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Aug 27 , 2010
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Note the white sandbags, called weirs, lined up in the Spokane River. These temporary dams help divert
water during the aesthetic spill tests. They will be removed from the river once testing is complete. |
We received this message to conversation@avistautilities.com yesterday from a concerned customer. I thought this might be a question that other customers may be asking, so I’ve posted the full e-mail and our reply below.
E-mail
I have seen the crews at work on the Aesthetic Spill Pilot Test in the River Front Park area. It appears the purpose of this pilot test is to assess the feasibility of diverting water that would normally flow through the south channel to the north channel. Do any practical benefits exist for this kind of diversion? Or, as the pilot study name suggests, are the benefits purely aesthetic?
If the no practical benefits exist, I object to the use of my utility rates for a purely aesthetic project which only benefits a small portion of the rate paying customers.
Please shed some light on the driving force for this project.
-Jesse
Reply
Dear Jesse, Thanks for your inquiry about the work being done on the Spokane River channels in Riverfront Park.
As you may know, we received a new operating license for our hydro facilities last year. With the new license came some new conditions that we are required to meet. Among those is an aesthetic spill in the north and middle channels of the river.
Currently the requirement is for a minimum 500 cfs to be diverted from the south channel. But there is a provision in the license that allows us to attempt to modify the riverbed so that we can make the flows just as appealing with only 300 cfs.
What we are doing is filling in the artificial cuts in the rock that were done in the early days of Spokane’s development. These were done to divert naturally low river flows to various mill wheels and laundries, etc. Those same cuts prevent the aesthetic affect that people want to see in the river.
Presently we have a group of stakeholders evaluating the modified river flows for the most effective configuration. Once that is established we can begin to make permanent modifications and hopefully divert less generating water from the powerhouse at Upper Falls.
I hope that addresses your concerns. Please let me know if you have further questions.
-Hugh Imhof, Avista Communications Manager
Aug 25 , 2010
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The evaluation team takes a look at the river from one of 10 public viewpoints Wednesday morning,
August 25. The group will suggest changes to the temporary dams and come back for a second and
possibly third look at spills through the two channels. Evaluators include representatives of Spokane Parks
and Recreation, Spokane Canoe and Kayak Club, Sierra Club, Washington Department of Ecology, Center
for Environmental Law and Policy, Avista, Friends of the Falls, and others. |
Normally at this time of the year, the north and middle channels of the Spokane River in downtown Spokane, what many of us know as Spokane Falls, look pretty dry. That’s because in the past during the dry summer months, natural conditions and Avista’s hydropower operations have resulted in little or no flow through that part of the river. That all changed last year with the issuance of Avista’s new 50-year Federal Energy Regulatory license to operate our Spokane River Project, which includes Upper Falls and Monroe Street Dams in downtown Spokane. As a result of the relicensing process, we must now release minimum aesthetic spills around the clock at both Upper Falls and Monroe Street. That began this summer, and you may have noticed more water flowing through the falls in July and early August.
But there’s more to it than that. If you’ve been to Riverfront Park in the past couple of weeks, you’ve probably noticed something else in the river. Cranes, sandbags, and workers have been busy preparing for an aesthetic spills pilot test at Upper Falls Dam. This test will help us determine whether permanent channel modifications can be made to bring the riverbed closer to its natural state, the way it was before early developers in Spokane cut into the bedrock to divert the water during dry times. We’re hoping to enhance aesthetic appeal even more during periods of low river flow. Our license requires us to do this study to learn whether the same, or a better, aesthetic effect can achieved with daytime releases of 300cfs and channel modifications, as the current daytime release of 500 cfs does, without modifications.
Avista’s Upper Falls Dam is located where the river splits into two channels around Havermale Island in Riverfront Park. The southernmost channel forms the forebay that provides water to the powerhouse, and the northern channel passes through the control works dam and splits again into two smaller channels that run north and south of Canada Island. These are referred to as the north and south (or middle) channels. These two channels are where the pilot test is occurring, and we hope that as a result of this work, viewers of the river downtown will have a pleasant experience no matter what time of year it is.
Last week we temporarily interrupted normal aesthetic spills and placed several small, temporary dams made with sandbags, called weirs, throughout the channels. These weirs divert the flow of water throughout the channels, and this week, an evaluation team made up of representatives of stakeholders, agencies and the public is viewing test spills and giving their feedback as we release 300 cfs through the two channels. Team members will make judgments based on their sense of sound, coverage, depth and power of the water as it moves through the channels. The feedback we receive will help us determine whether to move forward with permanent channel modifications next year.
Next week, we’ll remove all of the equipment and materials from the river, and we’ll return to normal aesthetic spills the following week. Then, if the outcome of the pilot test shows us that permanent modifications are the way to go, the real work begins.
So far, we’re excited about the potential of this project. We’re hoping the result is a cascading waterfall effect throughout both channels of the river that visitors and the community can enjoy all summer long. And this collaborative effort could indeed accomplish that, possibly restoring at least some of the river’s natural beauty that was lost through the development of Spokane over the past 100 or more years.
Aug 17 , 2010
play video
Hey, everyone. I wanted to share a quick clip of the video I took on the Spokane River last week.
This video shows the removal and relocation of accumulated rock, gravel and sediment at Monroe Street Dam. The crane grabs the materials and places them over the dam and back into the river. This material is the stuff that naturally flows downriver, but collects behind the dam.
My co-worker Communications Manager Anna Scarlett told me that analytical results of materials sampled back in July indicated that sediments were within Washington’s acceptable standards for contaminants. Relocation of the materials over the spillway back into the river is required by federal and state permits to operate the project, and redistributing the materials back into the river will allow them to continue to serve as a potential gravel source for spawning habitat in the Spokane River system.
More work on the river will continue in the next few weeks as we study whether channel modifications can be made to enhance aesthetic flows in the north and middle channels during periods of low river flow.
Jul 19 , 2010
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The Spokane River through downtown Spokane. |
One year into our new FERC license on the river, big projects happening
Watch for activity on the downtown Spokane stretch of the Spokane River beginning this week, as Avista starts work on several projects to protect and enhance fish, wildlife, water quality, recreation, cultural and aesthetic resources related to our Spokane River hydroelectric project.
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Click to view a map of the activities happening on
the Spokane River. | Over the next few months, visitors to the stretch of the river between Upper Falls and Monroe Street Dams will see equipment and temporary work structures in and around the river, including a crane near the river above Monroe Street Dam, intermittent aesthetic flows at Upper Falls Dam, sandbags, water bladders and moving equipment in the Upper Falls area. All of the equipment will be handled and operated with an emphasis on public safety and protecting the surrounding environment.
Work taking place includes a pilot study in the north channel of the river to learn what modifications can be made in order to return the river to a more natural state, and removal of accumulated rock, gravel and sediment at Monroe Street Dam. The work will begin in July and August as flows drop to their summer levels, and could be extended into early autumn.
While fishery work may not be as visible as other activities, it’s just as important. While we’re studying the river channel, biologists and contractors will be working in the stretch of the river between Upper Falls Reservoir and Monroe Street Dam, primarily on a study to assess whether fish can become trapped or stranded in the north channel of the river when water levels are low.
In late June, 3,000 catchable, sterile rainbow trout were planted in Upper Falls Reservoir. Another 3,000 fish will be planted in Upper Falls Reservoir this fall. The first year of a three-year fish population assessment will also be conducted in the Upper Falls Reservoir this fall.
Watch for updates as we progress, and see the attached map and handout for specific details, locations and approximate dates/timelines.
A year into the 50-year Federal Energy Regulatory Commission license to operate our five hydroelectric dams on the Spokane River (Post Falls, Upper Falls, Monroe Street, Nine Mile Falls and Long Lake), the work Avista will do is just getting started. These significant environmental measures will benefit both the communities and the natural resources where our facilities are located. Protecting resources and responsibly operating our dams helps us continue to generate low-cost, renewable hydroelectric energy. Jul 16 , 2010
The installation of new operable spillgates at Nine Mile Dam began this week as Avista finished drawing down Nine Mile Reservoir Thursday to allow a work barge and crew to begin. The upgraded system will allow Avista to pre-program desired heights and give operators the ability to raise and lower the height of the spillway at any time, incrementally if needed, in order to maintain the reservoir pool at a more constant level throughout the entire year.
The reservoir level must be lowered during construction to allow the contractor to erect the new spillgates. During construction, the pool level will be 2 to 4 feet below the spillway crest (about 12-14 feet below full pool), which may be lower than what it has been in the past when the flashboards were erected each year in mid-summer.
As a side note, to announce this news, this week we used a new e-mail tool for communicating directly with customers, river users, property owners and stakeholders interested in operational and environmental activities related to our Spokane River Project. This is one more way we’ll try to get information about river and reservoir levels, stewardship work and other river operations to folks quickly and directly. If you’re interested in being part of Avista’s mailing list for Spokane River News, send an e-mail to spokanerivernews@avistacorp.com. Jul 06 , 2010 Water levels allow spill gates at Post Falls Dam to be closed
Avista is advising Spokane River users that river recreation is now permitted in the area between the Spokane Street Bridge and the Post Falls Dam. River volumes have dropped sufficiently to allow the spill gates at the dam to be closed.
The City of Post Falls boat launch at Q’emiln Park is expected to be opened to the public today. Typically this occurs sometime between Memorial Day and the July 4 holiday. The median date for closing the gates is June 22; however the date has occurred as late as July 8 in 2008 and as early as May 22 in 2005.
Avista expects summer operation at the dam to continue through Labor Day, as long as weather conditions allow. River users are cautioned that weather conditions can cause rapid changes in water levels. Please exercise caution when using the waterways.
For current information on Spokane River flows and Coeur d'Alene Lake elevation (includes anticipated changes in flow and elevation for the coming week) call 208-769-1357. For information on Spokane River flows and Lake Spokane elevation (includes anticipated changes in flow and elevation for the coming week) call 509-495-8043.
Jul 02 , 2010
High water conditions require open spill gates at Post Falls Dam
Avista is advising Spokane River users that boating and swimming remain prohibited in the area between the Spokane Street Bridge and the Post Falls Dam through the holiday weekend. Last week’s heavy rainfall in North Idaho has resulted in higher than normal flows in the Spokane River and Avista must spill the extra water. Because of the open spill gates, it is not safe to be in the water above the dam and a Post Falls city ordinance prevents river use in that area.
Once the spill gates can be closed the Q’emiln Park boat launch will be opened and river recreation can resume. Typically this occurs sometime between Memorial Day and the July 4 holiday. In recent years the median date for closing the gates has been June 18, however the date has occurred as late as July 8 in 2008 and as early as May 22 in 2005.
Avista expects to begin summer operation at the dam as soon as weather conditions allow.
The river above the Spokane Street Bridge and Coeur d’Alene Lake are accessible with several relatively close public boat launches open. They include the launch at Blackwell Island, Third Street Launch, Higgins Point, Boothe’s Landing and Mica Bay.
For current information on Spokane River flows and Coeur d'Alene Lake elevation (includes anticipated changes in flow and elevation for the coming week) call 208-769-1357. For information on Spokane River flows and Lake Spokane elevation (includes anticipated changes in flow and elevation for the coming week) call 509-495-8043.
River users are cautioned that weather conditions can cause rapid changes in water levels. Please exercise caution when using the waterways.
Jun 21 , 2010
Heavy rains require action, lowering of river
Avista will need to open additional gates at the Post Falls Dam today to allow the increased flow in the Spokane River to pass by the dam. This action is due to a large amount of rain in the North Idaho mountains over the last 24 hours which is causing Coeur d’Alene Lake to rise.
Avista is waiting to open the biggest gate until this afternoon to allow Spokane River users to move their boats and equipment to a safe location in the river. The elevation of the river near the Spokane Street Bridge this morning is about 2,124.8 ft., which is about 3 feet below summer level. Once the bigger spill gate is opened the river level will drop as much as 7 feet below summer level.
Coeur d’Alene Lake is currently slightly above its normal summer level of 2,128 ft. above sea level which Avista is required to maintain until after Labor Day.
As more water flows in the Spokane River between the lake and the dam, Avista must open more spill gates to allow the water to pass so that the lake remains at or near 2,128. The more spill gates that are open, the lower the elevation of the water above the dam, near the Spokane Street Bridge.
Boaters and other river users are reminded that weather conditions can cause rapid changes in river levels. Please exercise caution on the water.
Jun 17 , 2010
This summer and fall, Avista will replace the wooden flashboards at Nine Mile Hydroelectric Development with operable spillgates. The upgraded system will allow Avista to pre-program desired heights and give operators the ability to raise and lower the height of the spillway at any time, incrementally if needed, so that we can maintain the reservoir pool at a more constant level throughout the entire year.
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Click above to enlarge graphic. |
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Click above to enlarge graphic. | What will the new spillway consist of?
The new spillway will consist of metal gates supported by air-filled rubber bladders. Compressors will inflate the bladders to approximately 25 psi to raise the gates. When stream flows are high enough, the bladders will deflate to lower the gates so water can flow over the top. The new, automated technology will be much more flexible and precise when managing the reservoir elevation.
What is the construction plan and timeline?
While the timeline is subject to change, the construction period is anticipated to be from July through October 2010. The new spillgates have been ordered and we expect delivery in July.
Once the new spillgates are delivered, we will remove some concrete from the top of the existing dam and replace it with new concrete to provide a good foundation to erect the new gates. A trough will be excavated in the dam crest for the compressed air lines that will be used to inflate the bladders.
The reservoir level must be lowered during construction to erect the new spillgates. During this period, the pool level will be 2 to 4 feet below the spillway crest, which may bring the level lower than what it has been in the past when the flashboards were erected each year in mid-summer. Construction should be complete and the reservoir level back to full pool by November of 2010.
How will the new spillway change Nine Mile operations?
No change in the full pool level is planned after the new spillway is installed. To the extent possible, we will maintain the reservoir level at the normal full pool elevation year around.
In the past the reservoir had to be lowered each summer to accommodate installation of the flashboards. When the flashboards were pulled in early winter or spring of each year, the material was lost and had to be replaced. Additionally, erecting the wooden flashboards each year is a labor intensive operation. The new spillway will result in less regular maintenance for Avista and enable the generation of additional power.
For project information, contact Steve Schultz, Project Manager, Senior Engineer. Apr 21 , 2010
We're always pleased when we can get out the word about safety on the bodies of water that our dams are connected with. Yesterday, KXLY reporter Jeff Humphrey did a good story on Avista raising the levels on Lake Coeur d'Alene in conjunction with low spring runoff.
If you're a recreational boater, that might mean you'll be able to use the lake earlier than in previous years. But with these early changes comes the dangers hidden under the water - such as rocks or wooden pilings, so watch out.
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