ANALYSIS OF WATER-LEVEL--LAKE JACKSON


 PERCENT OF TIME LAKE-LEVEL RISE EQUALLED
 OR EXCEEDED THAT INDICATED
Figure 16.-Cumulative frequency curve for net yearly lake-level change of
 Lake Jackson.

not been affected by urbanization within its tributary area, con-
tinued urbanization may increase the total inflow to the lake.
The threat of increased damage by future floodings leads to the
consideration of methods of maintaining the lake below a given
maximum level. However, the diversion of water from the lake
to control high levels during wet periods will tend to decrease the
utility of the lake during dry periods. Thus, methods of maintain-
ing the lake level above a given minimum level during dry periods
also may be considered.


 RISING LAKE LEVEL

 The design of an outflow system to maintain the lake level
 below a given maximum level should be based on data representa-
 tive of the maximum rise that probably will occur. The outstanding
 rise of Lake Jackson, within the period of record, occurred from
 December 1, 1964 to April 30, 1965, when the net rise was 1.6 feet
 for the month of December alone and 5.2 feet for the 5-month
 period. Preventing any appreciable cumulative rise of the lake
 level during this prolonged and unusually wet period would have
 required the removal of a volume of water each month equivalent