Orig­i­nal­ly, the Oder was divid­ed into two main arms north of Oder­berg, of which the larg­er, known as the Oder, ran on the west­ern edge of the val­ley via Lunow, Stolpe and Criewen to Schwedt, while the sec­ond main arm, the Meglitze, on the east­ern edge of the heights via Hohen­wutzen, Zehden (Cedy­nia) , Bellinchen (Bielinek) and Peet­zig (Piasek) to Low­er Saat­en (Zatoñ Dol­ny). Below Schwedt and von Nieder­saat­en, the two main arms changed and branched out. To the north of Gartz and Greifen­hagen (Gryfi­no), two main arms could be seen again, from which the Oder on the west­ern edge led via Gartz and Stet­tin (Szczecin) into the Papen­wass­er, the Reglitz on the east­ern edge flowed into the Damm­schen lake. Both main arms were con­nect­ed to one anoth­er by numer­ous inter­me­di­ate arms.

Aim of the hydraulic engi­neer­ing mea­sures from 19th to the 20th cen­tu­ry was now the man­u­fac­ture and main­te­nance of a deep, high-per­for­mance pow­er hose up to the nat­ur­al receiv­ing basin, the Damm­schen lake. 19th to The 20th cen­tu­ry was now the man­u­fac­ture and main­te­nance of a deep, high-per­for­mance pow­er hose up to the nat­ur­al receiv­ing basin, the Damm­schen lake. The aim was to deep­en, short­en, straight­en the ship­ping route and make it nav­i­ga­ble at all times. In addi­tion, sand deposits were to be pre­vent­ed, the dis­charge of the flood was to be accel­er­at­ed and the receiv­ing water for the Oder­bruch improved. Last but not least, at the express request of the mead­ow own­ers, who did not want to do with­out the abun­dant fer­til­iza­tion with win­ter floods, the area should be able to be flood­ed with­out restric­tion by win­ter floods.

The Hohen­saat­en-Friedrich­sthaler water­way was cre­at­ed, which used the old Oder bed south of Schwedt, while north of Schwedt, was cre­at­ed for the real­iza­tion of the large ship­ping route Berlin — Stet­tin, i.e. for con­tin­u­ous use by ships with a load capac­i­ty of 600 t, and as a receiv­ing water of the Oder­bruch Canal punc­ture was required. The Ostoder, i.e. the for­mer Meglitze and today’s Stro­mod­er, was sup­posed to be the main riv­er to car­ry the amounts of water and sus­pend­ed mat­ter com­ing from the Oder course into the Damm­schen See by the fastest pos­si­ble route. The sum­mer dykes west of the Ostoder were to serve to hold the water from the upper reach­es togeth­er in a closed cross-sec­tion up to a water flow of 1,600 m³/sec. The pold­er area should only be flood­ed when the water lev­el is greater. As soon as the water lev­el on the Ostoder fell, the pold­er area should quick­ly dry out to the low­er Hohen­saat­en-Friedrich­sthaler water­way and to the West­oder. In order to ensure a year-round nav­i­ga­ble large ship­ping route and a secure flood­ing of the Oder­bruch, regard­less of the chang­ing water lev­el of the Oder, the Hohen­saat­en-Friedrich­sthal water­way was decou­pled from the Ostoder, which was expand­ed to the main stream, by a weir at Hohen­saat­en and a lock on the Schwedt cross­ing. It is only open to the north to the West­oder, but it was also sep­a­rat­ed from the riv­er Ostoder by the Marien­hofer weir near Fid­di­chow (Widu­chowa). How­ev­er, up to 650 m³/sec. can be dis­charged into the West­oder via this weir as soon as the Ostoder has reached a total dis­charge of 1,600 m³/sec. At the Hohen­saat­en weir, up to 20 m³/sec. can be dis­charged from the Stro­mod­er into the Hohen­saat­en-Friedrich­sthal water­way to reg­u­late the water level.

Between the Hohen­saat­en-Friedrich­sthaler Wasser­straße and the Stro­mod­er in the south and the east and west or in the north, a pold­er sys­tem planned by the Dutch was set up. While the south­ern dry pold­er at Lunow and Stolpe is pro­tect­ed from flood­ing all year round by dikes, the wet pold­er to the north in the east­ern sum­mer dike, in the west­ern win­ter dike and in the dikes to the Schwedter Quer­fahrt has numer­ous inlet and out­let struc­tures that are devel­oped as sluices and sluices . On the Ger­man side, the wet pold­ers (5,400 ha) are flood­ed in win­ter via inlet struc­tures in the sum­mer dike from the north, start­ing between Novem­ber 15 and Decem­ber 15 each year. In the peri­od from March 15 to April 15, the Deich­tore will be closed again, the water flows accord­ing to the gra­di­ent into the Hohen­saat­en-Friedrich­sthaler Wasser­straße, the Schwedter Quer­fahrt and the West­oder, or it is pumped out with the help of the pump­ing sta­tions around the To be able to use pold­ers for agri­cul­ture at an ear­ly stage. Sum­mer floods, which also lead to flood­ing, occur only rarely, usu­al­ly once a decade. The sum­mer dike west of the Stro­mod­er is designed as an over­flow stretch over a length of 800 m below Crieort. It is flood­ed dur­ing high water if the capac­i­ty of the inlet struc­tures is insufficient.

The exten­sive flood­plains in the low­er Oder val­ley have not only proven them­selves as area fil­ters, but also as effec­tive flood pro­tec­tion, not least dur­ing the flood of the cen­tu­ry in the sum­mer of 1997. In July there were two heavy rains in Moravia and Upper Sile­sia with­in 10 days. The first time there was 8–10 bil­lion m³ of rain, the sec­ond time 4–5 bil­lion m³ of rain came down. As a result, the Oder had to trans­port six times the amount of water instead of the usu­al 400 m³/sec. The water lev­el at Hohen­saat­en reached a high of 7.29 m on July 31. In con­trast to the upper reach­es of the Oder in Moravia and Sile­sia, where there are large­ly no flood­plains, there was no sig­nif­i­cant dam­age in the low­er Oder val­ley. The high water peak was absorbed by the exten­sive flood­plain land­scape of the low­er Oder val­ley, the Oder­bruch and down­stream Stet­tin (Szczecin) pro­tect­ed from flooding.

In the final report of the Bran­den­burg state gov­ern­ment of March 31, 1998, the flood dam­age was esti­mat­ed at 648 mil­lion DM. Accord­ing to the Fed­er­al Insti­tute for Hydrol­o­gy in Koblenz, such so-called floods of the cen­tu­ry could repeat them­selves more fre­quent­ly in the future. In the con­text of glob­al warm­ing, the glob­al tem­per­a­ture will rise by around two degrees by 2030, which means that the amount of rain in Ger­many will increase by 100 l / m² per year. The hydraulic engi­neer­ing sys­tems and the pold­er sys­tem require a high lev­el of per­son­nel and finan­cial expen­di­ture for their main­te­nance. The respon­si­ble Bran­den­burg Min­istry of the Envi­ron­ment assumes at least 800,000 DM annu­al main­te­nance and oper­at­ing costs.

The pold­er sys­tem was cre­at­ed at a time when every square meter of arable land was need­ed for agri­cul­ture. Only a small part of the hydraulic engi­neer­ing sys­tems is required to secure the inter­na­tion­al water­way between Berlin and Szczecin and for flood pro­tec­tion, which can already be seen from the fact that the com­pli­cat­ed pold­er man­age­ment in the Gartzer and Schillers­dor­fer pold­er has been dis­con­tin­ued since 1945. For exam­ple, the win­ter dike east of the Hohen­saat­en-Friedrich­sthaler water­way remains indis­pens­able. Most of the oth­er facil­i­ties, start­ing with the sum­mer dyke that accom­pa­nies the stream or to the west, to the inlet and out­let struc­tures, which require a lot of main­te­nance and care, the pump­ing sta­tions and the weed­ing of the ditch­es, are basi­cal­ly addi­tion­al sub­sidy mea­sures for local agriculture.

On the Ger­man side, the hydraulic engi­neer­ing sys­tems were oper­a­tional dur­ing the GDR era, but had not been fun­da­men­tal­ly repaired and renewed for a long time. After a dis­cus­sion, at least in envi­ron­men­tal cir­cles, as to whether it even made sense to renew the inlet and out­let struc­tures after the estab­lish­ment of an allu­vial mead­ow nation­al park, grad­u­al­ly all the inlet and out­let struc­tures were com­plete­ly new and since mon­ey does not play a role in Ger­many built in a mod­ern way, even if they may no longer be used in the future. After all, this can be used to pro­tect the pold­ers from flood­ing in the event of unex­pect­ed spring or sum­mer floods. But actu­al­ly this mil­lion dol­lar invest­ment has been spent quite pointlessly.

After the sum­mer flood of 1997 at the lat­est, it was decid­ed to raise and widen all win­ter and sum­mer dykes, although they were not endan­gered dur­ing this spec­tac­u­lar flood event in the nation­al park area. For the win­ter dike east of the Hohen­saat­en-Friedrich­sthaler Wasser­straße, this may make sense for the pop­u­la­tion west of the Hohen­saat­en-Friedrich­sthaler Wasser­straße for flood pro­tec­tion rea­sons, but it is rather point­less when it comes to upgrad­ing and main­tain­ing the sum­mer dyke. They are even more of a hin­drance for a real flood­plain nation­al park. If the inlet and out­let struc­tures remain open all year round, their effect, which dis­rupts the nat­ur­al flood­plain process, is some­what reduced.

As a result, all hydraulic engi­neer­ing sys­tems in the low­er Oder val­ley have been brought up to date in the last 25 years since reunification.

On the Pol­ish side, pold­er man­age­ment ceased after the end of the war. Even with­out the pold­er areas, Poland had suf­fi­cient arable land. Most of the sum­mer dikes in the Zwis­chen­oder­land are still intact, but the inlet and out­let struc­tures and the locks are no longer func­tion­al. They are open to nat­ur­al flood­ing all year round.

The respon­si­bil­i­ties in the area of water man­age­ment in the low­er Oder val­ley are com­pli­cat­ed. In addi­tion to the Fed­er­al Water­ways and Ship­ping Office in Eber­swalde, the State Envi­ron­ment Office, Depart­ment of Water Pro­tec­tion and Water Man­age­ment, the Low­er Water Author­i­ty of the two affect­ed dis­tricts of Uck­er­mark and Barn­im and the “Welse” water and soil asso­ci­a­tion are responsible.