Arcadia Lake is located in Oklahoma County, approximately 1.5 miles southwest of the town of Arcadia, in the metropolitan areas of Oklahoma City and Edmond. Arcadia Lake lies in the Central Great Plains ecoregion, and is characterized by slightly irregular plains with shallow relief originally vegetated with bluestem/grama prairie, bluestem prairie, or buffalo grass. The lake was formed in 1986 by impounding the Deep Fork arm of the Canadian River below its convergence with Spring Creek. At conservation pool elevation of 1006 NGVD, Lake Arcadia is a 1,725 acre reservoir with a volume of 29,705 acre-feet, mean depth of 17 feet and maximum depth of 49 feet. Arcadia Lake has approximately 26 miles of shoreline and a watershed area of 105 square miles. Water released from Arcadia Lake flows east into the Deep Fork of the Canadian River until it reaches Lake Eufaula.
Arcadia Lake is a source of recreation for the Oklahoma City metropolitan area. Popular recreational activities include boating, sightseeing, camping, picnicking, fishing, swimming, skiing, sailing, group meetings and hunting. Arcadia Lake is unique because it is the only municipal water supply reservoir in Oklahoma County that allows swimming. Although a recreational destination for many, Arcadia Lake is classified as eutrophic with water quality problems. Historical problems in Arcadia Lake include excess nutrients, sediment, pesticides, metals, fecal bacteria, and trash. These concerns helped initiate a Clean Lakes Diagnostic/Feasibility Study of Lake Arcadia. Objectives of the study were to diagnose the source of eutrophication, assess the potential impact of lake sediment on fish and wildlife propagation and suggest alternatives to mitigate diagnosed lake problems.
Water quality sampling occurred at regular intervals from February, 1996 through September, 1997. Stormwater data were collected 18 times during the period between February 18, 1997 and September 23, 1997. Collections were taken 14 times during high flow events and 4 times during low flow. Lake sediment was sampled in March of 1997 in cooperation with Region VI EPA to screen littoral sediment for toxicity.
Arcadia Lake has a relatively short residence time with a moderate sedimentation rate. Gross sedimentation for Arcadia Lake since impoundment was estimated at 105 acre-feet per year from 1986 to 1997. Mean lake depth has reduced 0.2 feet, with a loss of approximately 1162 acre-feet of volume. 1997 reservoir volume was estimated at approximately 29,705 acre-feet at conservation pool. At the current rate of sedimentation, the portion of the conservation pool allocated for sediment should be filled in 2036. Shoreline erosion was also identified as a contributor to the turbid lake water. Shoreline erosion contributes to decreased water clarity, increases evaporative water loss, loss of property and presents increased risk to recreationalists.
Arcadia Lake was classified as a eutrophic reservoir. Available historical algae data supports ongoing eutrophication. Application of trophic state indices and TN:TP ratios indicate that nitrogen rather than phosphorus is the limiting chemical nutrient. Application of Carlson's Trophic State indices indicate that light availability limits algae growth at times when nitrogen is not limiting. A detailed analysis of the algae and zooplankton communities suggest that an over- abundance of zooplankton feeding fish may be a contributor to excessive algae growth in the summer.
No toxicity was expressed in any sediment tests. Chemical analysis did indicate significant, but relatively low level, sediment contamination. While additional toxicity tests would aid in determining sediment quality, the existing data indicate that pollutants, in combination, are not present at toxic levels. The data indicate that nonpoint source controls to reduce pollutant loads (metals, PAHs) would benefit sediment quality and reduce risks to benthic organisms.
Non-point sources were identified as the contributors to Arcadia Lake eutrophication and low level toxic contamination. The feasibility portion of the study was designed to identify viable management options to eliminate or reduce diagnosed problems. Feasibility options have been broken into two sections: in-lake and watershed. In-lake options outline management techniques that can be applied within the confines of the lake, an area of approximately 1,800 acres managed in concert by the City of Edmond and Tulsa District Corps of Engineers. Watershed options outline techniques to be applied in the lake's drainage basin, approximately 67,000 acres in size and managed by a conglomerate of Oklahoma City, City of Edmond, the State of Oklahoma, individual landowners and businesses.
Arcadia Lake would benefit immediately from a comprehensive program to control shoreline erosion. Shorelines receiving high recreational use or large waves will require hard treatments such as rip-rap, rock gabions or bulkheads. Soft treatment using dead and living vegetation would provide control in the lower impact areas for approximately one-quarter the cost of hard treatments. Aside from reduced cost of implementation, soft treatments have secondary benefits for fish, wildlife and aesthetics. Stocking of top predator fishes such as the sauger-walleye or striped bass-white bass hybrid shows promise to help reduce summer algae growth through food web manipulation. Techniques such as aeration or reservoir partitioning should be evaluated based on whether watershed improvements are made.Watershed Measures:
Approximately 60% of the Arcadia Lake watershed is designated as some type of urban land use. Runoff from rainfall events accounts for 90% of the lake water recharge. This runoff is heavily laden with solids and nutrients from the watershed. Although most of the material washed into the lake settles out in the upper end, the soluble nutrient portion stimulates algae growth. The myriad of activities associated with urban land use (ranging from vehicular traffic to groundbreaking construction to aging sewerage systems or homeowner lawn fertilization) can account for the lion's share of non-point source pollutant loadings to Arcadia Lake.
Soil stabilization and flood storage are general measures that will show the greatest improvement to inflowing water quality. The Urban Water Resources Research Council of the American Society of Civil Engineers (ASCE) entered into a cooperative agreement with the U.S. Environmental Protection Agency (EPA) to develop a scientifically-based approach to evaluate the effectiveness of urban stormwater runoff BMPs nationwide. When completed, an extensive screening of over 800 existing BMP's with performance measures will be available for use on personal computers. For updates on this project please visit the following website: http://www.asce.org/peta/tech/nsbd01.html
Specific BMPs to employ in the watershed should be determined in consultation with the Oklahoma Conservation Commission and other concerned state and federal officials, such as the United States Department of Agriculture, the National Resources Conservation Service, the Agricultural Stabilization and Conservation Service, City of Oklahoma City, City of Edmond and individual landowners.