Thursday, March 10, 2016

High Tide in Downtown Olympia

Above: Areas of downtown Olympia experienced minor flooding due to a high tide in Budd Inlet and low atmospheric pressure early Thursday morning. Favorable weather conditions created a tide lower than expected, but still put some infrastructure under corrosive sea water. This view looking southwest was taken about 6:58 a.m. from Percival Landing behind the Oyster House restaurant near Sylvester Street. 

High Tide a Dry Run for Sea Level Rise

By Janine Gates

Starting at about 5:00 a.m., City of Olympia's Rich Hoey, director of public works, and Andy Haub, director of water resources, and staff were busy monitoring a potential 18 foot tide in Budd Inlet and flooding in downtown Olympia early Thursday morning.

Luckily, favorable weather conditions created a tide lower than expected, and flooding was relatively minor.

“It’s helpful that it’s not raining. It’s great for the crews to see how this works so they can get ready for the real thing...imagine six more inches on top of this....” said Haub, near the Oyster House restaurant on Sylvester Street at 6:46 a.m. 

Haub said the tide peaked at about 17.4 feet and the city had 17 people, a mix of stormwater operations and transportation staff, assisting in the field. 

Staff monitored the areas of 4th, 5th, and State Avenues between Columbia Street and the 4th Avenue bridge, Columbia Street between B and Corky Avenues by Budd Bay Cafe, and Thurston Avenue between Jefferson and Franklin Streets. 

There was no flooding on Water Street or at Capitol Lake as staff monitored the city’s stormwater shut off valve and pump located near the Waterstreet CafĂ©. 

Haub gets excited about atmospheric pressure dynamics and says he's going to look into putting a tide gauge near “The Kiss” statue on Percival Landing with an educational sign that explains how it all works.

“Tomorrow and future days look fine - barometric pressure is back up and tides are on the downward cycle,” said Haub on Thursday afternoon.

The Port of Olympia reported that it did not experience any backups or flooding. 

“Staff drove around and checked early this morning and have been on the property during the day,” said Port of Olympia communications and public affairs manager Kathleen White.

Two staff members of the LOTT Clean Water Alliance were seen out on bicycles checking for potential issues around or near the treatment plant and the Water Street pump station.  

“We did have some minimal overflow in the street in front of our building this morning, but nothing major. We have seen flooding there before….We haven’t had any problems with the treatment plant itself flooding as a result of these high tides. High tides combined with major storm events (do) put pressure on the outfall, causing our pumps to work harder than normal, said LOTT community relations and environmental policy director Kara Fowler.

Downtown Flooding - a Dry Run for Sea Level Rise

There are 112 known outfalls to Capitol Lake and Budd Inlet within the city limits. An outfall is the place where a river, drain, or sewer empties into the sea, a river, or a lake.

Of those piped outfalls, 36 are susceptible to backflow flooding. Twenty are city owned, nine around Capitol Lake are owned by Washington State, five are owned by the Port of Olympia, and two are privately owned, one near Bayview and one behind the Oyster House.

Above: Flooding creeps up Sylvester Street on Thursday morning looking south toward  the nine story Capital Center Building and the state Capitol Building. The Oyster House is on the left.

In January 2015, the city, Port of Olympia, and the LOTT Clean Water Alliance provided a coordinated presentation of their concerns and needs to a group of shoreline and coastal planners. Haub recently told Little Hollywood that his infrastructure needs, as he presented them to the group, remain valid:

Near-term Infrastructure (0.25 feet of sea level rise)
Install strategic tide gates, modify drainage system for the Capitol Lake to eliminate need to pump the 20 acre basin,  and investigate the permeability of downtown soils.

Medium-term Infrastructure (0.25 to 0.5 feet of sea level rise)
Modify elevations of Heritage Park, install permanent flood barriers on western shore of peninsula, consolidate peninsula drainage systems, disconnect flood-prone streets from the Moxlie Creek drainage system, and purchase pumps to handle downtown runoff during high tides.

After the sea level rise report presented to the city council on February 9, Little Hollywood asked Haub about Capitol Lake's stormwater system.  

“....As we learn more...we understand that the lake currently serves an important flood management function. However, the system and the topography around the lake could readily be altered to accommodate either a future estuary or lake. Sea rise will require change, regardless of the lake’s future....Our concern is that the long term projection for sea rise continues to increase, which will affect our infrastructure response.” 

He also said Percival Landing is about a foot too low to accommodate a very high tide or sea level rise.

“We expect the area around the southern portion of Percival Landing to over-top at 19 feet. The high tide on December 17, 2012 was a 17.6 foot tide. The estimate for a 100-year tide event under current conditions is 18 to 18.4 feet. When we rebuild it, we will need to evaluate the appropriate height and then how to incrementally increase it further as needed. That will be part of the design process. There are numerous options for combining flood barriers with public use and aesthetics…up to a point,” he said.

Above: By 7:10 a.m. Thursday morning, the tide was obviously receding, as indicated by this visible high water mark at Percival Landing.

For more photos and information and about downtown flooding, sea level rise, the Public Works report on sea level rise to city councilmembers on February 9, past high tide events, Capitol Lake, the valves that save a portion of downtown from flooding, the Oyster House, Percival Landing and more, go to Little Hollywood,, and type key words into the search engine.