Dorchester Star - - Re­gional -

EAS­TON — The Ch­e­sa­peake Bay’s wa­ters re­ceived one of the best scores of the last few decades, ac­cord­ing to a re­port card re­leased Tues­day, May 17, by the Univer­sity of Mary­land Cen­ter for En­vi­ron­men­tal Sci­ence.

Over­all health of the Bay im­proved in 2015, scor­ing a C, or 53 per­cent, ac­cord­ing to the re­port.

Sci­en­tists are cred­it­ing a num­ber of fac­tors to the im­proved score, in­clud­ing mod­er­ate weather, sewage treat­ment up­grades, use of win­ter cover crops by farm­ers and re­duc­tions in at­mo­spheric ni­tro­gen de­po­si­tion.

No over­all scores for re­gions of the Bay were lower than last year, ac­cord­ing to the re­port.

But, out of all the re­gions, the Chop­tank River’s health im­proved the most, due to in­creases in un­der­wa­ter grasses and an im­proved ben­thic com­mu­nity — clams, oys­ters, mus­sels and worms.

The mid-stem of the Bay had the high­est wa­ter clar­ity of all the re­gions, but also had the worst score for dis­solved oxy­gen — mostly in its deep seg­ments — which the Bay’s or­gan­isms need to sur­vive.

In­creased wa­ter clar­ity can lead to resur­gences of aquatic grasses, which sig­nif­i­cantly im­proved in 2010 and are one of the most im­por­tant habi­tats in the Bay re­gion, pro­vid­ing a home for species like blue crabs and striped bass.

Bay­wide, though, wa­ter clar­ity was con­sid­ered poor, but still an im­prove­ment from last year.

“Al­most all Ch­e­sa­peake Bay trib­u­taries ex­hib­ited a gra­di­ent in wa­ter clar­ity, with murkier wa­ter in the mid to up­per reaches and clearer wa­ters in the lower reaches,” the re­port reads. “The Bay’s main­stem ex­hib­ited a sim­i­lar pat­tern, with murkier wa­ter in the Up­per Bay and clearer wa­ter in the Mid and

Lower Bay re­gions.”

Bill Den­ni­son, vice pres­i­dent for sci­ence ap­pli­ca­tions at the Univer­sity of Mary­land Cen­ter for En­vi­ron­men­tal Sci­ence, said im­prove­ments are ex­pected af­ter a drought year, be­cause nu­tri­ents aren’t be­ing washed into the Bay as much.

“How­ever, in 2015 stream flow was be­low nor­mal, but nowhere near the drought con­di­tions in 1992 and 2002,” Den­ni­son said. “Thus, the high score for 2015 in­di­cates that we’re mak­ing progress re­duc­ing what’s com­ing off the land.”

Ex­cess nu­tri­ents, like ni­tro­gen and phos­pho­rus, can runoff into the Bay’s water­ways and fuel al­gae growth blooms, re­sult­ing in poor wa­ter qual­ity and and can lead to re­duced dis­solved oxy­gen lev­els. Al­gae blooms can also block sun­light from get­ting to the Bay’s un­der­wa­ter grasses.

While ni­tro­gen lev­els im­proved Bay-wide, the Chop­tank and Up­per East­ern Shore rivers scored among the worst for to­tal ni­tro­gen. Trib­u­taries across the Bay had higher con­cen­tra­tions of ni­tro­gen in their up­per reaches and lower con­cen­tra­tions in the lower re­gions, and the main­stem of the Bay ex­hib­ited a sim­i­lar pat­tern.

“Higher con­cen­tra­tions of ni­tro­gen in the mid to up­per reaches of the trib­u­taries can, in part, be at­trib­uted to runoff of ex­cess ni­tro­gen from fer­til­iz­ers, power plants, and fac­to­ries get­ting into creeks, streams, rivers, and ground­wa­ter that then feed into the Bay,” the re­port reads.

One score Bay-wide de­clined — to­tal phos­pho­rus. The mid-Bay and Chop­tank River scored the sec­ond and third high­est re­spec­tively for phos­pho­rus, though. Phos­pho­rus con­cen­tra­tion trends in the wa­ter were sim­i­lar to ni­tro­gen, ac­cord­ing to the re­port.

Of­fi­cials on Tues­day were pleased with the re­sults, which have been trend­ing up the past few years, and credit the im­prove­ments to the Bay re­gion’s ef­forts to re­duce pol­lu­tion are work­ing.

“We should take the op­por­tu­nity to cel­e­brate th­ese re­sults,” said Nick DiPasquale, di­rec­tor of the fed­eral Ch­e­sa­peake Bay Pro­gram.

“But we should also rec­og­nize that the long term suc­cess of our work to re­store wa­ter qual­ity and the health of this vi­tally im­por­tant ecosys­tem will de­pend on step­ping up and sus­tain­ing our ef­forts over the long-term to re­duce nu­tri­ent and sed­i­ment pol­lu­tion dis­charges to streams and rivers through­out the water­shed,” he said.

Peo­ple can see the re­port card at chesa­peake­bayre­port­

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