Nonpoint Source Pollution on Tribal Lands
Overview of nonpoint source pollution on the Bishop Paiute Tribe Reservation
What is nonpoint source pollution?
Nonpoint source (NPS) pollution refers to pollutants that reach surface and ground water from many diffuse sources, such as rainfall, snowmelt or excess irrigation water moving over and through the ground. As this water moves, it picks up and carries away natural and human-made pollutants depositing them into lakes, rivers, wetlands, coastal waters, and even our ground water. Atmospheric deposition and hydromodification are also sources of NPS pollution.
Figure 1: Illustration showing nonpoint source pollution and point source pollution in the environment. Point source pollution can be traced back to a single identifiable source in the environment while nonpoint sources can come from anywhere making it harder to identify the source(s) and address the pollution.
Hydromodification: Although stream banks and shorelines naturally erode, anthropogenic practices which include hydromodification can exacerbate the intensity of the erosion. Hydromodification is the alteration of the natural flow of the stream or river through a landscape due to dams, impervious roads/surfaces, agricultural ditches, and channelization. Hydromodification can result in degradation of physical and chemical characteristics of surface waters, groundwater, and aquatic and riparian habitats by changing the water's natural temperature, flow and sedimentation loading.
Atmospheric Deposition: The process where particles, aerosols and gases move from the earths atmosphere onto the earth surface, are also nonpoint source pollutants that may enter our waterways from anywhere in the environment. Dry atmospheric deposition is the dispersion of gases, particles, and aerosols from the atmosphere to the environment. Wet atmospheric deposition occurs when these gases or aerosol mix with atmospheric water and then falls onto the environment as rain or snow. Most pollutants deposited from the atmosphere are manmade, however, naturally occurring gases, particles and aerosols also contribute to NPS pollution, for instance, sand particles, ash from fires and aerosols from volcanoes, can all be deposited in populated and remote areas.
Figure 2 : Illustration shows both dry and wet atmospheric deposition from the atmosphere to the environment.
Where does NPS pollution occur?
NPS pollution can occur anywhere! This includes agricultural, urban/residential, and natural settings. For instance, recent studies have discovered that microplastics have reached remote locations (e.g., Arctic, Antarctic, and depths of the oceans) not only by ocean currents but through the air, snow, and fog all while crossing various continents, countries, and vast oceans.
In comparison, point source pollution is any single identifiable source of pollution from which pollutants are discharged, such as a pipe, ditch, ship or factory smokestack. Factories, sewage plants and mining operations are the most common point source pollution. Because the pollutants are easily traceable to the main source, addressing point source pollution can be easier than addressing nonpoint source pollution that is occurring from anywhere.
What are the types of NPS pollution?
Agriculture: NPS pollution from agriculture can be attributed to runoff from irrigating crop field and pastures that makes its way to a nearby stream, river, lake, costal waters, etc. Some of these pollutants include excessive amounts of total nitrogen and total phosphorus, which are found in most fertilizers. Although nutrients are great for cultivating plants, excessive amounts can actually hinder the soil and contribute to the degradation of the water quality in nearby waterbodies. Excessive nutrients can also cause Harmful Algal Blooms(HABs) that contain cyanobacteria. Cyanobacteria is harmful to humans, pets and other animals that come into contact with the contaminated water.
Figure 3: Cattle can severely modify the environment if proper grazing management is not in place.
Another agricultural culprit contributing to NPS pollution is cattle grazing. As cattle graze near streams, rivers, lakes, etc., they contribute to bank erosion by removing or trampling the riparian vegetation holding the soil together. This increase in sedimentation entering the waterbody can affect fish habitats and other aquatic species that depend on low amounts of sediment in the water for reproduction. Cattle dung or poop is also a major contributor to increases in pathogenic bacteria in waterbodies including total coliform and fecal coliform, particularly E. coli. Coming into contact with these pathogens can increase the risk of contracting a water-borne illness. Proper grazing management is incredibly important to reduce the amount of pollutants entering our waterways as well as decreasing bank erosion and maintaining healthy riparian areas.
Urban and Residential: NPS pollution can also be found in urban and residential areas where runoff from rain and irrigation can pick up pollutants and deposit them into nearby streams, rivers, lakes, coastal waters, etc. These pollutants include: oil, grease, and other toxic chemicals from cars, herbicide/pesticides and manure from gardens and lawns, viruses, bacteria and nutrients from dog poop and trash that has not been disposed of properly, road salts, heavy metals from roofs and other motorized equipment. All these pollutants can make their way to a waterbody after a storm or other irrigation practices (e.g., irrigating lawns/gardens, washing cars, etc.). These pollutants can harm wildlife, native vegetation, and recreational activities.
Natural: NPS pollution also occurs naturally in the environment. Examples of naturally occurring NPS pollution affecting water quality include sedimentation, pathogenic bacteria, heavy metals and hydromodification. Due to excessive flooding, natural bank erosion is inevitable, this can increase the amount of sediments in a waterbody, affecting fish and other aquatic life. Increases in pathogenic bacteria are caused by defecation from mammalian species in or around a waterbody. Heavy metals (e.g., arsenic, cobalt, cadmium, mercury, etc.) are naturally occur metals in rocks and minerals in the environment that break down and enter the waterbodies. Hydromodification occurs when a stream or river is altered from its natural state changing the flow of the water. This can affect groundwater levels, aquatic life and riparian habitats. In a natural setting, hydromodification is caused by beaver dams, fallen trees, and debris buildup.
Figure 4: Evidence of hydromodification from a beaver dam on the North Fork of Bishop Creek. Notice the change in flow caused by the dam. This is a form of naturally occurring NPS pollution.
What type of NPS pollution occurs on the Reservation?
The primary nonpoint source pollutants affecting the Bishop Paiute Reservation are pathogens, sedimentation, and erosion. This pollution is caused by a variety of sources and activities, including flood irrigation practices, livestock grazing, and hydromodification projects further upstream off of the Bishop Paiute Reservation.
Figure 5: Evidence of erosion due to floods cutting at the bank and exposing tree roots along the Nork Fork of Bishop Creek.
Both forks of Bishop Creek suffer from streambank erosion on the reservation due to hydromodification both on and off the reservation and flooding from extreme weather events and irrigation practices. Bank erosion on the reservation is also naturally occurring, but intensified by hydromodification, grazing and excessive flooding. Varying discharges caused by the hydromodification upstream of the reservation is a major contributing factor to increase streambank erosion on the reservation. Once streambank erosion takes place, it does not return back to normal. The exposure of tree roots can cause the trees to topple over and create dams that change the flow of the stream or river.
Bishop Creek was classified as an impaired waterway (303(d)) by the US Environmental Protection Agency (EPA) in 2022 due to the heightened levels of pathogenic bacteria - fecal coliform and Escherichia Coli (E. coli) in the water. The main sources of these pathogenic bacteria were determined to be from cattle.
Figure 6: Full cattle access to water can be the source of major water quality issues as banks are eroded, riparian areas destroyed, and pathogenic bacteria levels are increased.
Figure 7: Evidence of trash on the banks of the North Fork of Bishop Creek.
Another form of NPS pollution on the reservation is the improper disposal of trash. Unfortunately, trash along the banks of Bishop Creek is common. Trash causes the water quality of Bishop Creek to change and affects the aesthetics of the surrounding environment.
What is the Water Quality Control Program doing about NPS pollution on the Reservation?
The Water Quality Control Program (Water Program) in the Environmental Management Office (EMO) for the Bishop Paiute Tribe, has been monitoring and managing the north and south fork of Bishop Creek within the reservation boundaries since 1998. The Water Program monitors various water quality parameters on a weekly and monthly basis and addresses water quality issues as they emerge.
The Water Program was first to sound the alarm on the increased levels of E. coli in Bishop Creek on the Bishop Paiute reservation in 2010. Since then, continuous monitoring has been in place to determine the temporal and spatial spikes of pathogenic bacteria in the creek. The Water Program has been working with local stakeholders, the Lahontan Water Board, Los Angeles Department of Water and Power, and others to address pathogenic bacteria impairments of water quality in Bishop Creek. The Bishop Creek Vision Plan , 2022, is expected to improve water quality levels by reducing the pathogenic bacteria in Bishop Creek.
Other efforts to address NPS pollution by the Water Program include bank stabilization by planting native species in riparian areas along the creek, exclusionary fencing to reduce cattle from entering the creek, working with ranchers to develop best management practices for cattle grazing, manure management, trash pickup, outreach and education, and many more!
Figure 8: Various NPS pollution projects that current and former Water Program staff have conducted over the years.
What can you do to reduce NPS pollution?
You can reduce nutrients, bacteria and other pathogens from contaminating the waterways by practicing the proper disposal of trash as well as human and pet waste, fixing leaky septic tanks and having them regularly inspected, limiting the amount of fertilizer/pesticides/herbicides put on lawns and gardens, reducing flood irrigating practices, adopting best management practices for cattle grazing, maintain proper automobile care and properly dispose of automobile and household chemicals (e.g., oil, antifreeze, paint, etc.), reduce the use of single-use plastics, clear out litter, leaves and debris from gutters and storm drains, volunteer at local cleanup events, and encourage local officials to address NPS pollution by developing sediment and water quality control ordinances in your community.
More information:
If you would like more information on NPS pollution or the efforts that the Water Program is doing on the reservation, please feel free to contact the Water Quality Program Coordinator at brianda.hernandez@bishoppaiute.org, or visit us here. Follow us on social media!
