A Warming River
The sun’s energy is needed to support all life on Earth. Human progress and population growth has led to burning of more fossil fuels, upsetting the balance of this energy in the atmosphere and warming the planet. We are witnessing the impacts of this increasing temperature globally, but also right here in Spokane. This report summarizes how a warming planet is affecting our river, its tributaries, and ecosystems. We discuss the policies intended to maintain healthy river temperatures, how these policies should be implemented, and how our community can make changes to benefit the river that contributes so much to our watershed.
Heat and river ecosystems
On June 29th, the air temperature in Spokane reached 109°F (42.8°C), the hottest temperature in 140 years of record. Our data analysis shows how these air temperatures have a significant and direct impact on our river.
Graph showing how air temperatures are associated with water temperatures in the Spokane River during the summer of 2021.
As increased water temperatures occur in the Spokane River with greater frequency and for prolonged duration, this impacts the river ecosystem in several ways.
The metabolic rate of fish and other aquatic organisms increases, which requires more oxygen. Unfortunately, as water warms, it holds less and less oxygen. At very high temperatures, coldwater fish, like our native redband trout, are literally fighting to breathe, and using all their energy to do so. This leaves little energy for growth, and summer is the time when fishes in temperate climates like Spokane experience 90% of their yearly growth (Ficke et al., 2007).
Young redband trout. Water temperature standards are set to ensure the survival of this native species.
Photo credit: Tim Connor photography
Warmer water can also increase numbers of bacteria and parasites, and because fish are already stressed by the heat, their immune systems are not as capable of fighting off diseases (Ficke et al., 2007). Protozoan infections like whirling disease or “Ich” (Ichthyophthirius multifiliis) can be fatal to trout and easily spread if fish are congregating in cooler pools in the river.
The toxic effects of certain chemicals (e.g., pesticides and heavy metals) on fish also increase with elevated water temperature (Ficke et al., 2007). We know metals like zinc and lead are in our river from historical mining upstream in the Coeur d’Alene basin. As we discussed, coldwater fish are breathing more rapidly in warm water and this increases their uptake of these dangerous pollutants.
An increasingly warm Spokane River will limit the habitat for native coldwater fish like the redband trout. In general, rainbow trout prefer temperatures below 20°C (68°F) and grow best in temperatures between 13-17°C (~55-63°F) (Bear et al., 2007). When water temperatures exceed these levels, fish look for cooler refuges. In a summer like 2021, with low river flows, sanctuaries like these are hard to find in a habitat that is already fragmented by the seven dams on the river, all without fish-passage. Redband trout also have to compete for this limited habitat with increasing numbers of fish acclimated to warmer water, like smallmouth bass and yellow perch.
Map of the seven dams on the Spokane River, none of which have fish passage.
In this graph, you can see how low flow in the river (blue line) occurred this summer when temperatures were above 17°C (63°F), which is not ideal for growth of redband trout. This limits the number of cooler pools in the river for fish to escape the heat.
Flow in Spokane River at Sandifur Bridge on August 21, 2021, was 733 cubic feet per second. These low flows can block passage for fish looking for cooler water refuges.
Water quality standards and fish
Temperatures above 25°C (77°F) are often lethal for rainbow trout species (Matthews & Berg, 1997). Washington State Department of Ecology (Ecology) is responsible for setting water quality criteria for designated uses, including protection of aquatic life. Designated uses in the Spokane River include Salmonid Spawning, Rearing, and Migration. Under this rule, water temperature cannot exceed an average daily maximum of 17.5°C (63.5°F) during a 7-day period, or a single day maximum of 20°C (68°F).
If the 7-day average of the daily maximum or the 1-day maximum is exceeded twice in a single year, then the Department of Ecology will list that waterbody segment on the Clean Water Act 303(d) list of Impaired Waters. This list is submitted to the U.S. Environmental Protection Agency (EPA) for review and requires a Total Maximum Daily Load (TMDL) plan, pollution control program, or actions to ensure water quality standards are restored for these segments of the river.
Two segments of the Spokane River are already on the Impaired Waters list for temperature, stretching from the Idaho state line to Myrtle Point near Plante’s Ferry Sports Stadium. Despite being listed 25 years ago, these portions of the river still do not have a TMDL in place for temperature.
Sections of the Spokane River already on the EPA list of Impaired Waters shown in red (Washington State Department of Ecology Water Quality Atlas)
Our river connects to our aquifer. In locations like Barker Road we expect to see these high temperatures as the river is fed mainly by warm surface water from Lake Coeur d’Alene. At Sullivan Road, the aquifer begins to feed the river with cold water, keeping temperatures downstream safe for fish.
Map showing portions of the Spokane River that lose water to the aquifer (in gold), areas that gain water from the aquifer (in blue), and areas where interaction is minimal or varies depending on river flow (in green) (City of Spokane Wastewater Management, 2015). The river does not receive any cold aquifer water until it reaches Sullivan Road. Water in this section of river consists only of surface water from Lake Coeur d’Alene, which can get very warm in the summer.
In late June, there was still a large amount of warm water from Lake Coeur d’Alene being spilled over the Post Falls Dam. The heat wave made that water even warmer, diluting the cold aquifer water entering the river at locations like Islands Trailhead. We were able to record these effects at three locations - Islands Trailhead, Above Upriver Dam near Minnehaha Climbing Rocks, and at the Division Street bridge - all of which had violations of the 7-day average of the daily maximum.
Graph showing temperatures exceeding the 7-day average of the daily maximum threshold of 17.5°C. This was observed at three locations not yet on the EPA Impaired Waters list: Islands Trailhead (in red), above Upriver Dam (in green), and Division Street (in orange).
We also observed violations of the 1-day maximum of 20°C at Islands Trailhead and Above Upriver Dam.
Graph showing temperatures exceeding the 1-day maximum threshold of 20°C. This was observed at Islands Trailhead (in orange) and above Upriver Dam (in gray).
If we continue to experience extreme heat earlier in the summer, when river flows are still high from spring runoff, this will have negative impacts on the river ecosystem, especially for young fish.
Jule Schultz, Spokane Riverkeeper Program Director, and Chastity Kolb, thermal science Intern, recording temperatures in the Spokane River at Division Street Bridge.
Temperature data we recorded this summer will be submitted to the Department of Ecology for review. If Ecology uses our data in future Water Quality Assessments, then segments of the river near Islands Trailhead and Above Upriver Dam should be added to the Impaired Waters list.
The Department of Ecology has a duty to protect aquatic life in the Spokane River by developing a plan to improve temperatures for native species like the redband trout. Permits for dischargers will need revision to provide limits on temperature for treated wastewater entering the river.
What else is causing the river to warm?
Though warming global temperatures will have a tremendous impact on our river, additional causes should be explored and managed. Dams are known to influence water temperatures; those that release warm surface water will cause temperatures to increase downstream. Conversely, dams releasing cold water from the bottom of a reservoir will decrease temperature downstream.
All seven of the dams on the Spokane River generate hydroelectricity. Hydroelectric dams generate power using different techniques or designs, which affect river temperatures in different ways. For example, the three Spokane River dams used in our temperature study (the Upriver, Upper Falls, and Monroe Street dams) are run-of-river facilities with little water storage capacity (City of Spokane Public Works & Utilities, n.d.; GEI Consultants, Inc., 2004). Run-of-river hydroelectric dams divert water through a pipe or channel to the turbines inside of the power station and then back into the river (Office of Energy Efficiency & Renewable Energy, n.d.). Changes to temperature above and below run-of-river dams is not always significant; however, several studies have shown slight increases in downstream temperatures, an effect compounded by low summer flows (Gibeau et al., 2017).
Included in this 2021 report are temperatures above and below Upriver Dam and above and below the Upper Falls and Monroe Street dams. Based on the previous research, one would expect run-of-river facilities such as these to show increased temperatures below the dams. At Upriver Dam, we saw the opposite effect; temperatures above the dam were actually higher than below the dam. This could be because above Upriver Dam the river is losing water to the aquifer, whereas below the dam the river is gaining cool aquifer water (SAJB, 2004). Another explanation could be placement of our temperature loggers closer to the river bank, instead of in the deeper portions of the reservoir. Upper layers of a reservoir are warmer in the summer.
Graph showing the temperature difference above Upriver Dam (in blue) and below Upriver Dam (in orange). Temperature was warmer above the dam at this location.
At the Upper Falls and Monroe Street Dams, we compared temperatures above the dams at Division Street Bridge and below the dams at Redband Park. Both of these locations are within a section of the river that has minimal interaction with the aquifer (City of Spokane Wastewater Management, 2015); hence, a more reliable comparison. We did observe increased temperatures at Redband Park, which lies below the dams, however it was not a significant difference. More study is necessary to determine the true effects of these dams on temperatures in the Spokane River.
Graph showing temperature difference above (in blue) and below (in orange) Upper Falls and Monroe Street dams. Temperature was warmer below the dams at Redband Park.
Land development can also influence temperatures in rivers and streams, like the densely populated areas along the Spokane River in Kootenai County and Spokane County. Such urban and suburban landscapes affect river water temperature in several ways. Reduced tree cover from land development diminishes the benefits of shade along the river bank. Stormwater runoff from warm concrete or asphalt can directly increase temperatures in the river while also contributing to sediment pollution. Our large communities also compete with the river for cool aquifer water, which is critical to maintain summer water temperatures and flow, providing ample habitat for native cold water fish. In areas where the aquifer feeds the river, our data show temperatures are 4.6°C (40.3°F) lower, on average, than in areas where the river loses water to the aquifer. Imagine how hot the river would be without that cold aquifer water!
What can we do to address warming temperatures in our river?
There are several reasons why temperatures in the Spokane River are increasing and vulnerable aquatic habitats have been, and continue to be harmed. There is no single solution. If we are to protect the Spokane River ecosystem and reverse these effects, we can address these issues in several ways.
Gather information to determine how dams are affecting our river and if the benefits of hydroelectricity truly outweigh the cost to native fish and other wildlife dependent on the river.
Reduce and control stormwater drainage by converting impervious surfaces, like parking lots, to include more trees and less pavement.
Plant green rooftops, rain gardens, and vegetated strips along roadsides to collect and filter stormwater before it can reach the river.
Restore riparian habitat with native trees and shrubs (e.g., willows, dogwood, alder) which provide shade to cool the river and its tributaries in the summer. Such work is already being done in the Hangman Creek basin by many of our partners - Coeur d’Alene Tribe, Lands Council, and Department of Ecology.
Reducing outdoor water usage in the summer by replacing lawns with native, drought tolerant vegetation, or using smart irrigation practices reserves more cold aquifer water for the river.
Counter a warming climate together. As a community, join the global effort to reduce greenhouse gas emissions by supporting local legislation like the Spokane Sustainability Action Plan. Individual efforts like improvements to make your home or business more energy efficient, reducing air travel, or eating more locally grown vegetables and less meat, are all ways we can do our part.
Hangman Creek
Lower Hangman Creek flows through the outskirts of Spokane and is characterized by basalt cliffs and riparian vegetation.
Hangman Creek is a large tributary of the Spokane River with a watershed that spreads over 689 square miles in Washington, Idaho, and the Coeur d’Alene Tribal Reservation (Snouwaert & Noll, 2011). Prior to colonization, the landscape of this region consisted of bunchgrass prairie, Ponderosa pine forest, and native riparian trees along the creeks and streams (e.g., willows, aspen, cottonwood) (Snouwaert & Noll, 2011). The creek was home to trout, salmon, and freshwater mussels, important food sources for ancestors of the Coeur d’Alene Tribe (Percy, n.d.). In the early 1900s, much of the land in the Hangman Creek Basin was altered for agricultural use. Sections of Hangman Creek and its tributaries were straightened, ditches were constructed to drain the surrounding wetlands, and acres of forest and shoreline vegetation were cut down (Snouwaert & Noll, 2011). These changes have led to multiple water quality issues in the Hangman Creek watershed, including murky water caused by bank erosion and runoff from farmland, nutrient pollution from fertilizers, fecal bacteria from livestock, and elevated water temperatures due to loss of tree cover.
As we learned, elevated river and stream temperatures are unhealthy for native coldwater fish. Planting native riparian trees along Hangman Creek and other streams in the watershed is the best way to reestablish water temperatures favorable to redband and cutthroat trout and future migrations of Chinook salmon. The Coeur d’Alene Tribe, Spokane Tribe of Indians, Lands Council, Spokane County Conservation District, Spokane Falls Trout Unlimited, Inland Northwest Lands Conservancy, Washington Department of Ecology, and Spokane County are all contributing to restoration efforts on the banks of Hangman Creek and its tributaries.
Like the Spokane River, streams in the Washington portion of the Hangman Creek Basin have water quality standards to protect salmonids like trout and salmon:
7-day average of the daily maximum set at 17.5°C (63.5°F)
Daily maximum set at 20°C (68°F)
This graph shows daily temperatures reached or exceeded 20°C from late May until mid-August in Hangman Creek at the mouth and Waverly-Roberts Road, and in Marshall Creek. Little Hangman Creek also saw these elevated temperatures from late May through mid-July.
The 7-day average of the daily maximum temperature rule was also violated at least once at all of our monitoring locations in the Hangman Creek Basin.
Idaho has slightly different water quality standards for streams that support coldwater aquatic life:
Water temperatures of 22°C (71.6°F) or less
Maximum daily average of no greater than 19°C (66.2°F) (Idaho Department of Environmental Quality Surface and Wastewater Division, 2021)
Daily water temperatures in Hangman Creek, according to the Idaho Department of Environmental Quality, are not to reach or exceed 22°C due to human activities. We recorded temperatures above 22°C in Hangman Creek at our DeSmet location.
We also observed daily average temperatures above 19°C at this location in the creek throughout June, July, and August.
These data show that more work needs to be done in the Hangman Creek Basin to ensure water temperatures are not reaching these high levels that are unhealthy for coldwater fish populations. Anthropogenic land use practices such as removal of riparian vegetation and disconnecting the flood plains degrade water quality, especially temperature, throughout the watershed. Planting of native grasses, shrubs, and trees along creeks and streams will not only provide shade to cool the water, but will also reduce bank erosion, capture sediment and nutrient pollution, and increase biodiversity and abundance of insects that are important food sources for trout. Spokane Riverkeeper continues to steward these efforts in the Hangman Creek watershed, protecting water quality for fish and wildlife through advocacy.
Jule Schultz placing a temperature logger in Hangman Creek near Waverly, Washington. This portion of Hangman lacks native riparian vegetation important for maintaining water temperatures. Instead we see tons of nonnative reed canary grass has invaded the creek bank. Restoring native grasses, shrubs, and trees will not only help shade the creek, but will also improve habitat diversity and overall health of the creek ecosystems.
References
Bear, E. A., McMahon, T. E., & Zale, A. V. (2007). Comparative thermal requirements of westslope cutthroat trout and rainbow trout: implications for species interactions and development of thermal protection standards. Transactions of the American Fisheries Society, 136: 1113-1121. https://www.montana.edu/mcmahon/documents/cttxrbt%20temp%20TAFS.pdf
City of Spokane Public Works & Utilities. (n.d.). Upriver Dam. https://my.spokanecity.org/publicworks/water/upriver-dam/
City of Spokane Wastewater Management. (2015). [Map of Spokane Valley-Rathdrum Prairie groundwater interaction with the Spokane River].
Ficke, A. D., Myrick, C. A., & Hansen, L. J. (2007). Potential impacts of global climate change on freshwater fisheries. Reviews in Fish Biology and Fisheries, 17, 581-613. https://doi.org/10.1007/s11160-007-9059-5
GEI Consultants, Inc. (2004, May). Intermountain Province Subbasin Plan. https://www.nwcouncil.org/subbasin-plans/intermountain-province-plan
Gibeau, P., Connors, B. M., & Palen, W. J. (2017). Run-of-river hydropower and salmonids: potential effects and perspective on future research. Canadian Journal of Fisheries and Aquatic Sciences, 74(7), 1135-1149. http://dx.doi.org/10.1139/cjfas-2016-0253
Idaho Department of Environmental Quality Surface and Wastewater Division. (2021). IDAPA 58.01.02 - Water Quality Standards. https://adminrules.idaho.gov/rules/current/58/580102.pdf
Matthews, K. R., & Berg, N. H. (1997). Rainbow trout responses to water temperature and dissolved oxygen stress in two southern California stream pools. Journal of Fish Biology, 50: 50-67. https://www.fs.fed.us/psw/publications/matthews/psw_1997_matthews003.pdf
Office of Energy Efficiency & Renewable Energy, U.S. Department of Energy. (n.d.). Types of hydropower plants. https://www.energy.gov/eere/water/types-hydropower-plants
Percy, J. (n.d.). Hangman Creek. Spokane Historical. Retrieved November 8, 2021, from https://spokanehistorical.org/items/show/693
Snouwaert, E., & Noll, R. (2011). Hangman (Latah) Creek Watershed fecal coliform bacteria, temperature, and turbidity Total Maximum Daily Load Water Quality Implementation Plan (Publication No. 11-10-012). State of Washington Department of Ecology. https://apps.ecology.wa.gov/publications/documents/1110012.pdf
Spokane Aquifer Joint Board (SAJB). (2004). The Spokane Valley‐Rathdrum Prairie Aquifer Atlas. https://www.spokaneaquifer.org/2004SVRPAquiferAtlas.pdf
Washington State Department of Ecology. (accessed 2021, November 17). Water Quality Atlas [interactive map showing water quality assessment of surface waters]. https://apps.ecology.wa.gov/waterqualityatlas/wqa/map
Washington State Department of Ecology Water Quality Program, Environmental Assessment Program, Toxics Cleanup Program. (2020, July). Water Quality Program Policy 1-11 Chapter 1: Washington’s water quality assessment listing methodology to meet Clean Water Act requirements (Publication no. 18-10-035). https://apps.ecology.wa.gov/publications/documents/1810035.pdf