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Crystal/Keller Lake ater uality Problems <br />and Causes <br />The water quality assessment portion of the UAA determined that Crystal <br />and Keller Lakes suffer from two primary water quality problems: summer <br />algal blooms and excess lake weeds. The algal blooms are caused by high <br />phosphorus Ievels, due to poor quality urban stormwater runoffentering the <br />lake. The problematic lake weeds are an exotic lake weed species called <br />curlyleafpondweed, which dies back inmid-summer each year, fiurther <br />increasing the lakes' phosphorus concentration and algal abundance. <br />Nutrient-rich lake sediments also recycle phosphorus back into the lake <br />water during summer months. The following page explains the recommended <br />water management strategy for handling these problems. <br />Crystal Lake Annual Phosphorus Budget (9082 Ibs) <br />oriel Calibration Year (2002) Using Existing Land Use <br />airoaworA+sr,.e A.n~ <br />~ s~ <br />Gun~mutanv~ <br />~vron~a <br />Land = 36° <br />ciao <br />9SX <br />aa~ <br />1~ <br />Asae <br />8°d. <br />Haas <br />oX <br />A72® <br />QX <br />CuxlYim~r Wo.6ask <br />~s~: <br />~~i r. <br />SAX <br />snoslo ~dn1 <br />P <br />t9X <br />__ _ C I Lake W teed -_..~ ~ .~. _.~ <br />-,. , ~ - <br />~ ` ~ ;~ ~ Existing apd FuU t3evei rn land U~ ' ,> ~ $~~w °~ * ;~ <br />.~ 3 V ~ ~7JF , <br />k ~ ~ ~ <br />~ ~~ , ~ ~- ~- ~ r° <br />~ ~ c ~ ~ a~~~ ~" ~ ~s ~ ~~N <br />,~ r ~ T 3~ 1 W <br />~- .~..~.,, C - <br />_ ~ JQ'~,,,'' ~_ G•~cvn <br />~ ~ 3 a , ~' tF 1~~ 44~`~[ ~~ ~~ ~=+~^ is.. a.,d.v.c°..,.re,,.: <br />` 114 .: ,-.. :~~'' r ~~ .~.,..e..~,..,..-~- ~_- q4 ..u <br />__ .ter _ •3.~ ,x ~. ~ ._...., ~ [_ 7 ~wv.u,w. ~ «w- <br />~` <br />,;, <br />,.~ <br />Curlyleaf pondweed is a major problem <br />that affects recreational use of both <br />Crystal acrd Keller Lakes. <br />The UAA includes data such as this pie <br />chart; which shox~s the breakdown of <br />sources of the annual phosphorus load to <br />Crystal Lake. See the map on page 9 to <br />cross-reference the source/location codes. <br />A similar pie chart for Keller Lake is <br />included in the UAA. <br />Investigative Techniques <br />Used in U,4A Process <br />The UAA process included an intensive <br />lakewater quality study, P8 computer <br />simulation modeling ofrunoffwater <br />quality, lake hydrologic and phosphorus <br />budget analyses, and an analysis of the <br />likely water quality improvement benefits <br />of several lake water management <br />strategies. Secchi disc readings were <br />conducted biweekly throughout the open <br />water season as a general indicator of <br />water qualify. <br />T{re UAA found that watershed land use directly <br />it~uences fhe lakes' annual water and <br />phosphorus inputs. <br />ll <br />CL•ai <br />au K.'r~, ww twt~+ <br />cw~.s <br />oX <br />