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Those who braved the soggy weather while tailgating before the Boise State-San Diego State game probably didn’t give a second thought to how well the Snapdragon Stadium site manages stormwater these days. But the truth is, the property handles rain way better than it used to. When SDSU took over the 166-acre spot in Mission Valley back in 2020, the main focus was building Snapdragon Stadium at the northwest corner. While the new stadium was going up, the old stadium smack in the middle was being torn down. They used debris from the demolition and tons of fill dirt to raise the ground level by at least 10 feet, solving decades-long flooding problems that had plagued the area.
A memorable example of past flooding happened about 15 years ago during the Poinsettia Bowl between SDSU and Navy. The Qualcomm Stadium parking lot and even the field itself were flooded just a day before kickoff. They had to bring in pumps from Riverside County to drain the water, which was jokingly nicknamed Lake Murphy. Still, the field was playable by game time, and SDSU clinched their first Division I bowl win, 35-14. Since then, SDSU hasn’t just raised the site’s surface; they also upgraded the drainage systems, especially on the east side where they’re planning 4,600 residential units.
For years, the old stadium was surrounded by nearly 19,000 asphalt parking spots. When it rained, water ran off those paved areas, picking up bacteria, chemicals, and other nasty stuff, washing it straight into the San Diego River. Thankfully, that huge lot was replaced by 80 acres of open space, including parks and landscaped areas along the southern and eastern edges. Locals have dubbed this green stretch “The Green Sponge” because the soil and plants naturally absorb and filter potential pollutants before the water reaches the river.
Water from other parts of the property is captured and sent through a network of pipes leading to bioretention basins and engineered wetlands. You can spot these basins south of the trolley station and near the southwest corner of the site. They’re built above the 100-year floodway with special soil, native plants, and an impervious liner that keeps groundwater safe. The filtered water then exits through perforated pipes. Engineered wetlands are found south of Snapdragon Stadium and on the northeast and southeast sides. These in-ground concrete structures filled with sand and clay act as natural filters for pollutants.
Contamination problems here go way back—about 40 years ago, leaks were found at the Mission Valley Terminal fuel storage tanks close to the northeast edge of the site. Petroleum had leaked under the parking lot and the old stadium itself. Cleanup started two decades ago and involved removing almost two million pounds of contaminants. The San Diego Regional Water Quality Control Board declared the soil and water clean of petroleum contamination three years ago.
More recently, SDSU announced it received a $2 million grant from the San Diego River Conservancy to build a River Park laboratory dedicated to training and research, strengthening efforts to keep the area environmentally healthy. Overall, the transformation of the old stadium site into Snapdragon Stadium and the surrounding green spaces represents a big step forward in sustainable urban development and stormwater management in Mission Valley.
