Last update: 07/14/2009
Capitol Lake Management
Frequently asked questions about the future
Capitol Lake is a 260-acre man-made reservoir in Olympia and Tumwater, Washington. The Department of General Administration manages the lake as part of the Capitol Campus.
The lake was created in 1951 when the state constructed an earthen dam and concrete spillway at 5th Avenue in Olympia. The same year the state built Deschutes Parkway, a nearly two-mile long road that parallels the western shore of the lake.
The original idea for creating a lake came from the 1911 master plan for the design of the Legislative (Capitol) Building and the Capitol Campus. The plan called for the “submerging of the mud flats by the creation of an artificial lake through the construction of a dam, bulkhead or spillway near the Fourth Avenue Bridge.” The goal was to create a reflecting pool for the Capitol.
When the final approval was given for construction of the dam, following World War II, a new reason emerged for creating the lake. It would help revitalize a part of the community along the shores of Budd Inlet that was in a state of urban decay.
A committee made up of state, local and tribal government officials has been studying lake management issues for several years. The committee is expected to make a final recommendation on the future management of Capitol Lake to the director of General Administration in August 2009.
Q) Is there a problem with Capitol Lake?
A) Capitol Lake is a popular destination in Olympia because of its beauty and accessible trails. Large numbers of birds, salmon and bats use the lake, offering a unique opportunity for watching wildlife in an urban setting. The hillsides surrounding the area offer magnificent views of the lake, Puget Sound, the Olympic Mountains and Mount Rainier.
But Capitol Lake has some problems.
Every year more than 35,000 cubic yards of sediment comes down the Deschutes River and settles into the lake. That’s enough soil to cover a city block to a depth of three feet. Today, the lake is about 21 percent smaller and it holds roughly 60 percent less water than it did in 1951. Capitol Lake is turning into a marsh.
A shallow lake heats quickly in the summer. High water temperatures can stress fish and other aquatic species. Warm water also encourages the growth of aquatic weeds.
Capitol Lake does not meet water quality standards because of high levels of phosphorus, which causes algae blooms. When algae and weeds die in late summer, some of it washes out into Budd Inlet where it decomposes, using up oxygen essential for fish and other aquatic life.
The lake also has high levels of fecal coliform bacteria, which can pose a health risk if ingested. The bacterium is washed into the lake through the stormwater system.
Non-native weeds, such as Eurasian milfoil, are found in the lake and along the shoreline. These weeds crowd out native vegetation, reducing fish and wildlife habitat.
Before Capitol Lake was created, this area was an estuary, where freshwater from the Deschutes River mixed with the saltwater of Budd Inlet, part of Puget Sound. At the time the lake was created, the existing estuary had water quality problems and had been greatly modified by urbanization.
Q) What is an estuary?
A) It is an area where freshwater from a river mixes with the saltwater of the ocean. An estuary is influenced by tides but protected from large waves. Generally, estuaries are among the most productive habitats on earth, according to the Environmental Protection Agency. Estuaries also provide flood control and filter out pollutants. For more information see Information about Estuaries on the U.S. Environmental Protection Agency's website.
Q) Will an estuary solve problems affecting Capitol Lake?
A) An estuary will help with some problems, but not all. A Department of Ecology water quality study indicates that oxygen levels in Budd Inlet, which are low, would improve if Capitol Lake were converted to an estuary. Re-introducing saltwater would reduce the growth of non-native weeds. And hatchery salmon released into the lake each year would have a higher survival rate if there was an estuary.
But an estuary will not reduce the amount of nutrients, phosphorus and nitrogen, entering the watershed. The nutrients occur naturally, but high levels are caused by runoff from loggings sites, farms, failing septic systems, lawn fertilizer, pet waste and wastewater treatment facilities. These nutrients will continue to cause water quality problems in Puget Sound, even with estuary restoration.
And stormwater will continue to wash oil and other pollutants from roads and parking lots into Puget Sound.
Q) Can an estuary by restored by keeping the Capitol Lake Dam open?
A) No. Deschutes Parkway and other infrastructure around the lake were not built to withstand tidal action. Also, it isn’t possible to move the large volume of water that is part of a high tide through the narrow opening – 85 feet – at the dam. The original Deschutes estuary opening, before European settlement, was estimated to be about 2,000 feet wide. Estuary restoration will require construction a new 5th Avenue Bridge with a 500 foot opening.
Q) Which habitat would be better for fish and wildlife?
A) An estuary would provide habitat for species that depend on saltwater or brackish water, while a lake provides habitat for freshwater species. Some species use both habitats, preferring the one that provides the most food and protection from predators.
For example, an estuary would benefit salmon, crabs and some types of ducks, but there would be fewer bats, swallows and other types of ducks.
The Department of Fish and Wildlife says that there is uncertainty about how some species would respond to either option because of the lack of studies done on the lake.
Q) Is Capitol Lake polluted?
A) The lake has some water quality problems, but it is not contaminated with industrial pollutants or toxic chemicals. The Thurston County Environmental Health Division monitors the lake from May through October and reports that oxygen levels in the water are normal throughout most of the year, but can be higher than normal during brief periods in the summer. The agency also says there have been no toxic algae blooms in the lake.
The lake is off limits to swimming because of fecal coliform bacteria. The water is murky because of the sediment and algae. Much of the litter found along the lake’s shoreline comes from upstream.
Q) Would an estuary cause odor problems?
A) A restored Deschutes River estuary would probably smell like any other area adjacent to Puget Sound. The unpleasant odors reportedly coming from this area in the early part of the 20th century, as noted in some historical accounts, may have been due to the discharge of raw sewage. Wastewater is now treated before it goes into Puget Sound.
Q) What about mosquitoes?
A) Most species of mosquitoes breed in freshwater, not saltwater. A restored Deschutes estuary would likely produce far fewer of these insects than Capitol Lake does. In fact, it is the large number of mosquitoes and other aquatic insects that hatch from the lake that draws thousands of bats, swallows and swifts to feed on them.
Q) Who is on the committee that is looking at this issue?
A) The future of Capitol Lake is being studied by the Capitol Lake Adaptive Management Plan (CLAMP) Steering Committee. The committee consists of representatives from the Squaxin Island Tribe; the cities of Olympia and Tumwater; Thurston County; the Port of Olympia; and the departments of Fish and Wildlife, Natural Resources, Ecology and General Administration.
The committee is considering four alternatives for the future of Capitol Lake. The alternatives are:
- Status quo – Do not dredge the lake and continue current dam operations, weed control and other maintenance procedures.
- Managed lake – Conduct a large initial dredge to restore the depth of the lake and then periodically dredge the new sediment coming down the river.
- Estuary – Restore tidal action by dredging sediment; removing the dam and constructing a new 5th Avenue Bridge.
- Dual basin estuary – Same as the Estuary alternative but with a barrier dividing the north part of the lake into a saltwater reflecting pool adjacent to Heritage Park, and an estuary adjacent to Deschutes Parkway.
Q) How much would these options cost?
A) The cost estimate for restoring the estuary ranges from a $75 million to $90 million. This preliminary cost estimate includes:
- Dredging Capitol Lake prior to dam removal
- Removing the dam
- Building a new 5th Avenue bridge
- Reinforcing Deschutes Parkway
- Other infrastructure improvements
Restoring the lake by dredging it is estimated to cost between $79 million to $154 million. Dredging the lake to make it deeper would reduce some of the environmental problems.
Dredging for an estuary would cost less than restoring the lake depth because some sediment would be relocated to the shoreline, to reinforce Deschutes Parkway. The sediment dredged from the lake would have to be transported to another location because it is contaminated with Purple loosestrife seeds, a non-native weed.
Q) Who makes the final decision about the future of Capitol Lake?
A) Ultimately, the Legislature will decide whether to pay for any changes to Capitol Lake.
The CLAMP committee will make a recommendation to Linda Bremer, General Administration director, in August 2009.
Bremer will consider all of the information and studies that have gone into this effort before taking a recommendation to the State Capitol Committee. This committee must approve the use of all state-owned real estate in Thurston County, which includes Capitol Lake. The State Capitol Committee members are the Commissioner of Public Lands, the Secretary of State, the Lieutenant Governor and the Governor.
Director Bremer will work closely with Gov. Chris Gregoire on this issue.
Q) Will the public have an opportunity to be involved in the decision process?
A) Yes. General Administration is seeking public input. There are several opportunities to comment. These include:
- Email: Write to capitol.lake@ga.wa.gov
- Online: Go to the General Administration Web site www.ga.wa.gov. Click on the “feedback” link at the bottom of the page. Under the subject field, select “Capitol Lake.” Comments are being taken now.
- Public Workshop on Wednesday, June 24 – Technical staff will be on hand to answer questions. There will be two brief orientations describing how the workshop works and on how to provide a written comment.
- Monthly CLAMP meetings – The Capitol Lake Adaptive Management Plan Steering Committee meets monthly. There is a public comment period during these meetings. The schedule is available on the Capitol Lake main page.
For more information
Jim Erskine, GA Communications Office
(360) 902-7206, jerskin@ga.wa.gov
Nathaniel Jones, GA Facilities Division
(360) 902-0944, 4, njones@ga.wa.gov
