▁are ▁relatively ▁un imp act ed . ▁The ▁stream ▁has ▁relatively ▁high ▁water ▁quality ▁even ▁where ▁it ▁flows ▁through ▁a ▁concrete ▁channel . ▁In ▁a ▁study ▁by ▁the ▁Sus que h anna ▁River ▁Bas in ▁Commission , ▁it ▁was ▁found ▁not ▁to ▁fail ▁any ▁water ▁quality ▁standards ▁either ▁during ▁base ▁flow ▁or ▁storm ▁flow ▁conditions . ▁However , ▁a ▁study ▁from ▁the ▁previous ▁year ▁found ▁concentr ations ▁of ▁sod ium ▁and ▁al kal inity ▁exceed ing ▁the ▁threshold ▁for ▁concern . ▁In ▁the ▁early ▁ 1 9 0 0 s , ▁Spring ▁Brook ▁was ▁a ▁clear ▁stream ▁in ▁its ▁upper ▁reaches . ▁However , ▁by ▁the ▁time ▁it ▁reached ▁the ▁property ▁of ▁the ▁Du ▁Pont ▁Pow der ▁Company , ▁it ▁was ▁affected ▁by ▁sl ush ▁p ump ed ▁into ▁it ▁by ▁the ▁Pennsylvania ▁Co al ▁Company . ▁ ▁Between ▁ 1 9 7 1 ▁and ▁ 1 9 9 0 , ▁the ▁stream flow ▁of ▁Spring ▁Brook ▁r anged ▁from ▁ 0 . 9 0 0 ▁to ▁ 2 7 . 0 ▁cub ic ▁feet ▁per ▁second . ▁The ▁dis charge ▁r anged ▁from ▁ 0 . 0 6 ▁to ▁ 2 2 ▁cub ic ▁feet ▁per ▁second ▁in ▁the ▁ 1 9 7 0 s . ▁The ▁g age ▁height ▁of ▁the ▁stream ▁in ▁the ▁ 1 9 7 0 s ▁r anged ▁from ▁. ▁The ▁peak ▁annual ▁dis charge ▁of ▁the ▁stream ▁at ▁its ▁mouth ▁has ▁a ▁ 1 0 ▁percent ▁chance ▁of ▁reaching ▁ 5 0 5 0 ▁cub ic