Final Report: A Sustainable Approach to Preserve the Choctawhatchee Coastal Dune Lakes of FloridaEPA Grant Number: SU833550
Title: A Sustainable Approach to Preserve the Choctawhatchee Coastal Dune Lakes of Florida
Investigators: Jawitz, James W. , Bhadha, Jehangir H. , Brenner, Mark , Brown, Gordon , Bunch, Aaron , Kaplan, David
Institution: University of Florida
EPA Project Officer: Nolt-Helms, Cynthia
Project Period: September 30, 2007 through March 31, 2008
Project Amount: $9,941
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet (2007) RFA Text | Recipients Lists
Research Category: Nanotechnology , Pollution Prevention/Sustainable Development , P3 Challenge Area - Water , P3 Awards , Sustainability
Coastal dune lakes are fresh water basins that are delicately perched above the coastal salt water fringe, making them unique ecosystems. Over the past decade, a string of 18 such lakes in the Choctawhatchee basin of Florida’s panhandle has attracted vast urban development. With changing land-use practices, and close proximity to the Gulf of Mexico, these lakes are under a constant threat of deteriorating water quality, and salt-water mixing. Concerns about the future “health” of these unique eco-systems have prompted Walton County to foster a long-term collaborative commitment from stakeholders, citizens, and research teams alike in sustaining the future of the lakes.
The objectives of the project were to: (i) Investigate the current condition of the lakes; including water quality, and land-use practices surrounding them. (ii) Based on our investigation, identify pertinent issues concerning the lakes, and provide recommendations that will help decision makers develop a sound lake management plan in the future.
Scattered along a 30 mile coastline just east of Destin, Florida, lies a series of 18 named coastal dune lakes distributed between Walton and Bay County. The lakes are irregularly shaped, typically shallow (2-6 m deep), located within a mile inland from the coast. The water is composed of a mix of fresh and salt water, accumulated from runoff, groundwater seepage, direct precipitation, and storm surges. The lake water is generally colored (tea or black colored) due to watershed contributions of dissolved organic matter. While these lakes are typically exposed to sub-tropical weather conditions they are also impacted by hurricane activity.
The lakes are unique in their intermittent connection (outfalls) to the Gulf. This periodic connection serves as control for flood-level waters when the dunes are breached, and lake water flows via a conduit to the Gulf. Depending on tides and weather conditions, salt water and biota from the Gulf fills the void left behind by the lowered water level of the lake until equilibrium is reached. This exchange forms a brackish water-body, creating a temporary estuarine ecosystem. Each of the coastal dune lakes is individually characteristic, with outfall openings varying in length, frequency and duration. As a result, some of the lakes can be completely freshwater (salinity < 0.2 ppt), some brackish and/or salty, with varying degrees between stages (0.5-12.1 ppt). This changing condition of water makes these lakes biologically diverse systems with a dynamic nature. The nutrient concentration (primarily TP and TN) fluctuates seasonally and spatially from one lake to another, possibly related to the density of urban development surrounding the lakes, and the runoff associated with it.
With the ever rising demand in lake front properties, Walton and Bay counties has seen an increase in population growth over the last decade. Using GIS applications we were able to gauge this increase in urban development surrounding the lakes. If this trend continues, concerns over issues such as, water quality, outfall management, land-use practices, and greater public awareness, need to be addressed.
Based on our findings from Phase I we are able to summarize the following conclusions:
Lake salinity and outfall management:
The salinity of these lakes is directly related to the mixing with salt water from the Gulf. This salt water mixing occurs through two possible ways, (a) ground water seepage with daily tidal fluctuations, and (b) surface mixing at times of “blowouts”. While tidal fluctuations can control lake salinity only slightly, the high salinity observed in some of the lakes was directly related to the outfall being open to the Gulf. The lakes which showed the highest salinity all had their outfalls open to the Gulf at the time of sampling. While the ones whose outfalls were not breached showed a significantly lower salinity. Trying to physically manage the outfalls has been proposed recommended, however no such decision can be taken without scientific evidence that shows that outfall management will in fact improve lake water quality, prior to dealing with the legalities related to the issue.
Over the last four decades land use practices surrounding these lakes have seen a considerable change, the most dominant being within the last decade. These changes primarily involve the transformation of historic flatwoods landscape into sprawling urban development projects. A good portion of the land has also been converted for recreational use (e.g. golf courses), while the rest remain as transitional (zoned, and sold to private land owners). Campbell Lake’s watershed is completely undeveloped “pristine” because it located within the Top Sail Hill Preserve State Park. Hence, there is particular interest in protecting the lake, as it can provide a baseline to measure impact compared to other lakes. Of all the lakes, Oyster Lake has the highest development within its watershed. Draper Lake’s watershed has the largest potential for development. A large portion of Western Lake’s watershed remains undeveloped; its future will depend on individual landowners. Camp Creek Lake is the most recent to be developed, over 50 % of the watershed will likely remain undeveloped protected by State Parks. While each lake has varying degrees of protected land within its watershed, Walton and Bay County land use decisions will influence development, and hence the future of the lakes.
Fluctuating trends in nutrient concentrations:
Lake water quality has been periodically monitored since 1990’s by Florida Lakewatch and Choctawhatchee basin volunteers. Oyster Lake seems to show the highest rise in nutrient concentrations between 2001 and 2005, rising from 50 to 200 μg/L; and 100 to 1200 μg/L for TP (total phosphorus) and TN (total nitrogen) respectively. Surprisingly, even Campbell Lake which is located in the State Park relatively protected from development has shown increase in nutrient levels over the past decade. This may have implications for non-development related nutrient sources such as ground water seepage from neighboring watersheds. However, water quality of Camp Creek Lake seems to be rather robust, because its extensive sampling history shows no significant increase in nutrients levels. Seasonal variations in nutrient concentrations are prominent in all the lakes with higher concentrations seen in the summer months than in the winter.
A need to promote an integrated education campaign:
As a result of our numerous interactions with local residents, visitors, and members of CBA, who deal with the dune lakes on a daily basis, we feel that there is a vast difference in public perception of the dune lakes. This may well be because of the lack of rudimentary information readily accessible for the local residents and tourists alike, educating them of the uniqueness of these lakes, and issues that may threaten its fragile ecosystem. Except for the one information kiosk located within the Topsail National Park, and maintained by the park rangers, there are no other signs or information boards located along this 30 mile stretch of “Dune Lake Country”. The USEPA has outlined two out of six guidelines in the National Pollutant Discharge Elimination System Program that deals with public education/outreach, and public participation/involvement. We believe that an Integrated Education Campaign (IEC) is needed to provide a strong foundation that will help protect and preserve the lakes.
Proposed Phase II Objectives and Strategies:
Our goal for Phase II will be to implement a stringent Integrated Education Campaign that will promote local and global awareness of the lakes’ uniqueness; and help generate a unified perception of the relevant issues pertinent to these lakes. The campaign will be tri-faceted, involving specific objectives that will target education, research, and outreach.
- Education: Impart awareness by building outdoor information/education kiosks, and signage boards at individual lakes that will provide information regarding the lakes current condition.
- Research: Teach classes at centers like the University of Florida and Okaloosa-Walton College, prompting research involving the dune lakes.
- Outreach: Conduct seminars and workshops on residential rain gardens; generate community involvement in the Florida yards and neighborhoods program.
It is obvious that the dune lakes are unique because of a variety of interesting points, and the spectacular views it provides. Our strategy will be to position the kiosks and signage boards in easily accessible places where tourists and residents can see them. We plan on having a grand opening of the kiosks and signs to promote our efforts in the community. The objective is to impart as much information about the lakes as possible, and provide contacts and web links for those who wish to explore further. We will include professors from various departments to conduct scientific research on related topics, and encourage them to use the lakes for field trips. Over time, people will be exposed to the dynamic behavior of coastal dune lakes, and public awareness would have increased.