The state of the Santa Ana River
A short observational study on the status of the Santa Ana River from samples taken between July 2007 - September 2010.
A short observational study on the status of the Santa Ana River from samples taken between July 2007 - September 2010.
Image Source: By User: Basar , via Wikimedia Commons.
The Santa Ana River is described as Southern California’s largest watershed drainage south of the Sierra, located largely in a highly urbanized, highly regulated setting. Being about 100 miles long and with more than 50 tributaries, the Santa Ana spans parts of San Bernardino, Riverside and Orange counties as it drains 2,840 square miles of land (Water Education Foundation, n.d; Santa Ana River Watershed Alliance, 2010). With time, the watershed experienced very challenging times. Areas have undergone a mining expedition not only for its drinking water and but also for its gravel (Hernandez & Sandquist, 2019). Industrial Discharges became a frequent site on the Santa Ana River, leading for it to be a focus for municipal regulation. They are the ones who have been delegated the responsibility to monitor and regulate their discharges. In the past, the EPA has wanted the local and state government to sanitize all waterways, according to the Clean Water Act. Based on its own sampling however, the EPA says the Santa Ana River’s cadmium, lead, mercury, silver, chromium and copper levels, which are toxic metals that tend to accumulate in fish, violate stringent federal standards (Cone, 1991). Likewise, the amount of trash caught in the vegetation at some of the sites after large rain events show how the sole source for this kind of trash are humans (Furnari, 2019).
Interest in revitalizing the Santa Ana River has steadily grown over the past decades, as the result of considerable contamination to the major waterway is attributed to a lack of maintenance given to the river. While cities along the Santa Ana developed in an urban sprawl, the presence of urban runoff and industrial discharge became the cyclic nature of the river. Anthropogenic effects are a big factor as to why the Santa Ana is polluted (Furnari, 2019; Mora, 2019). Yet previously, for at least 9,000 years, Native American tribal groups lived “within the watershed”, using the Santa Ana River as a source of food and water (City of Santa Ana, 2006; Furnari, 2019). As we continue to move forward with this spread of urbanization, we begin to face what Cantú (2015) describes as the next wave of challenges for the twenty-first century, challenges that force us to change how we think about water and how we manage them. Climate change, population growth, and the collapse of entire ecosystems are examples Cantú (2015) uses to underline the importance of issues that emerge with this new era. Therefore: to what extent can the Santa Ana River become a sustainable part of the local Southern California community? This presentation analyzes the river’s current condition with samples taken between July 2007 - September 2010.
In order to understand the the health status of the river, we have to know important measures such as the dissolved oxygen levels present and the amount of discharge released into the stream. I found this data from the Santa Ana Watershed Project Authority website. After downloading the GIS layers and water quality data from the Santa Ana Watershed Project Authority Website, my first mission was to organize the collected data. We have two different layers: the site locations layer and the sample data layer. The sample layer in its attributes includes the name of the site that the sample was taken from. So, what we first do is narrow down the sampling sites only to those that intersected with the Santa Ana River polygon. Then, we narrow down the samples only to those done within those four remaining sites through the use of a join to correspond each sample with the correct station.
After that, in order to further prepare my data I had to get rid of some samples within the data that were errors, errors from the station that was not able to correctly record the information. Most resulted with an -88 result. Therefore, in order to avoid that these errors have a significant influence on the result of the graph analysis I deleted them from the attribute table.
As we can see below, the four stations I am using are within a distance and follow each other. As a result, the sampling data I analyzed gives us an overall understanding of this specific area between the years of 2007-2010. With the use of the line graphs in ArcGIS Pro, we are able to see the average progression of:
SPA210FInalProject_LayoutMap
For the Santa Ana River, the stability of ecosystems greatly benefits native organisms. For this, we look at the volumetric rate of water transported. Endemic species like the Santa Ana River woolly star (Eriastrum sanctorum) greatly depend on newly deposited alluvial for its reproduction and survival (Hernandez & Sandquist, 2019; Lucas, et al., 2016). This alluvial deposits originate from sediment supply left by the water currents of the Santa Ana, especially in the floodplains. However, since 2000, the completion of the Seven Oaks Dam has reduced peak flows and reduced sediment supply. The reservoir trapped portions of the incoming sediment load, and where water did release, it tended to have less sediment than what would usually occur without the dam (Lucas, et al., 2016; Wright & Minear, 2019).
Line graph demonstrating the change in the average amount of Discharge in four-month periods.
As we see, from August 2007 through August 2010, the average amount of discharge in cubic feet per second has decreased incrementally in the Winter and Spring seasons. From the highest peak in December of 2007, each wet season has seen less discharge, caused by an accumulation of more water being retained at the dam. This redirection of water has resulted in a “significant modification of normal disturbance events of periodic flooding that is sufficient to promote a shift to an alternative state” (Lucas, et al., 2016).
Line graph demonstrating the change in the average amount of Dissolved Oxygen in four-month periods.
Freshwater bodies in a healthy state should generally have dissolved oxygen concentrations above 6.5-8 mg/L. In the Dissolved Oxygen (DO) graph above, we can clearly see is true in the Santa Ana River for the most part. From August 2007 to December 2009, DO levels tend to fluctuate between 8-10.2 mg/L. However, we see a massive drop of DO at the end of December 2009 to August 2010 where DO levels are averaging around a 6.4 mg/L.
Line graph demonstrating the change in the average pH level in four-month periods.
Now when it comes to pH level and Salinity, we see a relative and steady pace. The pH levels for freshwater should be maintained at around 6-8. The data from the stations show the Santa Ana in the August 2007 to August 2008 period at a maximum of 8.14 and a low of 7.19 while from December 2008 to August 2010 we see a noticeable stability.
Line graph demonstrating the change in the average percent of Salinity in three-month periods.
The salinity also show us a stable measurement of the Santa Ana in this regard. The line graph is closely zoomed in the 0.02 to 0.035 range of the percentage of Salinity. Nonetheless, maintaining a low salinity percentage in this range is right for preserving relatively clean freshwater.
Line graph demonstrating the change in the average percent of Turbidity in four-month periods.
Turbidity is considered a key indicator for water quality. Freshwater especially those used for consumption, as established by the WHO, should not be more than 5 NTU and is ideally below 1 NTU. We have to keep in mind that turbidity in the dry season is more indicative of the actual turbidity of the water than wet seasons in December. The wet seasons cause more fervent rain and water movement, causing a higher turbidity. Therefore, those are not indicative of the normal turbidity. As a result, the turbidity is around 4-8 NTU. This average shows the water above the standard and murkier, which is not great.
My results from the analysis in ArcGIS Pro show that the river's water quality is not great. The major indicators of water quality such as turbidity, dissolved oxygen, and salinity show that it is not stable nor is it self-sufficient. Dissolved oxygen levels are decreasing and that is essential for plant and animal life. Low discharge can lower sediment placement in the waterbed especially in floodplains, which are essential for native and rare plants. Salinity is relatively consistent and is fine, but it does not have a major factor without the support of the others. In order to improve this project, more recent samples would be great to account for the current water quality of the Santa Ana River today. Also, randomizing the samples in areas could help in the creation of heat maps or raster maps, along with interpolation maps.
Turbidity levels in the dry seasons are murky, discharge has decreased and the dissolved oxygen is lower in this period between 2007-2010. The Santa Ana River is not currently a sustainable part of the native ecosystem as it once was. Along with interventions through the construction of new canals, reservoirs, and dams, the water quality has become dependant on human intervention in order to be maintained.