Keuka Lake Book
Keuka Lake offers residents and visitors beautiful scenery, clear blue waters, outstanding fishing, and an excellent lake for water sports. Much of the lake development occurred during the 1940s and 50s, when there was less understanding about the effects of development on lake water quality. Building along Keuka Lake has continued since then and today there are around 2900 seasonal and year-round lakeside residences.
High building densities, construction on marginal lands and greater numbers of aging septic systems risk overwhelming Keuka Lake's natural ability to cleans itself. In an effort to protect public health, safety, and to address potential environmental impacts that building and altering the landscape might have, the municipalities around Keuka have adopted regulations that govern design and construction in and around the lake. Zoning ordinances provide guidance for site development including the type and location of septic systems, building distance from the shore or neighboring buildings, maximum building height, etc... . Ordinances vary from town to town, so it is important to check with your Code Enforcement Officer for the specific regulations in your town. They will also know which other agencies it will be necessary to contact before building. Depending on the condition of your building site and proposed project, it may be necessary to obtain construction permits from the town, state, or even federal agencies.
Any excavation at or below the mean high water level (MHWL), 715.30 ft above mean sea level for Keuka Lake, requires a permit from the New York State Department of Conservation (DEC). An example would be the construction of a dock anchored to shore by a breakwall. A DEC and local permit would be required for the breakwall and possibly a separate local permit would be necessary for the dock. If you have any doubts about whether or not a permit is needed for a project, call your local CEO and/or the DEC. It is always better to discover a permit is not needed rather than being cited for a violation.
Municipalities in NYS use local laws to protect public health, safety, welfare and the environment. Protection of water quality of Keuka Lake is important to the 2900 lake residences and the 10,000 people from the Villages of Dresden, Hammondsport, and Penn Yan and Keuka Park. These laws also help preserve the clarity of the water, scenic views, fisheries, and many of the other reasons people are drawn to the lake. Everyone on and around the lake is part of a community, and each individual has an impact.
The next three sections provide information on shoreline development: residences, docks, and beach erosion protection. The fourth section provides important information on lake levels and flooding that should be taken into account before any construction.
Sediment Control for Building and Property Improvements
The largest negative impact that construction can have on the lake is increased sedimentation due to increased runoff over disturbed soils. Sediments in the lake can muddy the water, smother fish eggs, increase cost of water filtration and bring in nutrients that cause undesirable algae blooms. Simple erosion control practices can reduce the amount of soil reaching the water by reducing the amount and velocity of water washing downhill.
Before the project begins
A little forethought and understanding of how erosion prevention works will make sediment control easier. In nature, plant leaves and branches slow the impact of rain before it reaches the soil. Plant roots hold soil in place during storms and heavy snow melts and debris, grasses and underbrush slow overland flow, allowing water more time to infiltrate into the soil. When developing a lot, preserve as much soil, trees and plants as possible to minimize erosion. Deflecting "clean" water away from the construction site will also help to reduce erosion and can be accomplished with seeded and mulched swales (shallow diversion ditches) and dikes. The "clean" water should be directed into an area where it can slowly filter into the soil.
Temporary sediment barriers placed before construction areas can intercept and remove sediment from runoff once excavation begins. Straw bales firmly staked into the ground, across the slope, slows water flow which allows suspended particles to settle. A second option is a silt fence made of landscaping fabric, which can be used on steeper slopes. Both need to be checked after rainstorms to make sure they are working properly. Swales and dikes can be used to divert sediment-laden water to settling ponds or other sediment trapping devices. These are usually used on larger construction projects in conjunction with bales and fences.
Once erosion prevention and sediment control measures are in place, excavation and construction can begin.
During construction, save as much of the topsoil as possible. Stockpile it out of the way and protect it by covering or seeding. Replacing a layer of topsoil after construction provides a good base for replanting, reduces irrigation needs, and reduces the need for fertilizer.
Check the sediment control devices and adjust as necessary. As grades change during construction, the direction and force of runoff can change as well. This could make previous efforts for control ineffective.
Protect existing vegetation, including trees, from additional damage. Keep the area of impact contained in the smallest area reasonable. It often takes a year or more to reestablish vegetation on a construction site and many years to replace dead trees.
Stabilize the disturbed areas as soon as possible upon completion of the project. This can include replacing saved topsoil, seeding or planting and finally mulching. Placing mature sod is another option, although it is quite expensive. When selecting a seed mixture or other plants, consider whether the site is to be mowed, light and moisture conditions, and the steepness of the slope. Replanting native vegetation has the advantage that these plants have evolved in the area and are well suited for the conditions.
Mulch is used to stabilize the soil, provide moisture and nutrients for the seedlings, and prevent seeds and seedlings from washing away. Some examples of different types of mulches are: sawdust, woodchips/bark mulch, compost, hay or straw, peat moss, gravel or stone, and plastic. Each has its advantages and drawbacks. A local nursery, Cornell Cooperative Extension, or a landscape contractor can help you decide which materials are best for your project.
Once plants have established a sufficient root system to prevent erosion, the controls installed prior to construction can be removed. Sediment accumulated in basins and traps should be carefully disposed of to prevent it from washing down into the lake. Sometimes it is desirable to leave the erosion prevention dikes and/or swales in place permanently.
Before beginning any project, remember to contact the local CEO about local zoning ordinances and permits. Also, discuss erosion and sediment control measures with your contractor to make sure control measures will be installed.
Many lake residents desire a dock for easy access to the water, docking for boats, fishing access, and other forms of recreation. They can be permanent - anchored to the lake bed and left in place year-round; or temporary - a seasonal structure. Floating swimming platforms, ski jumps and other recreational platforms placed in the lake are regulated by the New York State Office of Parks and Recreation.
Two common dock designs are the floating and post-supported docks. Floating docks are decks supported by a buoyant materials such as clean, sealed plastic drums or rigid, plastic foam. The dock should be kept in place by chains attached to weights in the lake bed. Post-supported docks are held in place by posts vertically resting on or sunken into the lake bed. The narrow posts allow natural wave action and fish and other wildlife to pass freely around it.
Both of these structures have a minimal impact on the lake bottom during and after construction. In addition, they can be designed to be removable for the winter. Removal prevents ice damage which reduces the need for repair each spring. It also allows the dock to be maintained on land, reducing the amount of paint or sealer entering the lake. In exposed areas of the lake, the design and materials need to be robust and able to withstand strong winds and heavy wave action.
Pressure-treated wood is the most common and initially the most economical material for building docks. Salt injected into the wood during the pressure-treatment process preserves the wood from water damage, fungi, and insects. There are other types of pressure-treated wood impregnated with chemicals such as creosote, pentachlorophenol, or arsenic-based chemicals that should not be used in the lake. These chemicals are toxic to humans as well as the lake environment.
There are many alternatives to pressure-treated wood such as cedar and redwood which are naturally resistant to water immersion. Aluminum is a strong and light material that will last as a dock material. Polyvinylchloride (PVC) and recycled plastic also offer light weight with plenty of strength. These and other alternative building materials may initially be more expensive than pressure-treated wood, however, plastics and metals will last years longer and require less maintenance over time.
Floating docks and platforms are anchored to prevent them from blowing or washing away. Traditional anchors include concrete or stone-filled steel drums. Even if they appear perfectly clean, used drums often contain chemical residues potentially harmful to the lake. The same is true for using empty drums and barrels as floats. If these types of containers are used, buy them new or make sure that the previous contents were not toxic.
Remember: before constructing a dock, mooring or other shoreline structure, consult the code enforcement officer and other potential regulating agencies to prevent future hassles. Also, talk to neighbors about what designs and materials work or do not work for your area. Their experience can help eliminate unforeseen problems.
Shorelines are vulnerable to erosion caused by waves and ice. Waves, caused naturally or by boats, beat against the shore and eat away at the shoreline. Waves, wind, and expansion pressure grind ice along the shore. The size of the waves and the stability of the shore are the largest factors influencing the amount of erosion. The average size of the waves varies around the lake. Protected shores experience small waves while those shores exposed to prevailing westerly winds tend to be subject to the largest waves. The stability of the shore is determined by the type and size of material making up the shore and the slope of the land. Soft or fractured stones such as the shale found around Keuka Lake are easily eroded by wave action, especially on steeper slopes. With low angle slope, the energy of the wave is quietly dissipated as it washes over the shore. Much more of the wave's energy impacts a steeper slope when a wave crashes against it.
A shoreline can be protected by increasing resistance to wave action, reducing wave impact, or a combination of the two. Protection can be achieved through structural and nonstructural modifications to the existing shoreline.
Beach sloping - The area near the lake shore can be made less susceptible to erosion by flattening the slope of the shore. A flatter slope allows waves to dissipate their erosive energy without damaging the shoreline. The ideal slope ratio is approximately 10:1. Essentially, the shore area from the mean high water level (715.30 ft) inland the distance that waves wash up would become a gravel beach without much vegetation. The gravel serves as additional protection.
Landscaping - Using plants to stabilize a shoreline is a simple way of reducing erosion. Plant roots help to hold soil in place and the plants themselves act as buffers, absorbing wave energy during storm events and flooding. This method works best in conjunction with other methods such as a low-angled slope. In sheltered areas, vegetation can be grown right to the water's edge. In exposed areas, plants and trees are not able to withstand the constant battering by waves and should be planted out of reach from continuous wave action.
Trees are one of the most effective plants at reducing erosion. The roots are strong and far reaching, solidifying large areas. At times it is necessary to remove a dying or problematic tree. Leaving the stump will help hold the soil until other vegetation can grow or the tree replaced.
Structure controls, otherwise known as re vetments, protect shoreline by covering the area susceptible to erosion. The rocks, logs, metal and concrete that these structures are made of are able to withstand the force of waves that the endangered shore could not.
In determining what type of structural control to use, a few criteria must be taken into consideration. The main concern is the average wave height at the mean high water level. In lakes, the height of waves, measured from the trough to the crest, is determined by wind speed and the distance the wind travels across the lake. Structures are usually designed to be higher than the expected height a wave will climb up the shore or structure, otherwise known as runup.
Other factors that need to be taken into consideration before construction is the mean high water level (MHWL), the stability of the shoreline, and steepness of slope. If the shoreline contains fairly loose soil, compaction of the soil is necessary before construction. Many revetments perform better and last longer if placed on lower angled slopes. Do not forget to check with the local code enforcement officer (CEO) and the NYS DEC about ordinances and permits needed.
When designing a revetment, there are several critical areas of the structure. These include:
- Protect the toe (or base) from scouring due to waves. An undercut structure will eventually fail and need replacement.
- Protect the revetment from overtopping under normal lake conditions by making sure it is tall enough. Water splashing on unprotected ground can cause erosion behind the protection, creating the potential for failure.
- Protect the flanks from erosion to prevent failure.
- Allow for seepage from behind the structure by using filter cloth or a sand filter behind the revetment. Most shoreline protection structures are not built to withstand major storms and water will get behind the structure. When that does happen, there needs to be a mechanism for the water to leave without undermining the revetment.
Riprap and rootrap - Riprap is constructed with large stone or gravel that is placed on the natural or artificially graded shoreline slope. Often, the larger stones are "chinked" with smaller stones to fill crevices and enhance coverage and stability. Rootrap is constructed just like riprap, but topsoil is placed over the rocks, and vegetation is planted. The roots from the plants hold the soil in place and stabilize the movement of the riprap. Specific criteria for the design of riprap structures include:
- Extend riprap up the shore at least 0.5 feet above the height the average wave travels up the shore at MHWL.
- Place riprap at least the same distance below the MHWL.
- The median size of the riprap stone is determined according to the wave heights and the slope of the shoreline. Consult the Natural Resource Conservation Service (formerly the Soil Conservation Service) or your local Soil and Water Conservation District for technical assistance.
- A minimum thickness of 2.5 times the median rock size.
- Bedding material, such as gravel, should be at least 6 inches thick, or use filter fabric.
- Anchor the riprap if the shore has slopes of 6:1 or steeper.
Gabions - Gabions are rectangular or square wire baskets that are filled with stones 4 to 8 inches in diameter. Once the shoreline is prepared, the baskets are put in place and filled with stones. A typical basket is three feet wide and are available in lengths of six, nine, or twelve feet. The height or thickness ranges from nine inches to three feet.
Individual baskets are wired together, filled with stone and wired shut. Gabions are ideal in areas where they won't be used as a foot path. The baskets might require some occasional maintenance. It is vital that the stones are packed inside the baskets in order to make the structure rigid.
Interlocking blocks - Interlocking blocks are simply pre-made concrete blocks that lock together. There are several styles available that local contractors or landscaping supply companies can provide more information about. In building an interlocking block structure, usually one layer of blocks is sufficient. The interlocking mechanism gives the structure stability but allows the structure to move and settle without breaking. Depending on the conditions of the site, the blocks weigh anywhere from 30 to over 100 pounds. In many cases, the blocks can be put into place by hand.
Retaining walls - Retaining walls, also known as sea walls, bulkheads, or breakwalls are rigid structures that are placed vertically or at a slight angle inland to form a barrier between the shore and water. Retaining walls are either cantilevered or anchored. A cantilevered retaining wall is a sheet pile supported entirely by the ground. Sheet piles are typically sheets of steel bent like a stretched out "Z" and are driven into the ground. They also can be wooded planks set on end. An anchored wall is similar to the cantilevered wall, but there are anchors holding the upper portions of the wall.
The following list gives some of the design criteria for retaining walls that the Natural Resource Conservation Service recommends:
- Steel sheet piles can be driven into hard soil and soft rock. Aluminum and timber sheet piles can be driven into softer soil.
- For cantilevered retaining walls, the sheet piling should be driven deep enough to resist overturning, which usually requires a depth of two to three times the free standing height, depending on the foundation characteristics at the site.
- For an anchored retaining wall, sheet piling should be embedded to a depth one and a half to two times the freestanding height. Again, the foundation characteristics may indicate shallower or deeper penetration.
- The top of the retaining wall should be at least one foot above the height a wave reaches when it breaks against such a structure.
- Wing walls should be used to prevent flanking (erosion at the end of the wall). If the ends are not protected, erosion could produce a retreating shoreline at each end of the wall.
- The suggested minimum thickness for metal sheets is 0.109 inches; for wood planks, 2 inches; for wood poles, 4 inches.
Many of the shoreline properties around Keuka Lake also have streams that run through or enter the lake on the property. Stream erosion control structures are subject to different standard than lake structures. Running water can be much more destructive than wave action and the measures used to prevent erosion need to reflect this reality. Contact the local Soil and Water Conservation District Office for more information.
Lake Levels and Flooding
The water level in Keuka Lake during the year depends upon the amount of water entering and leaving the lake. The Keuka Lake water shed is approximately 175 square miles and feeds a lake of only 17.5 square miles. The watershed to lake area ratio is about 10:1. Under saturated conditions in the watershed, this ratio means that one inch of rain falling on the entire watershed would result in a 10 inch rise in lake level. Water exits the lake through the Keuka Outlet where it tumbles 270 ft over 8 miles to Seneca Lake. From there, the water travels to the Seneca River, Oswego River and ultimately into Lake Ontario.
The gates regulating the water level of Keuka Lake are operated by the Penn Yan Municipal Utilities Board. In 1994 three additional gates were added to the three that existed in the dam in Penn Yan. The combination of six gates and the steep drop down to Seneca Lake enable the Utilities Board the greatest control over the lake level of all the Finger Lakes. The catch is, because of the size of the Seneca Lake, its watershed, and the inability to move large amounts of water through its outlet quickly, it is necessary to control how much water is released from Keuka Lake to help minimize downstream flooding.
The Utilities Board strives to raise or lower the lake level to match the level recommended by a guide curve formulated to optimize lake water levels throughout the year. The curve ranges from a desired water level of 712.00 ft above mean sea level (ft amsl) in the winter to 714.5 ft amsl in the summer. The high water levels in the summer allow use of docks while minimizing flooding in low lying properties and supplying enough water for fish and wildlife. The lower water level in the winter serves as a buffer against spring snowmelt and runoff.
For large storm events such as 1972's Hurricane Agnes, the largest storm of this century, the outlet cannot remove the water fast enough to prevent the lake level from rising. The amount of flooding from these storms depends on the lake level before the event, what conditions exist in Seneca Lake, how much prior notice the Municipal Utilities Board has, the amount of rain and/or snow melt, and the condition of the ground in the watershed. Frozen or saturated soil allows most of the water to run off into the streams and the lake. The largest increase of lake level each year normally occurs during spring runoff when many of these conditions exist. In January 1996, a combination of warm temperatures causing snow melt and rain caused the lake level to rise precipitously. Even with the new gates wide open, the lake level rose three feet in a matter of hours.
For the low lying land around the lake, flooding of property begins at about 716.5 ft amsl. To help prevent flood damage, it is recommended that all buildings be built above the 10 year flood level, 717.9 ft amsl. This is also the elevation necessary to be eligible for federal flood insurance.