Our Palo Alto Creek Monitoring Program Celebrates its Third Birthday

By Erin Banks Rusby, Project Manager

“And now, the moment of truth… Will we see water at Terman today?!” How frequently this question has crossed my mind in the past three years as we prepared to visit Adobe Creek at Terman Middle School in Palo Alto, one of our most notoriously dry locations for water quality monitoring. 

Ever since we began our Palo Alto water quality monitoring program in December of 2013--right in the middle of the drought-ridden, sun-soaked winter--we have played this guessing game. This winter, one of the wettest in recent memory, the answer was yes! We seemed to have turned a corner on the long-needed rain. But drought or no drought, our monthly Palo Alto water quality monitoring program will continue to be an informative snapshot of the state of our creeks.

Our monthly creek monitoring program is a partnership with the City of Palo Alto. The City first launched the program in 2002, after the first rain of the season resulted in a precipitous and prolonged drop in the dissolved oxygen levels that led to the death of at least 90 striped bass and five bat rays in the Palo Alto Flood Basin. The first rain of the season, or “first flush,” often causes a decrease in dissolved oxygen levels in the water as runoff (such as lawn fertilizers and pet waste), washes into storm drains and enters the creek without treatment. Fish and other aquatic organisms need oxygen in the water just like land-based critters need oxygen in the atmosphere, and cannot withstand more than a few days with depleted levels. 

Public outcry yielded the creation of a citizen’s water quality monitoring program led by the City of Palo Alto to get volunteers out collecting water quality data. The City awarded Grassroots Ecology the contract to do water quality monitoring in 2013 (at the time, we were called the Acterra Stewardship program). Since then we have been working at Palo Alto creek sites to educate community members about what they can do to prevent creek pollution and understand the trends in each watershed.

For our regular volunteers, the past three years have been an eye opening experience, exposing the changes in local creeks over time. “One [can] really get an understanding of the changes in the seasons, not only the water levels but the vegetation and creek ecosystem,” says Kit Gordon, Los Altos Hills resident and long-time volunteer. “The sight, sounds, and smells of each location change throughout the year.” In addition to collecting physical and chemical data, volunteers take photos each month to document the look of each creek site.

(Left to right) Bob Foglesong and Ann Knopf record data and assist with observations as Kit Gordon lowers the meter into Adobe Creek on the Foothill College campus.

Involving volunteers on a regular basis is at the heart of citizen science efforts. Having more regular observers on our creeks allows us more opportunities to alert the city if something seems abnormal. “It’s like going to visit a member of the family,” says Paul Gardner, a regular volunteer on Adobe Creek. “You want to know they are in good health, running clean, teeming with life.”If anomalies occur (such as abnormally low dissolved oxygen levels), we can report them to the City to ask for additional testing and follow-up.

Sometimes, all it takes is looking at a creek to see that something is wrong. In the winter of 2014, we visited a long-time monitoring site along Matadero Creek at Old Page Mill Road. Claire Elliott, Senior Ecologist and Associate Director of Grassroots Ecology, noticed an oily sheen spread out over much of the surface of the languid water. She contacted the City of Palo Alto, who contacted Stanford University, where this portion of the creek is located. With a little excavation, Stanford officials were able to locate the source of the oil- a site just upstream of our monitoring site where someone had been illegally dumping near the creek, probably several decades ago. The oil was just now reaching the creek. Thanks to Claire’s observation and action, Stanford was able to hire a crew to contain the oil and remove it from the affected embankment, minimizing harm downstream.

Water runs clear at Matadero Creek at Old Page Mill Road, November of 2014 where a small oil leak was discovered during the winter of 2013-2014. Photo Credit: Bob Foglesong.

Water quality monitoring requires a few instruments, volunteer help, and a long-term view of our creeks- their past, present, and potential future. Why do we witness certain trends and what can those trends tell us about the history and future of the creek in question? Below is a synopsis of trends we have observed in San Francisquito, Barron, Matadero, and Adobe Creeks in Palo Alto over the past three years.

Palo Alto water quality monitoring site map.

Water Presence: As our readers might have surmised, the dearth of rainfall during the drought resulted in us observing water less frequently, and at fewer of our monitoring sites. For example, while conducting monthly monitoring between December 2013 and December 2016 at our Terman Middle School monitoring site for Adobe Creek, we only observed water five times, and only if it had rained within the previous 24 hours. With all of the rain this winter, we have now been able to observe water at that site two months in a row, even if it has not rained recently. It remains to be seen if this trend will continue; our local creeks are seasonal to a large extent, and it is natural to witness a drying back of the creek. 

Water Temperature tends to drop in the fall and winter as the influx of rainwater cools creeks. Temperatures tend to rise over the summer as air temperatures rise and there is no fresh rain water flowing into the creek.

Dissolved Oxygen varies seasonally as well. With the first rains, oxygen levels tend to drop. Oxygen levels tend to look the best during our winter months, when sustained flows are fed by rain storms. Oxygen levels tend to decrease across sites over the summer as the rate of water flow slows and favors algae formation. Though algae are photosynthetic and produce oxygen, the organisms that decompose dead algae consume oxygen, ultimately causing oxygen levels to decrease.

pH: Known as potential of hydrogen, pH is a measurement of the acidity or basicity of a liquid. The pH of a liquid can range from 0 to 14, with the ideal pH for bodies of freshwater falling within 5.5-8.5. The pH of our Palo Alto Creeks varies from creek to creek, and does not vary much seasonally. The biggest factor determining pH? Think geology. Seismic activity has shaped the composition of the rocks all along the Peninsula. The rocks these creeks flow over will have a large effect on the pH (consider the basicity of limestone) and could also explain the variation we observe between creeks that are close together, even in the same watershed.

By forming a baseline of water quality measures at different local creek sites over time and in various circumstances, we are determining what “normal” looks for each individual creek. As our climate continues to change, exacerbating drought length and intensity, these data will help us understand and anticipate threats to water quality, and take action accordingly. It will be an important tool for all the stewards yet to come.

Interested in monthly creek monitoring? Contact erin@grassrootsecology.org

Matadero and Barron Creeks: Third Thursday or Friday of each month
Adobe Creek: Third Friday morning of each month
San Francisquito Creek: Generally, third Saturday of each month