharged from these permitted outfalls, once during dry weather and once during wet weather, to ensure the water quality standards in the California Ocean Plan are being met.  In addition, benthic marine studies are performed to verify that the discharged seawater and stormwater does not adversely impact the biological communities in the ASBS or compromise protection of ocean waters for beneficial uses.  

To improve the water quality of urban runoff from Scripps Institution of Oceanography, the following source and site controls have been implemented:

  • Four innovative urban runoff biofilters have been installed above the seawall to treat urban runoff and prevent pollutants from reaching the beach.
  • Erosion and sediment controls have been installed on the slopes at Scripps Institution of Oceanography.
  • Outdoor material storage areas are designed to prevent storm water pollution.
  • Source control best management practices are implemented when performing outdoor work activities to prevent pollution.

More information on UC San Diego’s Storm Water Management Program can be found at stormwater.ucsd.edu.

Questions about the UC San Diego outfall system can be directed to Kimberly O’Connell with Environment, Health and Safety at koconnell@ucsd.edu