Leaving a Lake Legacy - A District Park Planning Seminar

Neighborhood Parks Council Presents
Leaving a Lake Legacy - A District Park Planning Seminar
with Kathleen Pilat, Hydrologist, NPC

Download the PDF: Leaving a Lake Legacy, a paper by Kathleen Pilat

*Note: the PDF does not include graphics. If you would like a copy of the complete paper, please request a hardcopy from NPC.

Katie Pilat, NPC, presenting her study		Linda Hunter, NPC, and Dr. Alex Horne
Slideshow presentation
Dylan Hayes
Isabel Wade, NPC, with all of the seminar panelists

Leaving a Lake Legacy Minutes:

54 people in attendance

Welcome Address Linda Hunter, Neighborhood Parks Council

Native Americans were not passive stewards of the land. They conducted controlled burns and propagated plants. The Ohlone were water loving people. They lived near rivers and close to the shores of our bay, lakes, and ocean. Over 10,000 Ohlone were supported by our city’s natural resources.

Just 233 years ago, San Francisco Bay was deeper and contained much more fresh water. Ohlone people were able to find drinking water on Angel Island. Great changes occurred with the arrival of European explorers and settler. The salinity of San Francisco Bay’s water has increased with diversion of freshwater to support people and agriculture. San Francisco’s creeks run through culverts underground. Our wetlands have been claimed by concrete. We have three natural lakes left. We can never bring these back to their original state, but we can help them to be self-sustaining and to remain viable. We are the stewards of the land now. We should take this seriously and be aware and active.

The Neighborhood Parks Council would like to give special thanks to the Gaia Fund for making this project possible.

The Lakes

Mountain Lake: Dr. Alex Horne, Dr. Horne is a UC Berkeley Civil and Environmental Engineer and Limnologist and studied Mountain Lake

Mountain Lake was assessed using the classic 5 methods of watershed management and the 17 methods of in-lake restoration. From this process, a few applicable methods were proposed for implementation. It would be a good idea to carry out the same processes at the other 2 natural lakes in San Francisco. Ecological Engineering, the sustainable form of environmental engineering could assist in the restoration and enhancement of these areas. In particular, the use of constructed wetlands to remove pollutants while providing new wildlife habitat and the use of solar and wind power to provide the energy needed for oxygenation should be considered.

A summary of the condition of the natural lakes of San Francisco:

• Mountain Lake suffers from deliberate sedimentation and toxic contamination from roadway run-off.
• Mountain Lake, Lake Merced, and Pine Lake are plagued with eutrophication, an overgrowth of algae caused by overloads of minerals or organic materials such as leaves or fertilizer.
• Pine Lake and Lake Merced suffer from lack of water.

What Can Be Done?

• Remove sediment to clean up contaminants and restore depth.
• Water shortages can be helped with careful reuse of water to minimize pumping of water from the aquifer and lakes.
• Add oxygen to water to counteract depletions caused by algae blooms. This will prevent fish die-off and smelly water.

Renewing Mountain Lake

Mountain Lake was probably formed a few thousand years ago by wind erosion in the sand dunes. It was used as a drinking water source. Spanish Missionaries first described the lake about 250 years ago. Since then, approximately seven feet of sediment has been deposited and over two acres filled in, mostly during the building of Park Presidio Boulevard in the 1930's. Though inflow has not changed much between 1776 and 1997, Mountain Lake's volume has been decreased by half, surface area by a third. The historical depth of the lake is about 30 feet. The Lake covers between 2 and 3 acres and is shallow, with an average depth of 3 to 5 feet and a maximum depth of about nine feet. A shallow lake is prone to growth of algae and vegetation.

Most likely, without intervention, Mountain Lake will soon be a marsh. We want to maximize open water. Deep lakes, those with a depth of 30 to 40 feet, have two layers of water. The top layer is warmer, receives light and will support algae growth. The lower layer is darker, cooler and holds nutrients. A shallow lake mixes nutrients, algae, and light in one layer -- a recipe for algae blooms.

Nutrients from the Presidio Golf Course run-off do cause algae blooms and fish kills, though studies show that it is not a huge problem. About a third of the nutrients from fertilizer gets into the water. Algae serves as a source of food and oxygen when alive, but if excessive algae grows, it chokes itself out and causes cloudy, sometimes putrid, water. When it dies off, oxygen is depleted from the lake. Fish are unable to breathe and they soon die, too.

Contamination is an issue, too. Run-off from Park Presidio Boulevard is the major contributor. Most of the toxins are buried under the upper layer of silt. Some of you may remember the swans that had lead poisoning a few years ago.

In 1995, the Greening of the Presidio workshop offered some potential solutions:

• Do nothing. The Lake looks okay as it is, but it is unstable.
• Upgrade. Remove one meter of recently contaminated sediment.
• Restore the lake's original depth by dredging.
• Enhance the lake. This may require some dredging. This is my personal favorite. We can't go back to the old days, but we can help the lake be a more functional system.

Ecology and Management of Lakes

Control eutrophication by controlling the watershed (outside) or the lake (inside).

Outside the Lakes:

• Collect and treat sewage. This is not really a problem at San Francisco's Lakes.
• Decrease landscape and agricultural fertilizer input.
• Block entry of storm run-off and sediment out particles.
• Use wetlands to filter inflow -- a "biological filter".

Inside the Lake:

• Make physical, chemical, or biological changes. Bio-manipulation is one form of a biological management technique. Controlling the food web from the top by adding algae eating fish is a method of bio-manipulation. These are probably the best long term sustainable methods.

Can the Lake be Fixed?

The following actions can help:

• Dredge the lake's bottom to deepen it and remove contaminated sediment.
• Maximize open water. Get rid of the swamp.
• Relocate wetlands upstream to catch nutrient rich run-off from the golf course.
• Install a solar powered oxygenator to increase habitat value and prevent smells. In deep water, oxygen prevents wetland plants from growing.
• Remove overhanging trees to allow the wetlands plants to grow and prevent browning of water.

Actions performed so far:

• Some Eucalyptus have been removed from the lakeshore.
• Lead found in dredge spoils is delaying dredging. Now, it may not happen at all.
• Some oxygen has been added. The old fish farms have been removed.

Recycled Wastewater

Definition: Tertiary treated wastewater: Oxidized, filtered and disinfected, then added to wetlands that drain into the lake.

• Recycled wastewater could be added to the lake and water the golf course. Under California law, potable water can't be used. We have the technology to return the lake to a self-sustaining state; we just need the will.

Pine Lake: Dylan Hayes, Friends of Stern Grove/Pine Lake Park

Pine Lake is an urban oasis. Recently, 35 types of native plants and 65 species of birds were counted in a single day. I grew up near the park and have enjoyed it since my childhood. It is hard to see the resemblance between then and now.

The watershed used to cover about 700 acres, stretching up to Edgehill and Mount Davidson and collecting the run-off of creeks and springs. The watershed is now 35 acres and the lake itself has lost about a third of its surface area. Storm water no longer reaches the lake, so it is down to the water table level. The lake is fed by the Lake Merced aquifer. The lake faces problems due to low water level, denuded banks, die-off of riparian vegetation, heavy unmanaged use of paths, occasional sewage run-off, sedimentation, eutrophication, the presence of hazardous trees and introduced primrose.

Pine Lake was part of San Francisco's extensive dunes systems. The Spanish called the Lake "Laguna Puerca" because of the wild boars that could be found nearby. In 1847, the Greene Family homesteaded the area. In 1871, the Greene's planted the first Eucalyptus trees on the lake's banks. In the early days, the city's elite used the park, but by the late 1890's they had retreated. Mrs. Stern later bought the property and in 1931, deeded it to the city in honor of her husband, Sigmund. The clubhouse was built in 1938 and a third of Pine Lake was filled in. The aquatic Primrose was introduced in 1995. After storms caused sewage to overflow into the lake, it gained a stronghold became very invasive. As recently as the 1980's, the water level nearly reached the sidewalk ringing the lake.

The Department of Public Works and Recreation and Parks Department plan to increase the water levels 4 to 4.5 feet to about 11 feet. Pine Lake needs open water and restoration. Lincoln High School has been helping and using the area as an outdoor classroom. We are continuing stewardship and see signs of hope. Please help respect and preserve this functioning system.

Lake Merced: John Plummer, Founder of Friends of Lake Merced and webmaster at www.lakemerced.org

The Short and Sad Story of Lake Merced

Lake Merced Park encompasses 600 acres. Harding Park Golf Course, Lake Merced itself, and the peripheral open space are about 200 acres each. The lake is an expression of the Westside Basin/Golden Gate Aquifer that covers 25,000 acres. The Basin reaches Golden Gate Park on the north, the San Francisco airport on the southeast, and the San Andreas Fault on the west. Each year, we receive approximately 40,000 acre-feet of water in the form of rainfall, and 40,000 acre-feet of water is pumped from the aquifer. If we could capture our rainfall and recycle 25%, we could supply 10,000 acre-feet of water without touching the aquifer or Hetch Hetchy. San Francisco is the only urban California County without a recycled water program. We had one and gave it up.

Water levels are down and on average, we have lost a foot per year. This decline was accelerated during the drought of 1982-1987. The problems are simple:

• The aquifer is being depleted more quickly than it is replenished.
• Urbanization and development, building of wells, and pumping have changed the flow of groundwater.
• The solution lies in restoring and maintaining the aquifer. Too many demands are made on our groundwater.

A sewer crosses Lake Merced right at San Bruno Fault, one of the prime spots for liquefaction to occur. In an earthquake, there will be no question about water quality at Lake Merced.

The area is of important economic and recreational value to the city. There are a large number of golf courses, the San Francisco Zoo, the Recreational Center for the Handicapped, for a Girl Scout Camp, high-density housing, San Francisco State University, Lowell High School, and an Elementary School. The park is well used, with activities like rowing, biking and walking the 4.4-mile circuitous path, picnics, and just watching the beautiful scenery.

Not so long ago, Lake Merced was a heavily fished deep lake. Now, as we look at the lake, we see that many piers and boat hoists no longer touch the water's edge. The lake is turning into a wetland, choked with algae and lined with tule grass. This change is attracting new species, but not supporting many of the area's historical plants and animals. Lake Merced is an important part of the Pacific Flyway, being the largest body of freshwater between Point Reyes and Pescadero.

Please come visit Lake Merced and help us preserve and enjoy it.

NPC Hydrology Project - Background and Solutions: Katie Pilat, Hydrologist

The Neighborhood Parks Council decided to get involved because our Lakes are located in some of the most important parks in the city, and are great ecological and recreational treasures. Thanks for coming out and thinking about our lakes.

Questions:

• Are San Francisco's lakes in peril? If so, are the causes primarily human activity or natural phenomena?
• What kind of monitoring is occurring?
• How effective are the protections we have in place?

Historically, lakes and creeks dotted the landscape. Islais Creek started in Glen Canyon and flowed to the Bay. Mission, Dolores, and Hayes Creeks flowed into the marshes of Mission Bay. The Spanish Mission Dolores was purposely sited near the freshwater of Dolores Lagoon. Lobos Creek still courses through the Presidio to Baker Beach. Part of the inflow to Pine Lake and Lake Merced came from creeks.

In a few places, we can still find evidence of our underground creeks. Many Civic Center buildings must constantly pump out their basements to keep them dry. The Fountain at Civic Center and Market Street is filled not with city water, but with Hayes Creek water pumped from underground.

Today, we have three lakes left. Here are the lakes and the issues they face:

Mountain Lake

• Contamination from Park Presidio Boulevard
• Sedimentation occurring at four times the historical rate
• Algae blooms and fish kills (eutrophication) caused by excessive nutrients (such as from fertilizer in golf course and park runoff)

Pine Lake

• Water level is down
• Invasive primrose has taken over the west end of the lake which has historically been open water.
• Slope erosion and sedimentation
• Aquifer is not being adequately replenished

Lake Merced

• Water level is down
• Aquifer is not being adequately replenished

All three lakes are expressions of an aquifer where the ground surface dips below the aquifer. San Francisco has seven different ground water basins. Lake Merced and Pine Lake are facing decreased water levels because of water pumping and urbanization affecting recharging of the aquifer. On the other hand, there is a greater recharge of Mountain Lake's aquifer and almost no pumping.

San Francisco's lakes have been degraded. The effects of urbanization are far reaching and will be long lasting. There is no reason to expect natural revitalization.

Future Plans

Since 1999, work has been occurring at Mountain Lake under the Enhancement Plan. Enhancement Plans for Pine Lake and Lake Merced call for long and short term remedial actions, but so far, nothing has happened. The plans include:

• Reducing aquifer pumping in two to eight years. Daly City has a fifty-year agreement with the golf courses to use tertiary treated waste water for a minimum of 70% of their water needs. The water treatment plant should be completed in 2004.
• The Public Utilities Commission has included a water recycling program plan in their Capital Improvement Program, primarily for irrigation, but also in new developments.
• San Francisco and Daly City are planning a conjunctive use agreement where Daly City will reduce pumping by up to 80% if Hetch Hetchy water is available.
• The Vista Grande Canal storm water diversion project is in the works to bring water to Lake Merced.
• In the short term, there are discussions about adding Hetch-Hetchy water to the lake. This is not a certain or permanent solution, though. The lake will eventually adjust itself back to the same level as the aquifer. A community meeting will happen in July.

What Else Could Help?

Aquifer Rehabilitation -

• Put more water in, take less out
• Conserve
• Use recycled water
• "Conjunctive use", the use of a combination of surface and ground water based on availability.
• Recharge groundwater

San Jose, Palo Alto, and Livermore all use recycled water for irrigation, and Marin also uses it for car washes, toilet flushing, and commercial laundering. Twenty percent of water use in Irvine, California, is recycled water.

According to the PUC, the Westside Basin aquifer is currently being recharged at a reduce rate compared to historical recharge. Even if we were to stop pumping now, we won't see improvements to the lakes for decades. Here in San Francisco, we average about twenty inches, or 16 billion gallons, of rainfall per year. We could be using this natural resource to recharge the aquifer. Instead, most rainfall goes into the sewer system and is carried to one of the wastewater treatment plants where it is treated and released into the ocean or bay. There are a few ways to direct rainfall to the aquifer.

• Disconnect rooftops from the sewer flow. Rainfall from rooftops is much cleaner than road run-off. It can be directed to a dry well or allowed to seep into the ground. The "Tree People" organization in Los Angeles uses this method to prevent flooding of buildings. The PUC will be retrofitting the roofs of a few hundred houses in the Western Aquifer area. This is mainly to prevent combined sewer overflow, but will also help the aquifer.
• Use permeable or pervious pavements that allow more water into the ground. This could be used for parking lots, roads and parking lanes.
• Reconnect watersheds and collect run-off, like the Vista Grande Canal. Because of urbanization, about 95% of the lakes' watersheds are disconnected.
• Restore our creeks. This is an ideal way to direct water to our lakes. The Presidio's Tennessee Hollow Creek is perfect for this. Sections of Islais and Precita Creeks run under schoolyards and parks.

The Ohlone people lived in villages clustered around the Bay Area's productive waters. Thriving waterways were their legacy. Modern society has given us a legacy of skyscrapers, highways, sidewalks, and subways. In doing this, they filled and destroyed much of our natural heritage. Will we let this continue? Or will we choose to preserve and revitalize out three natural lakes? If our children's children are able to see improvement, it is worth it to start investing now. If we improve, even incrementally during maintenance, we can start a positive trend.

Mountain Lake Enhancement Plan: Brian Hildebidle, Restoration Coordinator at Mountain Lake for the Golden Gate National Parks Association

The Enhancement Plan is a project partnership between the Golden Gate National Parks Association, the National Park Service, and the Presidio Trust. The Presidio Trust manages work at the lake. Funding for this project came from mitigation funds from building runways at SFO. The Friends of Mountain Lake have been instrumental in this project.

Mountain Lake

• Supplied water for the Army
• Was filled during construction of Park Presidio Boulevard.
• Was the source of irrigation water for the Presidio Golf Course.
• Is a dumping ground for unwanted aquatic pets, such as the alligator from a few years ago.
• Is a planting site for non-native vegetation

The Enhancement Plan

• There will be a buffer planting between the lake and the road.
• Dredging and aeration are planned, but being delayed by negotiations between the Presidio Trust and the State of California.
• Interpretive trails and overlooks will be included.
• Tree removal and revegetation will occur, mostly on the Eastern shore.
• Reduce the amount of sediment in the lake.
• Replace Eucalyptus trees with native trees. This will decrease the amount of humic acid into the water.
• Provide wildlife habitat.

Planning and Implementation

• Conduct studies of flora and fauna
• Propagation from Presidio parents and planting of native plants.
• Erosion control with use of jute netting, straw mulch and straw wattles.
• A fence was erected to control damage to plantings. There was a fire on May 7th of this year. About a third of an acre was burned. Approximately 1500 plants were damaged. There is good news, though. We're already seeing some re-sprouts.
• More weeding and restoration.

Presidio Recycled Water Project: Patrick Johnston, Kennedy/Jenks and WateReuse

The Water Reuse project is a partnership between Presidio Trust, Kennedy/Jenks. The treatment plant will produce disinfected tertiary water, the highest level of recycled water available.

Project History

The Letterman complex was slated for redevelopment. The CCSF Southeast wastewater treatment plant has long experienced overflow problems during winter storms. The Presidio's sanitary sewers need to be rehabilitated and re-lined. We were looking for a reduction of wastewater flows.

To make this project work, we needed both producers and consumers of wastewater/recycled water. We have producers now, and are looking at increases due to more commercial use of the Presidio. The largest consumer of water is the Presidio golf course. Unfortunately, it can't take part in this project because of possible pollution of Lobos Creek, which is the source of potable water in Presidio. Green spaces will be users of about 500,000 gallons during dry season. Currently, Presidio workers, residents, and visitors produce about 200,000 gallons wastewater per day, but this will probably increase to 600,000 gallons per day within 10 years.

Economics

• Capital costs
• Operating and Maintenance costs
• Wastewater treatment fees. The Presidio currently pays San Francisco to treat its wastewater.
• This project will probably pay for itself in about 30 years.

Conclusion

• We can use an existing resource
• Drought proof
• Environmentally sound
• Relieves pressure on existing potable water sources
• Help San Francisco's wastewater treatment problems.

Keep track of this exciting project as we move into the design phase.

Creek Daylighting Projects: Carole Schemmerling, Co-Founder of the Urban Creeks Council

Interest in daylighting and restoring some of San Francisco's creeks is on the rise. I'll tell you about some of our successful projects in Berkeley.

We founded the Urban Creeks Council in 1982 to restore, preserve, and enhance riparian systems, especially in urban settings. I was working for Berkeley's Parks Department when Berkeley passed a $5million/5 year bond measure to put parks in neighborhoods with none. We found a low-income neighborhood that had old, abandoned railroad tracks and enough space for a park. The site was just collecting trash at this point. We found out that Strawberry Creek had run through the site until 1912, when in was put into an underground culvert. This sparked an idea.

City staff was extremely reluctant to re-open the creek. They thought people would get hurt or die. We managed to convince the Berkeley Parks Commission that they would be derelict in their duty as stewards of nature and recreation if they didn't back this project. We held public hearings and the idea passed through the Parks Commission and City Council.

For the first time creek, a creek was daylighted from a culvert in California. The designer was a landscape architect for the city of Berkeley. He'd never worked with creeks before. In order to stay within the budget, he didn't remove the concrete or soil from the site. These materials were reused. There was no template to follow, so the designer used the meandering lines he saw in the soil from coal dust deposited when the creek was still open as a guide. We were hoping for heavy rains to make the creek overflow, so we could see how the floodplains would work. It took twelve years for that to happen. So far, it has worked beautifully.

Flood terraces were used only once, in 1997 during extremely heavy rains. We recommend creating flood plains whenever possible. Innovative open swales are able to move water off-site much more quickly than pipes. Using swales instead of underground viaducts saved money, too. Dirt from digging was used to separate the park from busy roads nearby, so the park was more child-friendly. A playground and hard-surface courts were installed near housing.

The park achieved instant success and won the "California Cities" award as well as numerous design and Landscape Architecture awards. The park is low maintenance. At 4.5 acres, the park is not very large. The City and Parks declined to maintain it, though. So, we started our own maintenance crew. We trained ten to twelve neighborhood youth to take care of the park and started with a $40,000 per year contract. Now, it has developed into a $90,000 per year program that maintains four Berkeley parks. Some of our former trainees have gone on to attend UC Berkeley's Urban Planning program.

The vegetation has matured and grown since we planted it. The whole neighborhood has been affected by the presence of this park. People use it as a gathering place. A bakery and design center have moved into a building located next to park. Studies in California and Colorado show that properties located near a natural stream increases value ten to twenty percent. Creeks are considered amenities.

Next Project

A school was declared seismically unsafe. It was decided that the building would be demolished and a new school would be built. The PTA wanted to open a creek that was put underground in the 1960's. They contacted us. We conducted an extensive community planning process. The Urban Creeks Council, the PTA, and community members worked with local Conservation Corps and Americorps teams on the restoration. The Corps are great resources. They provide low cost labor and often stay involved with the projects they've worked on. The school's science teachers had their students help and learn in this "living laboratory". The kids became creek experts.

Bioengineering

Coir netting was installed on creekside and "nailed in place" with native plants. Willows are especially good for this purpose. We mulched and installed many container plants. The project looked great within months and immediately became a home to many species of plants and birds.

We are willing to work in any community that asks and will take ownership in the process. We helped a community that had problems with overflowing storm drains that continually flooded homes downstream. The Urban Creeks Council helped secure funding, conduct outreach, and design the project. The daylighted creek featured pools & riffles to slow down the water. Willows and natives were planted. Now, the creek is home to colony of Black Phoebes. Flooding is not an issue, anymore.

Creeks evolve over time. From "daylighting" to maturity is generally a ten to twelve year process. One of the interesting "complaints" we hear about maturing creeks is that neighbors can't see the water itself through all of the vegetation. The possibilities to open streams are out there. We are trying to open Strawberry Creek in downtown Berkeley. These projects often revitalize neighborhoods. Its nice to think that even in dense urban areas you can restore a bit of nature.

Conclusion: Linda Hunter, NPC

Lakes are important environmental archives. The Ohlone prospered on San Francisco's landscape for 3000 years. They allowed our lakes and creeks to thrive. With European arrival, the rate of infilling dramatically increased. What will future generations see? Will our legacy be skyscrapers, houses, and highways? We all make that decision.

What You Can Do

• Call your District Supervisors and let them know you care about these issues.
• Look at your own house for solutions. Find ways that you can help undo the damage. Minimize concrete use in your yard. Call the PUC and volunteer to be part of the PUC stormwater retrofit project.
• Restore and daylight creeks that deliver water to the Lakes. Islais Creek and the Presidio's Tennessee Hollow are possible daylighting projects.
• Be informed. Understand the consequences of paving, using ground water.
• Volunteer! Help with restoration or by getting the word out.
• Visit your Lakes. See why they're worth saving!

Katie Pilat's paper will be published in 4 to 6 weeks. The Mayor, Board of Supervisors, Public Utilities Commission and the NPC Board of Directors will all receive copies. Contact the Neighborhood Parks Council to receive your copy.

Question and Answer Forum

Pine Lake is to be raised 4 to 4.5 feet? Who authorized this?

• That is part of the DPW and RPD parks enhancement plan.

In the diagram of Mountain Lake, there is a buffer strip. What will it be made of?

• Native trees, like Alders and Bay Laurel will be planted between the Lake and Park Presidio Boulevard. Some of the Eucalyptus trees that are too dangerous to cut will be left in place. Unfortunately, this won't reduce noise as much as a sound wall.

How much will the water treatment plant cost?

• The building will cost $9 million.

What will be the effects of dredging be at Mountain Lake?

• Dredging should increase diversity at the lake by increasing habitat diversity. It shouldn't disturb wildlife much while happening.

What is delaying the dredging project?

• Negotiation of funding is the issue.