Beaver Lake: safe for swimming
Following water quality trends
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Beaver Lake Monitor
Volume 1, Issue 1 August, 1998
Beaver Lake Management District
Working to preserve Beaver Lake water quality
The Beaver Lake Management District advisory board has been meeting monthly since September 1996. We are a group of residents from within the Beaver Lake watershed that direct the District’s work program, which is aimed at protecting and improving the health of Beaver Lake. Current board members include Donna Carlson, Vicky Giannelli, Joe McConnell, Lisa Shank, Bob White, and Cory Wolfe.
So far, the District’s activities have focused on comprehensive monitoring of Beaver Lakes 1 and 2, ongoing stream monitoring (which includes runoff from Beaverdam and Trossach’s areas), inventorying the watershed’s wetlands, and developing a community education program. Beginning in the fall of 1998, inflow quality from the Norris property will be added to the stream monitoring program. We are also evaluating our options for more direct measurement of water quality performance for The Trossachs’ detention facility.
On October 11th, the board plans to host a watershed forum to solicit additional ideas on the management of Beaver Lake and kick-off the first annual Beaver Lake Stewardship Day (see related article page 4). We are also planning a watershed-wide planting event next spring to restore shoreline and watershed vegetation which will enhance water quality and increase wildlife habitat. For more information regarding the board’s activities, contact any board member.
Beaver Lake is safe for swimming
In response to recent concerns about high bacteria levels at area beaches, the Beaver Lake Management District (LMD) contracted with King County Department of Natural Resources to test the beach at Beaver Lake Park. Five samples were taken along the park’s shoreline with counts ranging from 2 to 29-coliforms/100 ml. The Seattle-King County Department of Public Health uses a threshold of 200-coliforms/100 ml for closing beaches. The Beaver Lake counts are well below that threshold. Citizens are still advised to take precautions against “swimmers itch” by briskly toweling off or taking a shower immediately after leaving the water.
Following water quality trends
An historical perspective
Lake surface water quality is monitored between May and October through King County’s citizen monitoring program. Data collected through this program is used to determine lake biological activity or trophic status using Robert Carlson’s (1977) numerical trophic state index (TSI). The index is based on the summer mean of three commonly measured lake parameters including Secchi depth (water clarity), total phosphorus (nutrient levels), and chlorophyll a (algae levels). Values between 40 and 50 indicate mesotrophic or good water quality conditions while those values greater than 50 indicate eutrophic or poorer water quality conditions.
Click here to see Figure 1 in greater detail
Figure 1 illustrates TSI values for Beaver Lake 2 where a twelve-year data record is available through the Volunteer Lake Monitoring Program. Between 1985 and 1989, the TSI ratings for Beaver Lake 2 ranged from 41.3 to 42.6 with an average of 42.1. During the past seven years (1991-1997), the trophic status value has ranged from 43.9 to 49.0 while averaging 46.2. The TSI data suggests that prior to the completion of the lake management plan in 1993, Beaver Lake 2 shifted several points within the mesotrophic range. The source for this small decline in water quality between the late 80’s and the present may be related to additional residential development of Beaver Lake’s shoreline and/or may be part of the natural water quality cycle for the lake. Both 1990 and 1991 were wet winters and may have provided additional nutrient loading to the lake pushing it into a slight more biologically productive cycle in the 90’s.
Click here to see Figure 2 in greater detail
It is important to note that since the lake management plan’s completion in 1993, lake water quality has remained stable. Higher surface concentration of both phosphorus and algae were observed during 1997 but are due to greater phosphorus input (Figure 2) during the record wet winters of 1996 and 1997 (Figure 3). The inflow water quality, monitored by the LMD, shows that inflow loading levels are significantly lower in 1998 (Figure 2) as compared to 1997 levels and are slightly lower then 1992 levels measured during the development of the lake management plan. Through the LMD, a watchful eye on water quality will continue to occur.
Click here to see Figure 3 in greater detail
Phosphorus is a naturally occurring, highly reactive element used in some explosive devices (e.g. fireworks, matches, and shells) as well as in making fertilizer, glass, and steel. In the aquatic world, phosphate is essential to fresh water plant growth — yet is generally the least abundant element that aquatic plants need.
Even small increases in phosphorus levels can cause plants and algae to grow to annoying levels, degrading water quality. Peoples’ actions add phosphate to lakes. Common sources include fertilizer, animal and human waste, detergents, and combustion of fossil fuels. Everyone in the watershed has a role in preserving the water quality of Beaver Lake. You can reduce phosphorus at the source by:
- Fertilizing your lawn and garden sparingly using organic fertilizer once or twice a year
- Be COOL and scoop up when walking your pet.
- Washing your car at a car wash or over a well drained area at home (e.g. grass or gravel) using a non-phosphate detergent.
- Avoiding use of chemicals that are harmful to the environment by carefully reading product labels.
If picnic shelter walls could talk!
Ruth Shearer tells the history of Beaver Lake County Park
n 1932, when the Beaver Lake area was just a brushy stump patch, Gus and Lulu Bartells leased the site of the present County Park from the Weyerhaeuser Logged Off Land Company and built rental cabins, a dance hall, and a larger Club Cabin for meetings. (The Club Cabin was recently renovated and is now the Issaquah Lodge in the County Park.) They also built another large building which was partially two-story, and lived in the upstairs part at first. The downstairs was a dining hall for large groups. Later, the Bartells bought more land from Weyerhaeuser and built a nice family home at the south end of Beaver Lake (now the Roberge home), and converted thir former upstairs living area to seperate dormitories for men and women, each accessed by a stairway from the dining room below.
Bartells’ resort was known as a great party place for groups of young people from Seattle. Some of the early settlers on Beaver lake discovered it by attending parties at Bartells. In the early 1950s, Dick (Andy) and Ruth Anderson took over operation of the resort and renamed it Andy’s Resort. Although records indicate the purchase was not completed until 1956, our Seattle church had an overnight outing in the dormitory of Andy’s Resort in the summer or fall of 1954. I remember vividly the beauty of the lake and the fun of beating all challengers on the outdoor ping pong table. By that time, new evergreen trees had grown to give ample shade for resort visitors.
In late 1960, Andersons sold the resort property for a Catholic youth camp and the dormitory building was converted to a chapel, which burned down shortly thereafter. Although the property was no longer open to the public, Camp Cabrini allowed the Beaver Lake Community Club to meet in their dining hall (the original dance hall, now converted to a picnic shelter). The camp was sold to King County in 1985, and is now Beaver Lake Park.
We learned the following from a Lake Sammamish Watershed Survey completed by King County in August 1997:
- 47 percent of lake front residents and 56 percent of watershed residents fertilize their lawns
- Two-thirds of Beaver Lake residents own at least one cat or dog. Yet only 35 percent of the population regularly scoop up when walking their pet
- Beaver Lake 1 is 13 acres in size with a maximum depth of 50 feet.
- Beaver Lake 2 is 62 acres in size with a maximum depth of 50 feet
- Beaver lake 3, known as Swamp Lake, is 4 acres in size.
- Beaver Lake 2 contains 82% of Beaver Lakes’ total volume.
*source: Beaver Lake Management Plan
‘Beaver Lake Stewardship Day’
Have problems with too many waterfowl? Want to learn how to enhance the water quality runoff from your property? Then mark your calendars for October 11 for the first annual Beaver Lake Stewardship Day, hosted by the Lake Management District. The day-long event at Beaver Lake Park will include developing a demonstration garden at the park, lectures by various garden experts, and native plant landscaping information.
The board is also looking for several lake front demonstration sites to participate in shoreline revegetation next spring. To get involved or help organize either event, please call Donna Carlson (557-8342) or Joe McConnell (391-0661).