Friends of Sonoita Creek Volunteers conducting the RSPA assessment.

On April 12 at Cady Hall Dr. Peter Stacey, Professor of Conservation Biology at the University of New Mexico, explained the Rapid Stream Riparian Assessment (RSPA) tool. Andrew Gould, a volunteer researcher, shared the results of five years of assessment done by Friends of Sonoita Creek (FOSC) in The Nature Conservancy (TNC), Patagonia Sonoita Creek Preserve, two portions of Sonoita Creek in Patagonia Lake State Park (PLSP) and a portion of the creek on State Trust land below the Patagonia Lake Dam.

Between 2014 and 2018 there have been seven assessments by 19 volunteers covering the above four areas. The scale used is from one to five, with five being the best score given. TNC and the upper portion of PLSP have the highest score with 3.4 and 3.3 respectively. Both the lower portion of the PLSP and the area below the Patagonia Lake Dam score similarly low on the scale at around 2.7.

In arid areas like Arizona restoring riparian areas is the most productive and efficient response to the increase of CO2 in the environment, said Stacey. Riparian areas play important functions for humans, he explained. They can remove pollution, reduce flooding, provide wildlife and aquatic habitat, resist invasion by invasive plants. The
soil can create biomass which can be used for crops or forage for animals.

After eight years of collaborating with other scientists Stacey developed an effective evaluation tool that can be done quickly and does not require special equipment or training. This assessment of riparian areas is like a physical health check up, said Stacey,
and it provides an ecological basis for the health of a creek by identifying problems that need additional analyses and by identifying features that are functioning well.

The main factors that are assessed with this tool are algae and vegetation cover. The Environmental Protection Agency (EPA) measures nutrient pollution and water temperature to assess the water. If the water temperature is high, then the oxygen level is low and the stream cannot support aquatic life. Conversely, sufficient vegetation
cover results in shading, which makes a cooler stream and thus a healthier creek. Algae develops from phosphate waste of livestock or humans and are a deterrent to a healthy aquatic and wildlife habitat.

One way citizen scientists measure the health of a creek with the RSPA tool is by walking a section of the creek with a PVC tube, similar to a toilet paper roll, with crosshairs in it. The assessor looks through the center of the cross hair and answers these yes and no questions: is there algae and is there cover? “The RSPA tool is accurate because we have found that
results are repeatable,” said Gould. It is also the appropriate tool says Gould “because it looks at the whole ecological environment around the stream and not just the water in the stream. We don’t do the kind of detailed chemical analysis that is done by the Patagonia Area Water Study (PAWS) group. Our concern is with the health of all the animals and plants that depend on the stream.”

The primary threats to the health of the Sonoita Creek are trespass cattle, monsoon flooding and algae, said Gould. The Sonoita Creek above Patagonia Lake has never been protected from cattle grazing, says Gould, and both cattle and massive monsoon flooding have severely eroded the streambed. Due to this, the floodplain at Patagonia Lake “is being undercut by a feature called a headcut that funnels the floodwater into an entrenched channel rather than allowing it to spread out and soak in. Just in the past ten years this headcut has moved upstream about a mile from the east end of the lake to its present location about halfway from the lake to the Circle Z fence,” Gould wrote.

Protecting the creek from cattle grazing can help maintain, and in certain cases even improve, the health of the creek. At the TNC the Sonoita Creek has been protected from cattle grazing for over 50 years. “Of the four areas studied it has the best soil integrity and the best overall score for hydrogeomorphology (physical structure of the stream bed). It also has the best overall scores for riparian vegetation and wildlife habitat,” Gould said.

The FOSC is a volunteer non-profit organization that raises awareness and educates the community on Sonoita Creek. FOSC studies and evaluates the Sonoita Creek to provide recommendations for restoration work to improve the overall health of the riparian area.