The lagoon that meanders its way throughout Harbor Bay can be looked upon as the Community's backbone from which the rest of Harbor Bay emanates. It is the Community's key design feature that provides both residents and visitors not only a sense of natural beauty but also a feeling of tranquility. Great enjoyment is derived from watching the antics of the wildlife that call the lagoon its home.

While the lagoon's attributes provide us with great benefits, it must also be looked upon as a living organism with its own life cycle. Part of this life cycle involves the birth, growth and death of vegetation. The two most prolific plants that re-generate themselves in the lagoon are algae and widgeon grass. Both have incredibly fast growing cycles. Under the right conditions algae can double in size in less than 24 hours, widgeon grass even faster. The right conditions include an abundance of nutrients, clear water with a temperature higher than 65 degrees Fahrenheit and long sunny days. As the water warms above 65 degrees the growth becomes even faster.

These conditions annually occur between the months of April and June. The winter rains have come to an end. These rains have promoted the leaching of nutrients, primarily from fertilizers used in landscape maintenance, into the lagoon. The lagoon's functional purpose as the Community's central storm drain means that the water from all of the private property and streets ends up in the lagoon. This water runoff in turn brings the added yet unwanted nutrients.

With the end of the rains and winds, lagoon turbulence subsides causing sediment in the water to settle to the bottom of the lagoon. This in turn creates greater clarity through the water column. And, while this creates a more aesthetically pleasing lagoon, it also means that sunlight can more easily penetrate to the lagoon bottom, the beginning point of the vegetation's growth cycle.

The longer days with clear skies, intensifies the light patterns in the lagoon, which has the secondary effect of warming the lagoon's water. Thus, the perfect stage or medium is set for algae to begin to grow and grow rapidly.

The Community staff has maintained the lagoon since 1991 under the regulatory purview of the regional Water Quality Control Board. This Board is very concerned with improving the water quality of the San Francisco bay. Since our lagoon is directly linked to the bay via control gates, this Board regulates the means whereby the lagoon can be maintained. Prior to 1991 and outside company maintained the lagoon primarily by monthly abatement applications. While these applications killed off plant life, they did little to neither address the source of the plant life nor remove the dead material, which was left to decay in the lagoon. In addition, the chemical product used to control vegetation was removed from the market, leaving the Community staff to turn to the next level of somewhat more toxic products.

The convergence of these two actions moved the Community to adopt an integrated pest management policy. This policy means that the Community endeavors to reduce its reliance on chemicals to control unwanted vegetation in both the lagoon and landscape. Alternative methods were introduced and used to achieve the same control. In terms of the lagoon these include, weekly monitoring of the lagoon's vital characteristics such as water clarity, temperature, ph balance and oxygen content, more aggressive manual harvesting, introduction of aeration units, use of natural enzyme products, and, dredging of anaerobic material. In the past, the Community has experimented with the use of surface booms to keep surface debris in the lagoon's main current channel. Currently, the staff is looking at developing a program to use barley hay in the lagoon. This hay releases a natural algaecide.

All of the above techniques has resulted in the use of only one chemical abatement treatment for each of the last three years and only two treatments four years ago.

Unfortunately, staff cannot always predict the exact timing in which the climatic conditions will activate the vegetation growth cycle. This year is a case in point. In early May staff observed plant growth but in limited locations. It was believed that these could be controlled through spot or localized abatement. However, the climatic conditions changed very quickly and by the end of May, algae were growing quickly throughout the lagoon. This in turn required a full abatement treatment, followed by a flushing of the lagoon water into the bay. The treatment takes a minimum of three days to apply in order to prevent a rapid depletion of oxygen in the water column, thereby avoiding a large-scale kill of fish and shellfish. The lagoon must then be locked down for another four days to insure that the abatement treatment is effective. Following flushing, Community staff will undertake more aggressive manual harvesting to remove the remaining algae mats.

To bring the lagoon back to an alga controlled state takes a minimum of three, on average, four weeks. During this period, we will all experience floating mats of algae in various colors from bright green to black, depending upon their point in the plant's life cycle. Be assured that the Community staff is committed to maintaining the lagoon to the highest possible water quality standards. However, please do not forget that we are all living with a unique organic system with its own unique life cycle.

If you have any questions or concerns, please call Joe Landaeta, Director of Maintenance, at 865-3363 ext. 350 or e-mail JLandaeta@Harborbay.Org.