the 1980 appointment of a park coordinator who would start devising details of a "master plan" for the park. In 1985, a study recommended ecological restoration of the lake and forest, which had been overtaken by invasive species introduced during highway construction. Since then, there have been seven plans for restoring natural elements of the park, as well as three plans for park restoration. Gradual improvements began taking place in the late 1980s, including the addition of new pathways, signage, and security, as well as the restoration of playgrounds and other recreational facilities. In January 1988, NYC Parks conducted a study to determine the specific elements of the park that needed restoration. Highway structures were also reconfigured to clean runoff from these structures. An excavation in the 1990s yielded over 2,500 artifacts. The city built the Croton Water Filtration Plant, a drinking water treatment facility, under the park's Mosholu Golf Course. Plant operations began in 2015. The plant was needed in order to filter contaminants from urban runoff pollution in the Croton River watershed and protect the public from Giardia and Cryptosporidium, microorganisms which can cause serious health problems. The Croton plant was built after a lawsuit was filed in 1997 against the city by the U.S. Environmental Protection Agency (EPA), the U.S. Department of Justice and the State of New York. The city settled the suit and a consent decree was issued with the condition that the city would build the plant by 2006. The project experienced delays and ballooning costs due to objections from the local community, which required the city to propose alternate sites for the plant. The plant was built 160 feet (49 m) below the Mosholu Golf Course, at a cost of $3.2 billion. To lessen the disruption caused by the plant's construction, in 2010 the city used mitigation funds from the construction budget to restore the Van Cortlandt Park Parade Ground. The Sachkerah Woods Playground, located at the park's southeast corner near the Mosholu Golf Course, was also built using Croton mitigation funds. As part of the "Van Cortlandt Park Master Plan 2034", critical ecological elements of the park, such as the forest, the rural landscape, and Tibbetts Brook, would be restored, and the brook would be diverted. when the report was written, the lack of natural drainage points within Van Cortlandt Park led to the flooding of recreational areas within the park during