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of pollutants to the lakes. Suspended solid loading and E. coli loading were greatest from Crooked Creek, while ortho-phosphorus loading was most pronounced from Lozier's Creek. Crooked Creek delivered the most sediment, total phosphorus, and bacteria per acre of watershed. At base flow conditions, the Highlands Park inlet also contributed substantial amounts of the pollutants despite having a relatively small watershed. (Click Here for summary of lake improvement projects.)
Big Chapman Lake is best classified as a mesotrophic lake in that it supports only moderate rooted plant growth with moderately clear water. Bluegill and bass dominate the lake's fish community, while a diverse mix of native pondweeds, eel grass, and emergent vegetation grows in patches throughout the lake. Big Chapman Lake generally has better water quality than most other Indiana lakes. Phosphorus concentrations, however, appear to be increasing since the mid-1990's, while the percentage of the water column containing oxygen appears to have been decreasing recently. Secchi disk transparency of Big Chapman Lake is holding steady or slightly decreasing. In general, trophic state indices and water quality parameters indicate that although water quality in Big Chapman Lake is good, concern for worsening conditions is warranted. Phosphorus modeling of Big Chapman Lake and its watershed suggests that 22% of the phosphorus in the lake originates from internal sources.
Little Chapman Lake is a eutrophic lake with some rooted macrophyte problem areas and relatively poor transparency. As is characteristic in many eutrophic systems, bluegill and gizzard shad have historically composed most of the fish biomass. Little Chapman Lake also tends to have worse water quality than most other Indiana lakes and more problems with the invasive Eurasian water milfoil. While mean historic total phosphorus concentrations in the lakes have shown a slight decreasing trend in the past decade, Secchi disk transparencies have been decreasing. The same phosphorus modeling procedure for Little Chapman Lake indicates that 37% of total phosphorus loading originates from internal sources.
The two Chapman Lakes are different with respect to physical characteristics as well. For example, Little Chapman flushes or replaces its water about three times per year and is affected by a larger watershed than Big Chapman. Although Big Chapman currently has better water quality than Little Chapman, it takes two years to flush its water. Due to the shorter flushing rate of Little Chapman, it can respond more quickly to improvements within its watershed. By the same token, because Big Chapman takes longer to flush, more serious, long-lasting problems may result if watershed and recreational use issues are not quickly addressed.
Although water quality in Big Chapman is relatively good, it is a valuable resource meriting conservation. Additionally, management efforts applied to Big Chapman will also improve Little Chapman since its water discharges to Little Chapman. Improvements can be achieved by implementing a variety of management strategies with first priority given to the Crooked Creek subwatershed. These include implementing bank and channel erosion control techniques, installing Best Management Practices (BMPs) and restoring wetlands within the watershed, and employing stormwater treatment and conservation design in new development areas. Lozier's Creek subwatershed and Arrowhead Park subwatersheds of Little Chapman are also priority targets for implementation of various management recommendations.
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